Screwdriving apparatus for use in driving screws joined together in a strip

Description: TECHNICAL FIELD [Detailed description of the invention] Scope of invention The present invention relates to screwdrivers that are generally configured to screw in screws that are attached to a strip, and more specifically adapted to be used to screw in a large number of screws of different lengths and different screw head diameters. Regarding possible electric screw turning. Background of the invention Electric screwdrivers are known that are used to screw screws that are collated and attached in parallel to an essential belt or plastic strip at intervals. One such electric screwdriver is described in US Pat. No. 4,146,071 by Mueller et al., Patented on March 27, 1979. The disclosure items of this patent are incorporated in the present application. Such a known electric screwdriver includes a screwdriver shaft that is rotatable and reciprocating, and the shaft is rotated by an electric motor. The screwdriver bit protected at the tip of this shaft engages with the head of each screw that is continuous when the screw moves to the screwed position and is aligned axially directly below the screwdriver shaft. A matching chip is formed. At the screwed position, a cup-shaped screw positioning member is provided to hold the peripheral edge of the screw head. In general, this screw positioning member determines the radial extent of the lumen path through which the shaft and screw move axially when the screw is screwed. The lumen path preferably has a diameter slightly larger than the outer diameter of the screw head. The shaft is reciprocally movable in the luminal path in the axial direction, and engages with the screw to screw the screw into the work material. After each screw is screwed in, the shaft retracts, then the next screw held in the strip is advanced laterally into the lumen and this screw engages the positioning member directly below the shaft. Arrange them in a straight line in the axial direction. The shaft generally has a diameter equal to or slightly smaller than the diameter of the screw head so that each screw does not unfavorably wear against the positioning member as it is screwed in. In known electric screwdrivers, it is impractical to use this screwdriver for screws with different diameter screwheads, as the positioning member is often fixed to the shaft. For example, when a screw whose head diameter is considerably larger than the diameter of the lumen path is inserted, the screw abuts on the positioning member at a position deviating from the axially straight line with the shaft and the screw bit. Similarly, if a screw whose head diameter is significantly smaller than the diameter of the axial lumen path is used, the screw will also come into contact with the screw positioning member at a position deviating from the shaft and the screw bit in the axial direction. .. In either case, the tip does not engage properly with the head of the screw, resulting in faster tip wear or deviation from the correct axial orientation required to screw the screw. In order to configure the electric screwdriver to adapt to screw heads of various sizes, the screw positioning member could be made to move inward and outward in the radial direction with respect to the lumen path. Providing a movable positioning member has the disadvantages of additional manufacturing costs and that the cup-shaped positioning member is fixed and selected to engage the peripheral surface of a screw head of only one diameter. Therefore, a screw whose head is too small or too large cannot be supported by the positioning member. Moreover, when a movable positioning member is used to adapt to a screw with a small diameter of the head, the shaft and / or bit designed to be used for screwing with a screw with a large diameter of the head hits the positioning member. It wears unfavorably. Abstract of the invention To overcome the shortcomings of prior art, the present invention screwed in a screw in which, in the screwed state, each screw is held in an axial alignment with the screwdriver bit by contacting the positioning member. It provides a screwdriver. This positioning member can be removed from the screwdriver and replaces another positioning member formed to abut on a second screw with a different diameter of the screw head and hold the screw in an axial alignment with the bit. Can be done. An object of the present invention is to provide a screwdriver for screwing screws having different head diameters, which is used to optimally arrange and screw various screws having a specific length or a specific screw head diameter. The screwdriver of the present invention can be customized quickly and at a low cost. Another