Method for manufacturing a oscillating tip surgical saw blade

The manufacturing method of the first oscillating tip surgical saw bladeTechnical field

[oooiL This invention relates to a method of manufacturing a surgical saw blade with a stationary saw blade bar and a head pivoting relative to the saw blade bar.

Background technique

[0002] The sagittal saw blade is a surgical saw with a head that pivots about an axis perpendicular to the saw blade. The U.S. Patent Publication No. US2007/0119055 Al filed on August 16, 2006 is named "SURGICAL SAGITTAL SAW WITH INDEXING HEAD AND TOOLLESS BLADE COUPLING ASSEMBLY FOR ACTUATING AN OSCILLATING TIP SAW BLADE AND OSCILLATING TIP SAW BLADE WITH SELF CLEANING The US patent application of "HEAD" is hereby incorporated by reference, and discloses a surgical saw blade assembly including a stationary saw blade bar and a saw blade head. The saw blade bar is an elongated component that is releasably mounted to the handpiece, which is used to drive the component. The saw blade head is pivotally mounted to a saw blade bar having teeth extending forward from the saw blade bar. One or more drive links extend from the saw blade head to the teeth. The drive assembly in the machine head makes the drive link reciprocate back and forth. The alternate reciprocating movement of the drive link causes the saw blade head to pivot back and forth. The saw blade head pivots so that these teeth cut the tissue that the saw blade head presses. Generally, this type of saw blade is an oscillating tip saw blade.

[0003] The advantage of an oscillating tip saw blade is that the only pivoting part of the saw blade is the blade head at the distal end. Compared to a traditional sagittal saw blade that pivots from a point mounted to a complementary handpiece, the saw blade assembly vibrates less in the surgeon's hand holding the handpiece when driven. Likewise, conventional practice is to use a cutting guide to correctly position the sagittal saw blade relative to the tissue to be cut by the saw blade. When driving a conventional saw blade, the oscillating movement of the saw blade imposes wear on the surface of the cutting guide, which defines the slit in which the saw blade sits. The blade bar of the oscillating tip saw blade only moves minimally in this slit. Thus, by using an oscillating tip saw blade, the material forming the cutting guide becomes very little, if any, worn. This reduces the degree to which the surgeon must flush the cutting guide material worn away from the surgical site. Further, the use of an oscillating tip saw blade reduces the degree to which the material forming the guide becomes worn so that the guide itself becomes useless.

[0004] An important part of the above saw blade assembly is the pivoting protrusion. The pivot protrusion is inside the saw blade

200780039072.5 The cylindrical stationary part of No. 200780039072.5, the saw blade head presses and pivots around the saw blade bar. The outer surface of the saw blade protrusion (the surface on which the saw blade head rests) must be as smooth as possible. This is because the rough spots on the surface will cause wear around these spots and the complementary surface of the saw blade head against these surfaces. This wear can cause the failure of one or both of these components. Even if the wear does not cause structural failure, it will also cause considerable friction-induced heating.

[0005] The saw blade bar can be formed by machining the workpiece. During processing, the material forming the workpiece is selectively removed to form a saw blade bar with the desired geometric features including pivoting protrusions. Using this process to form saw blade bars is too expensive to provide an oscillating tip saw blade economically.

[0006] Further, the saw blade bar of the oscillating tip saw blade is usually formed by opposed upper and lower plates. The saw blade head and drive rod are sandwiched between these plates. Once these parts are assembled together, the opposing plates are fixed together to complete the assembly of the oscillating tip saw blade. Care must be taken during this process to ensure that the saw blade rod is processed as straight as possible quickly. If the saw blade bar has any curvature, the saw blade can be bent and sliced when the tissue to be cut is pressed. Such bending of the saw blade can in turn cause the saw blade to cut the tissue along a path that deviates from the path to be cut. This bend can potentially be so large that it negatively affects the ability of the saw blade to travel in the inserted slit guide.

Summary of the invention

[0007] The present invention relates to a novel and effective method of manufacturing an oscillating tip saw blade. In a process of the present invention, the saw blade bar pivoting protrusion is gradually formed in a plate, forming a pivoting protrusion. Then, the board forming the saw blade bar is welded in a selected pattern to sufficiently eliminate the deformation of the board due to the welding process.

[0008] In a process of the present invention, the first step of forming the pivoting protrusion includes punching a relatively deep bullet-shaped node in the plate where the pivoting protrusion is to be formed. Then, in a series of additional sequential stamping steps, the node is widened to provide the node with a cylindrical outer contour. In the subsequent stamping process, the node head is gradually flattened to produce the final desired pivot protrusion.

[0009] The above process produces a pivoting protrusion with a cylindrical geometry, and does not excessively damage the surface finish of the rod material forming the geometry.

[0010] Once the saw blade head and drive rod are sandwiched between the plates forming the saw blade bar, the plates are welded together. More specifically, the plates are welded together using a laser welding process. In this process, the gusset plate in the first plate against the second plate is penetrate-welded to the second plate. Then the outer periphery of the board is welded together. Each welding process includes many separate welding steps. In each welding step, parts of the board are spot welded closely spaced. The parts are separated from each other. Thus, between a part of adjacent boards

200780039072.5 After the completion of the first welding, the next welding part is separated from the initial part.

[ooiiL The welding process described above minimizes the extent to which any of the individual rod-forming plates are heated. This reduces the deformation of the material forming the board. This reduction in deformation also minimizes the degree to which the saw blade bar becomes bent during the forming process.