object of the present invention is to provide an improved screwdriver, the screw bit being increased in response to an increase or decrease in the diameter of the screw head to reduce the unfavorable wear that occurs on the positioning member. Can be made smaller. Yet another object of the present invention is to provide an electric screwdriver that can be adapted to screw in screws of different sizes or lengths of screw heads, in which the screws are spaced parallel in the support strip. It is placed and collated. Yet another object of the present invention is a device for driving a fastener that generally includes both a nail and a screw, the apparatus comprising a driver and a removable pair of a respective complementary fastener positioning member and a driver guide member. Each pair is configured to be used to screw in a fastener with a selected diameter that is different from the diameter of the other pair of fasteners. Embodiment of the invention The screwdriver of one embodiment of the present invention comprises a rotatable bit used to engage and rotate the head of the screw being screwed in. The screw positioning member is provided to abut the peripheral surface of the screw to help align the screw in an axial alignment with the bit and maintain it in the proper screwing position. As a result, the positioning member includes a guide path that forms a lumen formed by the side wall. The screw-in bit is rotatably received and reciprocating in the guide path and engages with each screw arranged coaxially with the bit to screw the screw. An access opening sized to allow the screw head to move through the guideway is provided on a portion of the side wall. Once moved into the guideway, the screw is placed coaxially with the bit by engaging a portion of the screw with a portion of the side wall. The positioning member is movable from a screwdriver and can be replaced by another alternative positioning member provided with a different sized lumen formed by the side wall as a guide path. The alternative positioning member is formed to have an access opening formed to engage some of the screws having different diameters of the head and / or to allow screws of different lengths to move in the guideway. The positioning member preferably comprises a guide tube having a lumen forming a cylindrical guide path. This guide path defines the radial length of the axial luminal path into which the screw is screwed. Such an axial lumen path generally includes a space between the work piece and the screw bit, which space is occupied by the screw as it is screwed into the work material. The diameter of the lumen path is preferably slightly larger than the outermost diameter of the screw to be screwed in, so that the screw advancing into the guide path has the outermost radial part of the screw head as part of the side wall. By abutting, they are held in line with the bit in a straight line. The guide tube is removable from the screwdriver and is replaced with another guide tube that defines the radius of the axial lumen with a diameter slightly larger than the diameter of screw heads of different sizes. By replacing the guide tube, an axial lumen path having a diameter complementary to the diameter of the screw head to be screwed in can be advantageously selected. In this method, the screw positioning member can be customized to abutively engage with a screw head of any size selected, ensuring that the screws are properly aligned in the threaded position, and The possibility that the screw will deviate from the correct axial orientation when screwed in can be minimized. The bit is preferably removable with the guide tube and is replaced with another bit sized to make a complementary rotational engagement within the guide path of the alternative guide tube. In this way, the bit can be paired with the guide tube to minimize the unfavorable wear caused by the bit hitting the side wall. More preferably, the screwdriver of the present invention is an electric screwdriver used to screw in a continuously advancing screw that is matched with a strip. The screwdriver comprises a sliding body having a lumen in which the guide tube is removably housed. One end of this guide tube is notched and has a radial spread of at least about 180 °. A screw access opening with an extent) is formed. The outlet opening is installed in the portion of the guide tube that is radially opposite to the portion of the screw access opening. The size of the outlet opening is selected so that as each screw advances, the strip holding the screw can move out of the guide tube substantially unobstructed. The screw-screw bit is preferably detachably attached to the end of an elongated cylindrical mandrel, which forms a motor-driven screwdriver shaft. The shaft comprises at least one cylindrical positioning portion that rotatably engages the side wall of the guide tube, which helps maintain the shaft coaxially oriented with the guide tube in the guide path. Preferably, the side wall, which is part of the guide tube, surrounds and coaxially positions at least one shaft of the positioning member whenever a screw is screwed in. Thus, in one embodiment, the present invention relates to a screwdriver assembly that screws screws matched with strips at intervals parallel to each other, the screwdriver being detachably secured to the body means; body means. Attached guide tube means; elongated driver shaft means with a bit means at the front end and a cylindrical positioning portion; and screw feed means, the guide tube means having a head of first diameter. A substantially cylindrical side wall that is configured to accept a first screw of similar size, has a cylindrical guideway with an inner diameter slightly larger than the first diameter, and faces the guideway around the guideway. The elongated driver shaft means has a cylindrical positioning portion having a diameter approximately equal to the first diameter and is complementary in size to the guide tube means and is relative in the guideway. It is arranged coaxially in the guideway so as to rotate and reciprocate axially with respect to the guideway; the side wall is provided with a rear shaft guide portion and a front screw positioning portion at the rear portion. And at the front, the locating portion of the shaft means is sufficiently enclosed, the shaft means is placed coaxially with the guideway, and the side wall opens radially, with a screw opening having a radial spread of at least about 180 °. The screw feeding means advances the screws matched by the strips parallel to each other in order in the guide path in the radial direction through the screw access opening, in which case the side walls are similarly sized. Engaging with the screw head of the screw head, the screw head is arranged coaxially and axially in the guide path in an axial line with the bit means, and the shaft means is axially arranged over the entire length of the guide path. Can reciprocate to engage the screw, then screw the screw axially from the guideway into the work piece; complementary sized guide tube means and shaft means are removable and It replaces other complementary sized guide tube means and shaft means configured to engage and screw in a similarly sized screw of a second diameter that is different from one diameter in the same way. In another embodiment, the present invention provides an improved electric nail driver, preferably a pneumatic nail driver that encloses a nail. The nail driver includes a body with a lumen to which the guide tube is detachably attached. Complementary and removable blades that enclose nails are capable of axially reciprocating and reciprocating within the guide tube and are guided through the tube to enclose the nails that are placed and guided within the guide tube. Adapt the nail driver to squeeze nails of different head diameters by making the guide tube and its complementary nail squeeze blade replaceable. Different systems can be used to adjust for nails of different lengths. Therefore, in another aspect, the present invention provides the following screwdriver assembly. That is, it is a screwdriver assembly for screwing an elongated fastener having an enlarged head, and the screwdriver is a screwdriver. Body means and Equipped with a guide tube means that is detachably fixed and attached to the main body means; The guide tube means is configured to accept a similarly sized first fastener with a head having a first diameter, and a cylindrical guide with an inner diameter slightly larger than the first diameter and the guide. With a cylindrical side wall around the In addition, the screw turning An elongated screw sized complementary to the guide tube means by having a fastener engaging means at the front end and having a cylindrical positioning portion whose diameter of the cylindrical positioning portion is approximately equal to the first diameter. Equipped with a turning shaft means; The first means is coaxially arranged in the guideway and slides reciprocally in the axial direction with respect to the guideway; The side wall has a rear shaft guide portion and a front fastener positioning portion; At the rear, the sidewalls sufficiently surround the positioning portion of the shaft means and the shaft means is coaxially arranged in the guideway; In addition, the screw turning The fasteners are advanced in order in the guideway, the side wall is engaged with the head of the fastener of the same size, and