Description of the drawings

[0012] The above and further features and advantages of the present invention can be understood from the following detailed description with reference to the accompanying drawings:

[0013] Figure 1 is a perspective view of the oscillating tip saw blade of the present invention installed on the handpiece.

[0014] Figure 2 is an exploded view of the vibrating tip saw blade.

C0015L Figure 3 is an enlarged cross-sectional view of the problem area, which occurs if the pivot protrusion of the saw blade bar does not have a cylindrical profile.

[0016].

[0017]. Figure.

[0018]. Figure.

[0019]. Figure.

[0020]. Figure.

[0021]. Figure.

[0022], FIG. 4 is an illustration of a press used to form the saw blade bar according to the present invention.

Figure 5 is a partial cross-sectional side view of how the first punch begins to pivot the protrusion forming process. Side view 6 is a partial cross-sectional view of how the second punch continues to pivot the protrusion forming process. Side view 7 is how the third punch continues to pivot the protrusion. Partial cross-sectional view of the forming process Side view 8 is a partial cross-sectional view of how the fourth punch continues to pivot the protrusion forming process Side view 9 is a partial cross-sectional view of how the fifth punch continues to pivot the protrusion forming process Side view 10 is the sixth A partial cross-sectional side view of how the punch continues to pivot the protrusion formation process.

[0023] Figure 11 is a partial cross-sectional side view of how the seventh punch is completed.

[0024] FIG. 12 illustrates the sequence of performing penetration welding on the upper and lower plates forming the saw blade bar to form the saw blade bar.

[0025] FIG. 13 illustrates the sequence of forming welds to weld the opposite edge surfaces of the upper and lower plates together.

[0026L FIG. 13A is a diagram illustrating the formation of the gap between the upper and lower plates of the saw blade bar before welding.

200780039072.5 Sectional view, the gap is enlarged for illustration.

[0027L FIG. 14A is a perspective view of an optional pivot in the present invention.

[0028] FIG. 14B is a cross-sectional view illustrating how the pivot shaft of FIG. 14A is mounted to the saw blade bar so that the central head of the shaft serves as a saw blade pivot protrusion.

[0029] FIG. 15A is a perspective view of an optional pivot in the present invention.

[0030] FIG. 15B is a cross-sectional view illustrating how the pivot shaft of FIG. 15A is mounted to the saw blade bar so that the central head of the shaft serves as a saw blade pivot protrusion.

[0031] Figure 16A is a top plan view of the optional saw blade assembly of the present invention.

[0032] FIG. 16B is a side view of the optional saw blade assembly shown in FIG. 16A.

[0033L FIG. 17 is a plan view of the saw blade head integrated with the saw blade assembly in FIG. 16A; and

[0034L FIG. 18 is a plan view of the distal ends of the two drive rods of the present invention and the connecting feet of another saw blade assembly.

[0035L It should be appreciated that the above-mentioned drawings illustrating the mechanical components of the present invention should be understood as generally showing the respective features of the components and the relative proportions between them. A diagram showing its features enlarged for ease of illustration is shown.

Detailed ways

[0036] Figures 1 and 2 illustrate the saw blade assembly 40 mounted on the handpiece 42 according to the present invention. The saw blade assembly 40 includes a saw blade bar 44 that is removably mounted to the distal end of the handpiece 42. ("Far" refers to the point of operation away from the surgeon and toward the component application, and "near" refers to the point of operation toward the surgeon and away from the point of operation). The saw blade head 46 is placed in the saw blade bar 44 and pivotally mounted to it. The saw blade head 46 has a crown 48 located in front of the saw blade rod 44. The crown 48 is formed with cutting teeth 49. The drive rod 50 placed in the saw blade bar 44 extends rearwardly from the saw blade head 46 toward the proximal end. The drive rod 50 is releasably connected to an oscillating drive mechanism inside the handpiece (the drive mechanism is not shown and is not part of the invention). As a result of the driving of the driving mechanism, the driving rod 50 reciprocates back and forth. The reciprocating movement of the drive rod 50 causes the saw blade head 46 to pivot.

[0037] The saw blade bar 44 is formed by the lower and upper plates 54 and 56 respectively. The lower plate 54 has a base 58 at the proximal end, which is generally trapezoidal, in which the opposite lateral side edges are symmetrical and taper inwardly toward the proximal edge of the plate 54. The lower plate base 58 is further formed with two D-shaped openings 62. The longitudinal axis of the opening 62 is symmetrically separated from and parallel to the longitudinal axis of the lower plate 54.

[0038] The lower plate 54 is formed with an intermediate portion 64 in front of the base portion 58. The side edges of the middle portion 64 follow

200780039072.5 It extends forward toward the distal end and tapers inward. The middle part of the plate 64 is transformed into a distal part 66 of the saw blade with fixed width. The lower plate 54 is further formed to define a keyhole-shaped opening 68 that extends from the middle portion 62 to the distal portion 66. The size of the opening 68 is designed to receive the connecting pin 70 as a part of the handpiece 42. The connecting pin 70 is a part of the handpiece part that releasably holds the saw blade bar 44 to the handpiece.

[0039] The front of the distal portion 66 of the rod lower plate is formed with a circular, upwardly extending protrusion 74. On each side of the protrusion 74, the lower plate 54 defines a D-shaped opening 76. Each opening 76 is longitudinally aligned with a single one of the openings 62. The lower plate 54 is also formed with two pairs of L-shaped patch wings 78. Each patch 78 is located directly inward of the longitudinal side adjacent to the plate 54. Each patch 78 extends upward toward the upper plate 56. The pads 78 are arranged in pairs so that each of each pair is completely opposite to the second of the pair. The first pair of patches 78 are located along a line away from the opening 68. The second pair of patches 78 are positioned along the line between the first set of patches 78 and the opening 76.