the head of the fastener is coaxially arranged in the guideway in the axial direction. Equipped with a fastener supply means that aligns with the joint means in the axial direction, The shaft means can reciprocate axially over the entire length of the guideway, engages the fasteners, and screws the fasteners axially from the guideway into the work piece; Complementary sized guide tube means and shaft means are removable so that they engage in a similar size fastener with a second diameter different from the first diameter in the same way and screw in the fastener. Replaced with other complementary sized guide tube means and shaft means configured; It is a screw turning assembly. In other embodiments, the present invention It is a device that automatically screwes in fasteners such as screws that are connected to a strip with electric power; Housing means; Drive means attached to housing means; Screw-in shaft means that is operatively connected to the drive means and rotates to form a vertical axis; Main body means connected to a housing that displaces between the extension position and the retracted position parallel to the axis of the screwed shaft means; A spring means that urges the main body means at an extension position forward with respect to the housing means parallel to the axis; and The main body means is provided with a guide channel means used for the strip of the fastener extending through the main body means; the main body means is coaxially provided with a guide tube means around the axis of the screwed shaft means, and the guide tube means is similar. When a screw of a size advances into the tube means by the guide channel means, the screw is received, and the screw is arranged axially in line with the screw shaft means, and the screw is screwed from the guide tube means by the screw shaft means. Engage when squeezing; It provides an improved device in which the guide tube means is removable from the body means and can be replaced with other guide tube means configured to accept screws of the same or different size. A brief description of the screen Another aspect and advantage of the present invention will become apparent from the following description made with reference to the accompanying drawings below. FIG. 1 is a schematic cross-sectional view of a US Pat. No. 4,146,071 electric screwdriver modified by incorporating a guide tube according to a first preferred embodiment of the present invention, showing a sliding body in a retracted position. .. FIG. 2 shows a perspective view of the guide tube of FIG. FIG. 3 shows a partially cross-sectional disassembled side view of the sliding body, the guide tube, and the screw turning shaft of FIG. FIG. 4 shows a partially cutout view of a simple deformation of the sliding body of FIG. 3 having a guide tube and a screw-in shaft in an assembled form. FIG. 5 shows an enlarged sectional view taken along line IV-IV'of the sliding body, guide tube and shaft of FIG. FIG. 6 shows an enlarged cross-sectional view of the sliding body of FIG. 5 in which the inserted guide tube and the screw turning shaft are replaced. FIG. 7 is a front painting view of the electric screwdriver of FIG. 1 in which the sliding main body is in the extended position. FIG. 8 is a cross-sectional plan view of the electric screwdriver of FIG. 7 along the VII-VII'line, and the cross-sectional line I-I'in the drawing shows the cross-sectional line of FIG. FIG. 9 is a front view of a disassembled partial painting of the sliding body of the electric screwdriver shown in FIGS. 1, 7 and 8, which is modified by incorporating the guide tube of the second embodiment of the present invention. FIG. 10 shows a strip-shaped body in which a guide tube is inserted into the sliding body and screws are arranged. 9 is a partial cross-sectional plan view of the second embodiment of FIG. FIG. 11 is the same view as the one shown in FIG. 10, but shows a guide tube with a different size of inner diameter that accepts similarly sized screws on the strip. Detailed explanation of drawings ... Examples Figures 1, 7 and 8 showing some of the types of motorized screwdrivers 10 disclosed in US Pat. No. 4,146,071 are first described. The screwdriver 10 is collated and preferably used for screwing in screws 12 secured in parallel by a plastic retaining strip 14. Such a band 14 is taught in US Pat. No. 4,167,229. The screwdriver 10 includes a chuck 18 that is rotated by a motor (not shown) of the drive unit. The chuck 18 engages the end of an elongated metal shaft 20, best shown in FIG. 3, which is generally composed of a cylindrical metal mandrel 22 with a shaft at the bottom end of the mandrel. The metal bits 24 arranged in a straight line in the direction are detachably