[0040] Before the opening 76, the lower plate 54 is formed with two additional openings, a discharge port 82. More specifically, the discharge port 82 is opened from the surface portion of the lower plate which faces the blade head base 124. Each discharge port 82 is approximately oval. The lower plate 54 is further formed so that the discharge ports 82 are centered on a common non-linear longitudinal axis. More particularly the axis is curved. In the center of the radius of curvature of the axis, the part of the saw blade head 46 arranged below the port oscillates. The discharge port 82 is located symmetrically around the longitudinal axis of the lower plate 54.

[0041] Two rows of oval openings 84 are also formed in the lower plate 54. Each row of openings 84 is located on the side edge of the plate 54 directly inward. Each row of openings begins with an opening directly adjacent to the distal edge of the lower plate 54 and extends from the most distal opening 84 back toward the proximal end. Each row of openings 84 extends a short distance rearwardly toward the proximal end from the adjacent discharge port 82.

[0042] The upper plate 56 is formed into a peripheral contour that is substantially the same as the lower plate 54; the description of the contour is not repeated. The upper plate 56 is further formed with a lip 88 extending downward from the edge of the plate. In general, the dimensions of the plates 54 and 56 are designed so that when the upper plate 56 is placed on the lower plate 54, the upper plate lip 88 extends around the adjacent edge of the lower plate 54. The upper plate 56 is formed so that a lip 88 extends around the proximal end of the lower plate 54 and the opposite side edge of the lower plate 54 longitudinally extending. Thus, when assembled, the saw blade bar 44 has a distal opening (the opening is not shown) between the lower plate 54 and the upper plate 56.

[0043] The upper plate 56 is further formed with two D-shaped openings 90. Each opening 90 is the same in shape as each lower plate opening 62 and can be directly aligned with it. At the rear of the proximal end of the opening 90, the upper plate 56 is further formed with a gusset 92 extending downward. Directly in front of the proximal end of the plate, the gusset 92 extends laterally through the upper plate 56. Two downwardly extending small gussets 94 are located on the gussets

200780039072. 5th

Either side of 92.

[0044] The upper plate 56 is formed with two gusset plates 96 and a single gusset plate 98 in front of the opening 90. The gusset 96 is positioned symmetrically around the longitudinal axis of the upper plate 56. The gusset 96 is located on the lateral sheet portion of the upper plate 56 that has the largest width along the plate. Each gusset 96 is located directly inside the outer peripheral portion of the upper plate 56 which transforms into a lip 88. The gusset 96 is oval.

[0045] The upper plate 56 is formed so that the gusset 98 is centered on the longitudinal axis of the plate and extends along it. The gusset 98 extends from a position slightly closer to the proximal end of the gusset 96 to a proximal end that roughly corresponds to the opening 104 discussed below. The upper plate 56 is formed so that the gusset 98 adjacent to the gusset 96 is relatively wider. (The "wide" and "narrow" of the gusset 98 refer to the width of the gusset along its transverse axis). At the front of the proximal end of the gusset 98, a keyhole-shaped opening 102 is formed in the gusset 98. The opening 102 has the same size as the lower plate opening 68 and can be aligned with the opening 68. Far forward from the opening 102, the upper plate 56 is formed so that the gusset 98 has a relatively narrow constant width.

[0046] A pair of additional D-shaped openings 104 extend through the distal end of the upper plate 56. Each opening 104 has the same shape and is aligned with the complementary lower plate opening 76. In front of the opening 104, the upper plate 56 is further formed with a triangular gusset 106. The gusset 106 is centered on the longitudinal centerline of the top plate. The gusset 106 can further extend from the inner surface of the top plate in the area of the surface opposed by the blade head base 124.

[0047] The upper plate 56 is further formed with two rows of oval openings 108. Each row of openings 108 is located adjacent to the side edge of the upper plate. Each row of openings 108, like the lower plate opening 84, extends from the distal end of the plate back toward the proximal end. The lower plate opening 84 and the upper plate opening 108 may or may not overlap each other.

[0048] The drive rod 50 is respectively arranged between the lower and upper plates 54 and 56 of the saw blade bar. Each driving rod 50 is in the shape of an elongated metal flat strip. The drive rod 50 is formed so as to have a circular foot 114 at the proximal end of each rod. Each leg 114 is formed to have a centrally located through hole 116. The size of the through hole 116 is designed so that the related drive rod foot 114 can be fitted to the drive pin integral with the handpiece 42.

[0049] It should be realized that the drive rods 50 are formed so that their feet 114 are thicker than the elongated central body. In some variations of the present invention, the basic thickness of the drive rod 50 is approximately 0.38 mm (0.015 inches); the reinforcement ring surrounding the hole 116 allows the part of the rod to have a thickness of approximately 1.14ππη (0.045 inches) . In some variations of the present invention, the drive rod 50 is shaped by selective grinding of the workpiece forming the drive rod.

[0050] The saw blade head 46 has a base 124 that is a part of the saw blade head from which the crown 48 extends. The saw blade head is located in the gap between the upper and lower plates 54 and 56 respectively. In a variant of the present invention,

200780039072.5 The base of the saw blade head has a thickness of approximately 0.025 mm (0.001 inch), which is smaller than the width of the gap between the opposite faces of the upper and lower plates. The saw blade head base 124 is formed so as to have a proximal end 126 and an adjacent distal end 128. Although not marked, it can be seen that extending forward from the proximal end of the proximal portion 126, the side edge of the saw blade base is tapered inward. The blade base distal portion 128 has a proximal end extending outward from the narrow end of the adjacent proximal portion 126.

[0051] The saw blade head base 124 is further formed so that the adjacent proximal portion 126 has a pair of opposed bases 132 at the proximal end of the saw blade head base 124. Each base 132 is shaped like an arc. A completely opposite through hole 134 is further formed in the saw blade head base 124 and is located directly in front of the proximal end. Each through hole 134 is centered on the axis, and adjacent legs 132 are centered around the axis. The distal end of the saw blade base 124 is further formed to define a concave semicircular notch 138. The notch 138 is centered along the longitudinal axis of the saw blade head 46. More specifically, the size of the notch 138 is designed so that when the saw blade 40 is assembled, the lower plate protrusion 74 is seated in the notch 138 and the saw blade head 46 can pivot about the protrusion. [0052] The distal end portion 128 of the saw blade head base has two side edges (not marked), extending distally along the saw blade head and tapering inward. The base distal end 128 is further formed to define a transparent window 140. The window 140 is positioned so that when the saw blade 40 is assembled, the upper plate gusset 106 extends through the window.

[0053] The blade crown 48 has a greater thickness than the associated base 124. More specifically, the saw blade head crown 48 is formed so that the cut made by the crown is wide enough to allow the saw blade bar 44 to be inserted into the cut. The crown is often formed so that the cut is at least 0.025 mm (0.001 inch) larger than the thickness of the saw blade bar 44. The precise geometry of the saw blade crown 48 is a function of the particular cut geometry and is not relevant to the present invention.

[0054] The finger 142 and the pin 144 pivotally hold the saw blade head 46 to the drive rod 50. A pair of fingers 142 extend forward from the distal surface of each drive rod 50. The finger 142 is formed integrally with the driving rod 50. The surface of each drive rod 50 is ground to form an elongated body with a small thickness and a relatively wide distal end. A cutting process such as a wire electrical discharge machining process is used to form a cut for separating the fingers, and the saw blade head base 124 is slidably assembled in the cut. In the surface grinding process, each driving rod 50 is further formed so as to define a relatively thick leg 114.

[0055] Each finger is formed with a through hole 146. When the saw blade 40 is assembled, the pin 144 extends through the finger hole 146 and the saw blade base hole 134 to pivotally hold the drive rod 50 to the saw blade head 46. In some variations of the present invention, the pin 144 is formed of stainless steel, such as stainless steel material type EN100-3

1. 4034 or 400 series stainless steel.

[0056] The pin 144 is often fastened in place using a laser welding process. This is a two-step process. In the first step of this process, the outer circular edge at one end of pin 144 is laser welded to the drive rod finger

200780039072.5 No.

Adjacent to the edge of 142, the finger defines the hole 144 in which the pin sits. Then, in the second step of the process, the opposite end of the pin is laser welded to the adjacent edge surface of the opposing finger 142.

[0057]-Once the saw blade head and drive rod accessories are manufactured, the accessories are placed against the inner surface of the upper plate 56. The lower plate 54 fits within the upper plate lip 88. As a result of this arrangement, relatively thick driving rod feet are placed in the lower and upper plate openings 62 and 90, respectively. The fingers 142 and the pins 144 are placed in the lower and upper plate openings 76 and 104, respectively.

[0058] When the saw blade 40 is assembled to the machine head 42, the drive pin and the drive rod 50 integrated with the machine head cooperate to pull the saw blade head base 124 against the saw blade rod protrusion 74. In the process of driving the saw blade 40, the concave surface of the saw blade head defining the notch 138 thus pivots back and forth against the protrusion 74. FIG. 3 is an enlarged view of what happens if the circumferential surface of the protrusion 74 against which the saw blade head base 124 abuts is not substantially cylindrical. Specifically, if due to an inaccurate manufacturing method, the protruding surface is away from the notch defining surface of the saw blade head base 124 and becomes thinner toward the proximal end. In FIG. 3, this narrowing referred to by the identification number 148 is enlarged for illustration purposes. Specifically, in this case, the force exerted by the saw blade head base 124 on the protrusion 74 is distributed in a relatively narrow area, which is led by the identification number 149. This means that the area is subject to considerable mechanical stress and heat caused by friction. As a result, these two concentrated forms of energy can potentially lead to the failure of the protrusion-forming material.

[0059] Now referring to FIG. 4, a method of manufacturing the lower plate 54 to produce a relatively cylindrical pivoting protrusion will be described. Specifically, in a series of stamping steps, the pivoting protrusion 74 is formed in the lower plate. In Fig. 4, a progressive metal press 150 that completes these steps is illustrated. The press 150 has a stationary lower die plate 152. The lower template 152 has an exposed top surface 154. A metal belt 158 extends on the template surface 154, and the metal belt continuously forms a number of lower plates 54. The upper stamping plate 160 is located on the top surface 154 of the lower template. Many punches 162-174 are suspended from the upper punching plate 160 and facing the lower die plate 152. Below each punch 162-174, the lower mold plate 152 is formed with bore holes 178-190, respectively. Every place with a punching-drilling pair can be considered as a separate punching station on the press 150.

[0060] The metal press 150 also includes a pressing plate 194. The pressing plate 194 extends under the upper punching plate 160 and is suspended from the upper punching plate by a set of springs 196. The pressing plate 194 is formed with a plurality of through holes 197. Each punch 162-174 is located in a single through hole 197 of the pressure plate.