attached. At its frontmost end, the bit 24 is formed with a screw tip 23 configured to engage a complementary form of recess 13 formed in the head 16 of the screw 12. As will be described in more detail below, the mandrel 22 holding the bit 24 reciprocates in the guide tube 26 while rotating to engage the subsequent screw 12 and engage that screw into the work piece 28. Screw in. The guide tube 26 is attached to the sliding body 52. The screwdriver 10 of the present invention essentially comprises the same elements as the screwdriver disclosed in US Pat. No. 4,146,071 and screwed in in the same manner as disclosed in this patent. In this regard, as best shown in FIGS. 1, 7 and 8, the screwdriver includes a housing 70 in which the drive (not shown) is secured by its chuck 18. The sliding body 52 is connected to the housing 70 by a shaft 20 so as to be slidably displaced parallel to the vertical axis between the extended position as shown in FIG. 7 and the retracted position shown in FIG. The coil spring 66 urges the sliding body 52 against the housing 70 to its extension position. The sliding body 52 includes a guide channel of a thread strip 14 that carries the screw 12. This guide channel is formed directly under the removable cover plate 72 shown in FIG. 7, and can be removed by the screw 74. This guide channel is best shown in the enlarged front view of the sliding body shown in FIG. 9 with the cover plate 72 removed. In FIG. 9, the groove 76 receives the head of the screw 12 and the top of the screw engages the surface 77. The screw feed advance mechanism is installed within the sliding body 52 and is actuated by the relative motion between the housing 70 and the sliding body 52. In this regard, the claw arms 78 shown in FIGS. 1 and 9 reciprocate back and forth to advance the continuous screw. The claw arm 78 is moved by a mechanical link device having a lever 68, which is of the housing means 70 shown in FIGS. 1 and 7 within a sliding body 52 that reciprocates between an extension position and a retracted position. It is moved by a wheel 80 that engages the ramp 82. The present invention is centered on the guide tube 26. FIG. 2 best shows the first embodiment of the guide tube 26, which has a substantially cylindrical outer surface 27. The cylindrical lumen path, or guideway 32, extends axially through the center of the guide tube 26 and is bordered by a cylindrical side wall 34 that extends radially, and its anterior axial end 36 and its posterior axial end 38. Is open. The guide tube 26 shown in the figure includes a rear portion 40 adjacent to the rear axial end 38 and a front portion 46 adjacent to the anterior axial end 36. At the rear 40 of the guide tube 26, the side wall 34 preferably extends over 360 °. As best shown in FIG. 3, the illustrated front portion 46 comprises an engaging portion 42 and a front portion 44. The front portion 46 comprises an access opening 48 on the right side of the guide tube 26, substantially across its length, as shown in the figure. This access opening 48 extends towards the anterior axial end 36 of the guide tube 26. The screw access opening 48 is sized so that the strip 14 carrying the screw 12 can move inward in the radial direction from the right side into the guide path 32, as shown in several figures. Since the diameter of the screw is preferably slightly smaller than the diameter of the side wall 34, if the head of the screw enters the guideway 32 as a corollary, the screw access opening 48 will have a circumferential spread of at least about 180 °. There must be. If the screw shank enters the guideway, the screw access opening may have a small circumferential spread. The engaging portion 42 of the front portion 46 is a portion where the head of the screw 12 moves when the strip 14 and the screw 12 are advanced. Within the engaging portion 42, the wall 34 of the guide tube 26 engages with the outermost radial edge of the head 16 of the screw 12 and aligns the screw head 16 coaxially and axially within the guide path 32. Align with bit 24 in the axial direction. In this case, within the engaging portion 42, the wall 34 extends around the screw sufficiently to align the head of the screw coaxially. The engaging portion 42 extends around the screw head, preferably at least 120 °, more preferably at least 150 °, and most preferably about 180 °. In the figure, the outlet opening 50 shown on the left side of the guide tube 26 is sized so that the used plastic strip 14'after the screw 12 is screwed can be discharged from the guide path 32. .. As shown in the figure, the side wall 34 of the guide tube 26 continues to provide a side wall 34 that accommodates the screw access opening 48 and the exit opening 50 at the frontmost portion 44 and can guide and assist the head 16 of the screw 12. Therefore, it extends only about 90 ° around the axis of the guide tube 26. FIG. 3 best shows the insertion of the guide tube 26 into the sliding body 52 that supports the guide tube 26. The sliding body 52 is preferably manufactured of plastic by, for example, an injection molding method. The guide tube 26 is detachably mounted in a cylindrical lumen 54 extending through a sliding body 52. When the guide tube 26 is fully inserted and mounted in the lumen 54, the front so that the screw 12 is aligned with the screw access opening 48 and the retaining strip 14 is aligned with the exit opening 50. 46 extends beyond the front of the sliding body to a sufficient distance. As best shown in FIG. 5, it is preferable to select a lumen 54 having a diameter D slightly larger than the outer diameter D'of the guide tube 26. As shown in the figure, the guide tube 26 is attached by a set screw 53 extending into the notch 55 of the guide tube 26 so as not to slide in the axial direction or rotate in the lumen 54. The shaft 20 is configured to be slidably inserted into the cylindrical guideway 32 through the rear axial end 38. As shown in FIGS. 3 and 5, the mandrel 22 and the bit 24, respectively, have a diameter d'larger than the rest of the shaft 20._１It comprises cylindrical portions 62a, 62b, 62c having. Diameter d'of these cylindrical parts_１Is the diameter d of the guideway 32₁Choose slightly smaller. When the shaft 20 is inserted into the guideway 32, these cylindrical portions 62a, 62b, 62c act as positioning portions and engage the side wall 34 to help hold the shaft 20 coaxially aligned with the guide tube 26. The shaft 20 shown in FIG. 3 shows three positioning cylindrical portions 62a, 62b, 62c on both the mandrel 22 and the bit 24, but these positioning portions are not limited to the illustrated form, and other forms and / or It should be understood that the number of positioning parts can be used equally. 4 and 5 are schematic views of a fully assembled guide tube 26, sliding body 52 and mandrel 22 and bit 24. The guide tube 26 and the lumen 54 are substantially aligned in an axial direction, and the guide tube 26 is inserted into the sliding body 52. After the guide tube 26 is inserted, the guide tube is held by the sliding body 52 with the set screw 53 so as not to come off by a normal screwing operation. The guide tube 26 is attached to the sliding body 52, and the mandrel 22 and the bit 24 are aligned with the guide tube 26 and inserted into the cylindrical guide path 32. Inner diameter d of guide tube 26₁The diameter d'of the cylindrical positioning portions 62a, 62b, 62c of the mandrel 22 and bit 24._１A slightly larger selection is made to engage these cylindrical portions 62a, 62b, 62c with the side wall 34, holding the shaft 20 substantially coaxially and in line within the guide tube 26. Maximum diameter d'of cylindrical portions 62a, 62b, 62c_１Is preferably selected approximately equal to the diameter of the head 16 of the screw. As best shown in FIG. 1, the screwed screws 12 are matched and held parallel to each other by the plastic retaining strips 14. If a strip 14 is used for the screwdriver 10, each screw 12a must first be screwed into the work piece 28 by engaging the subsequent screws 12 with the mandrel 22 by the claw arm 78 of the screw feed mechanism. And bit 24 and advance so that they are aligned in the axial direction. This screw feed mechanism engages with and advances the plastic strip 14 when the bit 24 and the mandrel 22 move away from the work piece 28 by the force of the spring 66 in the return process. The screw 12 is moved radially into the guideway 32 through the screw access opening 48. The advanced screw 12a is held in a predetermined position on an axial line with respect to the shaft 20 and the bit 24, and the screw head 16 abuts on the side wall 34 of the engaging portion 42 of the guide path. When the screw 12a moves into the cylindrical guideway 32, the leading portion of the strip 14'where the screw is carried in front of it extends outward from the guideway 32 through the exit opening 50 of the foremost portion 44. The screw 12 and the strip 14 can move forward substantially unimpeded. The diameter of the cylindrical guide path 32 is selected so that the portion of the side wall 34 forming the screw access opening 48 engages with and supports the outermost circumferential surface of the screw head 16. To drive the second strip 14 of the screw 12 with a smaller or larger diameter of the screw head 16, remove the guide tube 26, mandrel 22 and bit 24 and with another guide tube 26'shown in cross section in FIG. replace. The guide tube 26'is similar to the guide tube 26 