[0061] The drive mechanism is not shown but can be understood as part of the metal press 150, which forces the upper punching plate 160, punches 162-174 and pressing plate 194 to press against the metal belt 158 under the template below. In some variations of the present invention, the drive mechanism can force the upper stamping plate 160 to press against the template with a force between 227 metric tons (250 metric tons) and 454 metric tons (500 metric tons). In some of the present invention

200780039072.5 In the first modification, the driving mechanism can force the upper punching plate 160 to press against the template with a minimum force of 90 metric tons.

[0062] The transfer mechanism installed to the metal press 150 is also not shown. The transfer mechanism moves the metal belt 158 between each of the seven stamping stations in a step-by-step mode. Thus, in each operation of the press 150, the stamping steps are completed on seven different parts of the metal belt. After performing the seventh step for each belt portion, it can be considered that the pivoting protrusion 74 is completely formed. After this seventh step, each lower plate forming portion of the metal belt 158 can withstand additional pressure operations. These punching operations have nothing to do with the formation of the protrusion 74.

[0063] In some preferred variations of the present invention, a metal band 158 formed of 420 stainless steel or an equivalent metal forms the lower and upper plates 54 and 56. Such a metal is available from Sandvik 7C27Mo2 strip steel of Sandvik AB, Sandviken, Sweden. It can be seen that the material has a chemical composition (by weight): 0.38% carbon, 0.40% silicon, 0.55% manganese, up to 0.025% phosphorus, up to 0.010% sulfur, 13.5% The saw, the remainder is iron. The thickness of the metal belt 158 is 0.38 mm (0.015 inch) or less.

[0064] Each time the metal press is driven, the pressing plate 194 is pressed against the metal belt 158. The pressing plate 194 compresses the metal belt 158 to hold the metal belt to the top surface 154 of the template. When the upper punching plate 160 continues to move downward, each punch 162-174 extends through the relevant plate through hole 197. These punches then press the lower part of the metal belt into which the metal belt is plunged and accessible at the punching station. Each punch 162-174 then forces the underlying metal strip into its associated die bore 178-190. This continuous stamping of the metal strip results in the pivoting protrusion 74 being formed with the desired cylindrical geometry.

[0065] FIG. 5 shows how the punch 162 begins to form the pivoting protrusion 74 in the first stamping step. The punch 162 has a wide diameter base (not shown), as do the remaining punches 164-174. The base is shaped to facilitate tight sliding of the punch in the associated plate through hole 197. An elongated rod 204 of narrow diameter extends downward from the base. The head, which is narrower than the rod, extends under the rod. The head of the punch 162 is shaped to define a cylindrical foot 208. The pedestal 208 has a diameter smaller than the diameter of the associated rod 204. Below the pedestal 208, the punch 162 has a tip 210. The tip 210 is the part of the punch 162 that strikes the metal band 158 below. The tip 210 has a bullet-shaped profile. Thus, the tip 210 has a central surface 212 with a first radius of curvature of a narrow diameter. The tip 210 also has a peripheral surface 214 extending between the central surface 212 and the outer periphery of the head pedestal 208. The peripheral surface 214 has a radius of curvature greater than that of the central surface 212. Although the radii of curvature of the central surface 212 and the peripheral surface 214 are different, both curved surfaces are centered on the longitudinal center line of the punch 162. The center of curvature of the central surface 212 is closer to the end of the punch 162 than the center of curvature of the peripheral surface 214.

200780039072.5 No.

[0066] In this punching step, the head of the punch 162 drives the previously flat portion of the metal belt into the template drill hole 178 below. Thus, the result of this step is that the metal band now has a projection in the shape of a bullet, which is indicated by the identification number 217.

[0067] Between the first and second punching steps, the portion forming the bullet-shaped protrusion of the metal belt 158 is transferred to the punching station where the second punch 164 is located. It should be understood that a similar transfer occurs after each stamping step. These additional transfer steps are not discussed further.

[0068] The second to seventh punches 164-174 reshape the protrusion 74 so as to have a designed cylindrical shape. The second punch 164 best shown in FIG. 6 has a rod 217 from which a cylindrical stud 218 extends and has a diameter smaller than that of the rod 217. The pedestal is shaped to have an extended round tip 220. The diameter of the foot 218 of the second punch 164 is wider than the diameter of the foot 208 of the first punch 162. The tip 220 is shaped to have a round central surface 222 with a first radius of curvature. Between the central surface 222 and the pedestal 214 Z, the tip 220 has a peripheral surface 224. The radius of curvature of the peripheral surface 224 is greater than the radius of curvature of the central portion 222. Thus, along any side line passing through the second punch tip 220, the central surface 222 has a radius of curvature centered on a point along the longitudinal axis passing through the punch 164. At the opposite end of the tip 220, the peripheral surface 224 has two radii of curvature located on opposite sides of the longitudinal axis.

[0069] It should also be understood that the total length of the second punch 164 from the free end of the base 162 to the opposite end of the tip central portion 222 is shorter than the comparable length of the first punch 162. The differences in these lengths are exaggerated for illustration purposes in FIG. 4. Therefore, as can be seen in Fig. 6, the result of the second stamping step is that the end of the protrusion is compared with the shape of the first step to form an end with a smaller roundness, and the transition portion directly above the end has a smaller curvature. , The angle is larger.

[0070] FIG. 7 illustrates the shape of the third punch, the punch 166, and the protrusion that deforms due to the punch. In particular, the third punch 166 has a tip 232 having a substantially cylindrical shape. The diameter of the tip 232 is greater than the diameter of the stud 218 of the second punch 164. The tip 232 has a planar outer surface 234. Between the outer surface 234 and the cylindrical side wall, the tip 232 has a curved corner 236. The radius of curvature of the corner 236 is smaller than the radius of curvature of the peripheral surface 224 of the second punch tip.