in that the outer diameter D'is sized to fit into the lumen 54, but the guide path 32'engages with screw heads of different diameters. It is the size to hold this. FIG. 6 shows a guide tube 26'used to screw in a screw 12 having a small diameter of the screw head 16. The guide tube 26 has a diameter d of the guide path 32 by thickening the side wall 34 so that the guide path 32 is slightly larger than the diameter of the small screw head 16._２It is basically the same as the guide tube 26 shown in FIG. 5, except that the size is reduced. The mandrel 22'and bit 24'used within the guide tube 26' have a maximum diameter d'selected to be complementary rotationally engaged to the side wall 34'._２Is almost the same as that shown in FIG. 5, except that is small. With the removable guide tube 26 and the mandrel 22 and bit 24, it is understood that the screwdriver 10 can be used for screws 12 with different diameters of the screw head 16. In this method, no matter what size screw 12 is used, it is always held in line with the shaft 20 in the axial direction by the guide tube 26 of the optimum size. When actuated, the guide tube 26 is inserted into the sliding body 54, the bit 24 with the desired screw tip 23 is inserted into the mandrel 22, and then the guide path from the bit 24 and the mandrel 22 as previously described. 32 Inserted in. Insert some screws 12 matched by the plastic retaining strip 14 into the screwdriver 10. In order to screw the screw 12a into the work piece 28, the drive device is started to rotate the shaft 20. The mandrel 22 and the bit 24 can reciprocate back and forth with respect to the processed material 28 in the guide path 32 while rotating. In the screwing stroke, the user manually presses the mandrel 22 and the bit 24 toward the work piece 28 against the urging of the spring 66, and the sliding body 52 extends with respect to the housing 70. Move to a position retracted from. When the manual pressure is released in the return stroke, the compressed spring 66 returns the sliding body to the extended position, and as a result, the mandrel 22 and the bit 24 recede from the work piece 28 and return to their original positions. In the screwing stroke in which the shaft 20 moves axially toward the workpiece 28, the screwing tip 23 engages with the screw head 16 to rotate the screw 12a. Obviously, the plastic strip 14 is formed to open the screw 12a when it is first rotated by the bit 24. When opening the screw 12a, the plastic strip 14 preferably disengages from the screw 12a and exits through the outlet opening 50 so as not to interfere with the orientation of the screw 12a or its movement into the work piece 28. After the screw 12a is screwed into the work piece 26, the mandrel 22 and the bit 24 move axially away from the work material 28 by the force of the spring 66, and the next screw 12 is moved by the screw feed advance mechanism. , Moves through the screw access opening 48 and aligns axially with the shaft 20. The positioning portions 62a, 62b, 62c are spaced apart along the shaft 20, and when the mandrel 22 and the bit 24 are sufficiently moved toward the workpiece 28, at least one positioning portion 62c is at the rear of the guide tube 26. It is preferably located within 40. In addition to adapting the screwdrivers for use with screws of different screw head sizes, the guide tube also similarly, for example, the length of the front 46 and the placement of the screw access opening 48 and the exit opening 50. By changing, it can be replaced with another guide tube with a front end modified for use with screws of different lengths. A preferred first embodiment of the present invention shows a sliding body 52 having a cylindrical lumen 54 having uniform radial dimensions, but the present invention is not limited thereto. Lumens with varying radial dimensions can also be used with complementary sized guide tubes and screw bits. In a preferred first embodiment, the guide tube 26 is held in the lumen 54 by a set screw 53, but the guide tube is placed in the sliding body, including a key and keyway, a fixing pin, a screw and a sliding shoulder. Other means of removable mounting can also be used. Similarly, other than preventing the guide tube 26 from rotating relative to the sliding body 52, including providing a guide tube that has a polygonal outer surface and fits and engages with a complementary lumen. It should be understood that the means of can be used equally. Installing the removable guide tube 26 is advantageous in extending the life of the screwdriver. Since the guide tube 26 is a portion that wears significantly during use, providing a guide tube 26 that can be replaced separately from the rest of the screwdriver can extend the life of the screwdriver. Further, since the guide tube 26 is replaceable, it is preferably made of a wear resistant material rather than the rest of the sliding body 52. Preferred materials are metal and nylon. The present invention is specifically configured for use with screws having heads within the range of about 1/4 inch or less in diameter. In the present invention, for example, screws of different sizes such as No. 8, No. 10, No. 12 and / or screws of different lengths of 1 inch, 1.5 inch, 2 inch, etc. are screwed into one screw turn, so that different guide paths are used. A screwing means can be provided. 