[0071] The total length of the third punch 166 is less than the total length of the second punch 164. The forming punch 166 and the remaining punches 168-174 so as not to have an intermediate shaft between their base and the metal forming head.

[0072] Therefore, as a result of the third stamping step, the protruding end continues to develop into a flatter shape after being formed. The annular part of the protrusion abutting its top (shown upside down in Figure 7) is also more pressed into a circle

200780039072.5 The shape of the column. Further, as a result of the outward deformation of the material forming the protrusions, the total height of the protrusions begins to decrease relative to their early shape.

[0073] The fourth punch 168 shown in FIG. 8 has a tip 238 that has the same basic geometry as the tip 232 of the third punch 166. The tip 238 has the same outer diameter as the tip 232. The tip 238 also has a flat outer surface 240. Between the outer surface 240 and the cylindrical peripheral surface, the tip 238 has a curved corner 242. The corner 242 has a radius of curvature smaller than that of the corner 236 of the third punch 166. The fourth punch 168 has a total length slightly smaller than the total length of the third punch 166.

[0074] The template bore 184 is not fully opened, and the fourth punch presses therein to form a protrusion. The bore 184 is equipped with a plug 248 like the remaining bores 186, 188 and 190. As shown in FIG. 4, the plug 248 is seated on the substrate 250 located under the template 252. The plug 248 actually rests on the spacer 252, showing a single one resting on the base plate. The spacer 252 is selectively removed and replaced to adjust the relative position of the plug head to the top surface 154 of the template. It should be appreciated that gaskets are similarly applied to place plugs in bores 186, 188, and 190.

[0075] The plug 248 is placed in the bore 184 so that when the shaped protrusion is initially located in the bore, the drill tip rests on the exposed surface of the plug. When the upper punching plate 160 is lowered, the pressing plate 194 keeps the partially formed protrusion against the plug 248. Then the fourth punch 168 presses the inner surface of the metal forming the protrusion. Thus, the end of the protrusion is sandwiched between the top of the plug 248 and the tip 238 of the punch. As a result of this action, the degree to which the top of the protrusion takes on a flat shape increases. Likewise, the degree to which the transition between the annular side wall of the protrusion and its top surface assumes a right-angled profile has increased.

[0076L The fifth punch 170 has a tip 252 that is very similar to the fourth punch tip 238. The outer diameters of these tips are the same. The difference between these tips is that the tip 252 has a radius of curvature of the corner 254 that is smaller than the radius of curvature of the corner of the tip 238 (the transition is sharper). The fifth punch 170 is shorter than the fourth punch 168. The plug 256 is seated in the embossed bore 186, in which the punch 170 is inserted. The plug 256 is placed in the bore 186 so that the tip of the plug and the end of the bore are closer to the top surface of the template than the tip of the plug 248.

[0077] Therefore, in the punching step, the punch tip 252 is pressed against the formed protrusion against the plug 256₀This action further flattens the protrusion and increases the degree to which the protrusion has a cylindrical shape.

[0078] The sixth and seventh stamping steps are similar to the fourth and fifth stamping steps. However, the diameter of the tip 280 of the sixth punch 172 is slightly smaller than the diameter of the fifth punch tip 252. The radius of curvature of the corner surface 282 at the tip of the sixth punch is smaller than the curvature of the corner surface 254 of the fourth punch 170

200780039072.5 The radius. The total length of the sixth punch 172 is less than the total length of the fifth punch 170.

[0079] The plug 284 is located in the template bore 188, and the sixth punch 172 extends into the bore. The shim 252 retains the plug in the bore 284 so that the tip of the bore is closer to the top surface 154 of the template than the tip of the plug.

[0080] The seventh stamping step is the final process of forming the pivoting protrusion 74. The seventh punch 174 has a tip 290 with a diameter equal to the diameter of the fifth punch tip 252. The radius of curvature of the corner 292 that the punch tip 290 has is equal to the radius of curvature of the sixth punch corner surface 282. The seventh punch 174 is slightly shorter than the sixth punch 172.

[0081L A plug 294 is formed in the template bore 190, and the seventh punch 174 extends into the bore. The plug 294 is placed in the bore 190 so that the tip of the plug is closer to the top surface of the template 154θ than that of the tip of the plug 284. [0082] As a result of the seventh stamping step, the pivoting protrusion 74 has a direct approach from the metal forming the lower plate 54 The raised outer wall of the ground. The outer circumferential wall of the pivoting protrusion is cylindrical in nature. The top of the protrusion shown upside down in FIG. 11 is essentially flat.

[0083] In this process, the metal forming the protrusions has the smallest surface stress. This reduction in stress indicates that when the saw blade base is pushed against the pivoting protrusion and repeatedly pivoted around the protrusion, the force of these movements does not cause the failure of the metal forming the protrusion. Further, assuming that the pivoting protrusion presents a cylindrical surface to the saw blade base, the force of the saw blade base against the protrusion is dispersed to a relatively wide area. The heat generated by the pivoting action movement is equally dispersed. The diffusion of this mechanical energy and thermal energy into the pivoting protrusion 74 also serves to minimize the possibility of failure of the material forming the protrusion.

[0084] It should be appreciated that in each stamping step, other processes that need to form the lower plate 54 from the metal strip can be performed. These include the overall forming from the belt to the plate, the formation of the openings 62, 68, 76, and 84, and the formation of the patch 78. In a single step or multiple steps (not shown), the separately formed lower plate 54 is cut from the front end of the metal strip.