9 and 10 show a second embodiment of the guide tube of the present invention. 9 and 10 show a guide tube 26 similar to the guide tube of FIGS. 1-8, but shorter in length. Throughout these drawings, similar elements are given similar reference numbers. The guide tube 26 is configured to be attached to the lumen 54 of the sliding body 52, in which case each has a complementary form. In order to place the guide tube 26 in the lumen so that it does not rotate in the axial direction, one side of the guide tube has a flat outer surface 79, and the other part corresponds to the lumen 54 which is almost cylindrical. Match with the flat surface 81. The outer surface of this guide tube is in a gradual form, with a reduced diameter rear 82 and a larger diameter main portion 83, between these portions with a rearward facing shoulder 84. The lumen 54 is also formed to axially position the guide tube, as best shown in FIG. 10, where the lumen 54 has a corresponding anteriorly oriented shoulder portion 85. As shown in FIG. 9, the groove hole 86 is cut into the guide tube, the rearmost corner on the left side of the cover plate 72 shown in FIG. 7 is fitted into the groove hole, and the cover plate is mounted in a predetermined position. Hold the guided guide tube 26. The guide tube 26 of FIGS. 9 and 10 has a shorter rear portion 40 than the guide tube 26 of FIG. The rear inner side wall 34 holds a cylindrical mandrel 22 having a continuous cylindrical outer surface as shown in FIG. The guide tube 26 of FIG. 9 holds the mandrel 22 in the lumen 54 at a distance from its wall. The guide tube 26 shown in FIGS. 9 and 10 includes a front portion 46 having an internal side wall 34'with a diameter larger than the inner diameter of the rear side wall 34. The diameter of its front 46 is shown large so that fasteners that require a socket 90 or bit whose head diameter is greater than the mandrel diameter, or whose diameter is greater than the mandrel diameter, can be screwed in. ing. The embodiment shown in FIG. 10 is configured to screw in a screw 12 of a hexagonal head having an integral circular metal washer 13 arranged on a strip 14. The washer 13 is slightly smaller in diameter than the diameter of the inner side wall 34'as shown, so that the engagement of the side wall 34'and the washer 13 causes the screw 12 to be coaxially placed within the guide tube 26. .. FIG. 10 shows a mandrel 22 having a socket 90 that engages the hexagonal head of the screw 12. Its extended diameter side wall 34'extends posteriorly beyond the screw access opening 48 so that the socket 90 can be pulled posteriorly behind each screw that is screwed in. FIG. 11 shows the same guide tube 26 as shown in FIGS. 9 and 10, except that the guide tubes are shown to have different inner diameters. The guide tube 26 shown in FIG. 11 has a constant inner diameter slightly larger than both the similarly sized screw 12 head to be screwed in and the mandrel selected to be preferably the same diameter as the screw head. There is. As can be seen in the embodiments shown in FIGS. 10 and 11, it is necessary to change the screwdriver from, for example, screwing the type of screw shown in FIG. 10 to screwing the type of screw shown in FIG. All you have to do is remove the cover plate, remove the first guide tube, install the second guide tube, reattach the cover plate, and then install the new bit. No substantial disassembly is required to remove and replace the guide tube, and there is no need to disassemble the sliding body for the drive, housing or spring. The axial length of the guide tube 26 is chosen to be shorter than the distance between the open end of the lumen 54 and the tip plate 90 shown in FIG. 7, which is useful for easy removal and mounting without disassembly. It is preferable to do so. Although the present invention has been described by preferred embodiments, the invention is not limited by these embodiments. Many variations will come to mind for those skilled in the art. The definition of the present invention is made within the scope of the claims described below.

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