[0085] Once the board and the other parts forming the saw blade 40 are formed, these parts are assembled together. A series of laser welding steps are then applied to each fix the lower and upper plates 54 and 56 together. Figures 12 and 13 illustrate the sequence in which this welding occurs. In the first step "1" in FIG. 12, penetration welding through the lower plate 54 is applied to weld the hidden surface of the upper plate gusset 106 to the lower plate 54. In this welding, a series of overlapping spot welding is performed. Each weld has a diameter of approximately 0.97 mm (0.038 inches). The individual welds are approximately 0.33 mm (0.013 inches) apart from each other.

[0086] In the next welding step "2" in FIG. 12, a series of overlapping penetration spot welds are used to weld a portion of the gusset 98 in front of the opening 102 to the lower plate. The welding is close to the opening

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102 and start at a position in front of it, and advance toward the distal end of the saw blade bar. In this step, not the entire gusset is welded to the lower plate in this way. In contrast, in step "3", the lower plate 54 is welded to the gusset 98 at the distal end of the gusset. The weld formed by step "3" stops before reaching the distal end of the weld formed by step "2".

[0087] In the spot welding process of step "2" and step "3", these welds and step "1" have the same diameter. But the welding arrangement of step "2" and step "3" is closer, with a separation of about 0.20 nnn (0.008 inch).

[0088] In step "4", penetration welding is applied to form a substantially U-shaped weld between the lower plate 54 and the wide proximal end of the gusset 98.

[0089] In step "5", an annular weld is formed to weld the lower plate 54 to the top periphery of the pivoting protrusion 74. This is again a through welding process. In this process, individual welds having a diameter of approximately 0.84 mm (0.033 inches) are formed. Approximately 40 spot welds are formed on 360 degrees of this circle to form welds.

[00901 Once a weld is formed along the center of the saw blade bar 44, a weld is formed along the junction where the upper saw blade lip 88 abuts the outer edge of the lower plate 54. Step "6" in Figure 13 represents the beginning of these welds. The welding starts at the distal point of the most distal patch 78 on the side of the saw blade bar and extends forward to a point on the side of one of the openings 84 in FIG. 13, point 290. Step "7" forms the same weld on the opposite side of the saw blade bar 44.

[0091] Once step "6" and step "7" are performed, two additional welds are formed along the side of the saw blade bar 44, and the weld of step "6" is formed along the side. In step "8", a weld is formed along the boundary between the upper plate lip and the lower plate between the two patch wings 78. In step "9", a weld is formed along a line extending from the proximal end patch 78 toward the proximal end.

[0092] Then, in step "10", a short weld is formed between the two plates along the tapered outer edge of the lower plate base 58. In step "11", a weld is formed along the base to start a short distance backward from the proximal end of the weld in step "10". In step "11", a weld is formed around the curve between the side and the proximal end of the lower plate base 58. In each of the steps "8", "9", "10", and "11", the welding is completed along a path moving backward to the proximal end of the saw blade bar 44.

[0093] In the series of steps marked "12", "13", "14" and "15" in FIG. 13, a weld is formed on the opposite side of the saw blade bar. The welding in steps "12", 13", "14" and "15" correspond to the welding in steps "8", "9", "10" and "11", respectively.

[0094] In steps "8" to "15", each spot of overlap spot welding has about 0.71mm

200780039072.5 No. (0.028 inch) diameter. The centers of these welds are approximately 0.32mm (0.0125 inches) apart. [0095] In step "16", a weld is formed in front of the weld produced in step "7". In step "16", the weld is formed to extend to the distal ends of the plates 54 and 56. Then a weld is formed on the opposite sides of the plates 54 and 56 in step "17". Therefore, the welding of step "17" extends in front of the welding produced in step "6". The diameters of the spot welds formed in steps "16" and "17" are the same as the diameters of the spot welds formed in steps "8" to "15". However, these welds overlap more closely. The center point between the welding of steps "16" and "17" is approximately 0.061mm (0.0024 inch) apart.

[0096L In order for the welding of steps "6" to "17" to have the desired strength, the outer edge of the lower rod 54 must be closely positioned relative to the abutting inner surface of the lip 88 of the upper rod 56. The gap 87 (Figure 13A) between these surfaces should not exceed 0.025mm (0.001 inch). Ideally, these surfaces should abut.

[0097] It should be appreciated that other methods can be used to assemble the saw blade 40 so that the pivoting protrusion has the desired geometry.

[0098] For example, components separated from the upper and lower plates formed by the saw blade bar may form pivoting protrusions. 14A illustrates a pivot 301 with a disc-shaped head 302. Two cylindrical ears 304 extend outwardly from opposite faces of the head 302. FIG. The ears have a common diameter smaller than the diameter of the head 302. As shown in FIG. 14B, when the saw blade is assembled or this deformation of the present invention, the protruding ears 304 are seated in separate holes 308 and 310 formed in the lower and upper plates 54 and 56, respectively. The ears are welded to the adjacent board. The pin head 302 serves as a cylindrical member about which the saw blade head 46 pivots.

[0099] In an unillustrated variant of the pivot 301, the pivot has a cylindrical head from which a single ear extends. The ear part is seated in one of the through holes of the lower or upper plate 54 or 56. The plane on the other side of the head can be welded to the abutment surface of the other one of the upper and lower plates.

[00100L Optionally, as shown in FIG. 15A, the pivot 312 may have a spindle shape. The pivot 312 has two large-diameter disc-shaped ears 314. A small diameter cylindrical head 316 extends between the ears 314 and connects them. As shown in FIG. 15B, when the saw blade with the pivot 312 is assembled, the head 316 serves as a cylindrical member about which the saw blade head pivots.

[00101] In some variations of the present invention, the pivot axis about which the saw blade head pivots may be a cylindrical pin with a constant diameter (the pin is not shown). The opposite end of the pin is installed in the aligned opening of the plate forming the saw blade bar. [00102] As shown in FIGS. 16A and 16B, in an alternative variant of the saw blade of the present invention, the saw blade bar 44a is formed with a side opening 330.

200780039072.5 No.

[00103] In this variation of the invention, the saw blade has a saw blade head 46a, and the saw blade head has a base 124a formed with a patch. As shown in Figure 17, the patch 332 extends laterally outward from the side edge of the base distal portion 128a. In the illustrated modification of the present invention, the outer side of the patch 332 has a concave profile. It should be realized that this is illustrative and not restrictive. In some variations of the invention, the patch has a triangular profile. That is, each patch has a surface that tapers outward from the distal end of the base, and the patch extends from the distal end. Then at the widest most proximal position, the angle at which the edge of the patch contacts the distal end is equal to or close to a right angle. In still another variation of the present invention, the outer edge of each patch 332 is a straight edge. Although not shown, it should be appreciated that similar patches extend outward from the proximal end of the base.

[00104] The patching wings are placed so that when the saw blade head 46a is pivoted to one side of the saw blade bar 44, the patching wings extend out of the adjacent opening 330. Therefore, the patch wing serves as a plough that pushes out the debris trapped in the saw blade bar. The discharge of debris minimizes the possibility of debris blocking in the saw blade bar and negatively affecting the operation of the saw blade.

[00105] FIG. 17 also illustrates a saw blade crown 48a having a bow shape. The opposite side edges 340 of the crown are thus located on spaced radial lines extending from the common center point. It is further formed that the saw blade head crown 48a has outwardly projecting fingers 342 at the proximal end of the crown. Each finger 342 extends outward from the associated side edge. Each finger is roughly J-shaped and is positioned so that the hooked end of the finger extends in a forward direction, towards the radius along which the distal end of the serration teeth is positioned.

[00106L When the saw blade with the saw blade head crown 48a is driven, the fingers 342 push the debris trapped in the cutout, which is formed by the saw blade teeth, out of the travel path of the crown 48a. The movement of the debris reduces the degree to which the debris reduces cutting efficiency, and the debris is moved backward to be dragged away in the saw blade bar.

[00107] FIG. 18 illustrates an alternative configuration of a part of the saw blade assembly of the present invention. Specifically, FIG. 18 illustrates how the planar drive foot 350 is connected to the proximal end of the saw blade assembly drive rod 50a. In this variation of the invention, overlapping fingers 352 similar to fingers 142 (FIG. 2) extend rearwardly and proximally from each drive rod 50a. The driving leg 350 has opposite, outwardly extending patch wings 354. Each patch 354 is pivotally mounted into a slot defined by a pair of overlapping drive lever fingers 352.

[00108] The foot 350 also has two opposite fins 356, which are nominally positioned along the longitudinal axis of the saw blade assembly. Each patch 356 has an opening 358. The saw blade assembly of the present invention is used for mounting to a handpiece having a drive head with two drive pins nominally aligned with the longitudinal axis of the handpiece. When the drive pins oscillate, they cause the feet 350 to make similar movements. This movement causes the drive rod 50a to reciprocate back and forth to cause the desired pivoting movement of the saw blade head.

[00109] Optionally, the feet 350 are formed with a central hole with a non-circular profile. This variant of the invention

200780039072.5 The saw blade is installed on a machine head with a single drive pin. The drive pin has a cross-sectional geometry that allows the pin to be tightly slidably mounted in complementary holes in the saw blade foot 350. When driving the handpiece, the driving pin oscillates. This movement results in a similar movement of the foot 350. The foot 350 transmits the oscillating motion to the driving rod 50a so that the driving rod reciprocates.

[00110] Therefore, it should be understood that the above-mentioned specific features related to the manufacturing method and saw blade of the present invention. The present invention may vary from what has been described.

[00111] For example, it is not necessary to implement a method of forming a pivoting protrusion by punching and a method of laser welding upper and lower plates formed of rods in all modifications of the present invention. These methods can be implemented separately when appropriate.

[00112] In the method of forming the pivoting protrusion by stamping of the present invention, more or fewer steps may be required to form the pivoting protrusion so that the protrusion has the desired geometry and ensures that the material forming the protrusion has the desired Stress-free surface finish.

[00113] Alternative methods can be used to form the pivoting protrusion. For example, the blank workpiece can be selectively etched to form the pivoting protrusion and the remaining part of the plate, and the remaining part and the pivoting protrusion are integral. The result of this etching is that at least the pivoting protrusion, or other features of the saw blade board, produces the desired shape. Likewise, in some variations of the present invention, the outer wall of the pivoting protrusion may not have a completely circular cross-sectional profile.

[00114] An optional sequence of laser welding for welding the upper and lower plates together according to the present invention can be implemented.

[00115] Further, in some variations of the present invention, a process other than laser welding may be performed to form the desired weld. Therefore, in some variations of the present invention, arc welding, split electron beam or resistance welding may be used together to form the center welding of the gusset and/or the welding of the upper and lower plates 54 and 56 sides, respectively.

[00116] Therefore, the objective of the appended claims is to cover all such changes and modifications within the essential spirit and scope of the present invention.

200780039072.5