Tool changing device for a machine tool.

The invention relates to a tool changing device for a machine tool, with a provided on the machine tool toolholder receptacle, in particular a spindle, which can be used with the tool holder receptacle, a tool supporting the tool holder, with a those detected when changing tools changer and an automatic operating device, the clamping device a for compound of the tool holder is actuated with the tool holder receiving means, wherein the tool holder has a cylindrical portion to the attack of the changing arm and in the axial direction of this cylindrical portion is inserted into the tool holder support.

With such a well-known tool changing system (DE-AS 16 52 699) are oppositely provided on a common pivot shaft diametrically two alternating arms. Each of these change arms includes at its end a semi-cylindrical bearing shell, whose inner diameter corresponds approximately to the outer diameter of the cylindrical portion. Opposite this bush a movable approximately in the longitudinal direction of the changing arm locking bar is arranged on the changing arm. For the tool change the changer is in the region of the tool holder support_- acquisition pivoted, said he and his semi-cylindrical shell comprises the cylindrical portion of the tool to be partially. In this case, the lock bar deviates back against the force of a spring and then pressed, when the semi-cylindrical shell abuts against the cylindrical portion, opposite to one of the semi-cylindrical shell body on the cylindrical portion. This type of support is not sufficiently accurate, if you want to replace tools whose tool holder fits very snugly into the toolholder receptacle. In addition, the change arm in the area of ​​semi-cylindrical shell has relatively large construction dimensions, so that the tools in a tool magazine, in which they are passed by the changing arm, must be located at a greater distance from one another. The tool magazine has consequently relatively large dimensions. In order for the tool to be replaced holder in its axial direction in a specific position relative to the change arm assumes all risks of unexpected shifts when changing over the change arm, it is also necessary that shoulders are present in the axial direction upstream and downstream of the cylindrical portion, which are smaller in diameter than the said cylindrical portion. The change accordingly has both sides of the semi-cylindrical shell portions, which diameter is also slightly smaller than the diameter of the semi-cylindrical shell. Due to the shoulders of the tool holder is weakened in its cross-section or, if one wants to avoid a cross-sectional weakening, it is necessary to make the semi-cylindrical portion in the diameter correspondingly greater, which in turn makes it necessary that the tool holders are arranged in the magazine with even larger mutual distances.

The most common type of tool changing devices working with tongs-like grippers, which are each provided at the end of the changing arm. The tool holder has a flange, in which a groove is inserted with a trapezoidal cross-section. In this groove, the tongs of the gripper engage. Again, the connection between gripper and tool holder is relatively inaccurate. Furthermore, the grippers and the required flange have the already above-mentioned drawback of the tool holder must be positioned at a relatively large distance apart in the magazine.

The invention is therefore based on the object to provide a tool changing device for a machine tool of the type mentioned, which allows avoiding the above disadvantages, a very accurate positioning connection between tool holder and change arm that is simple in construction, the small even in the region in particular the replaceable head construction dimensions , and wherein the tool holder must have no diameter enlargements to attack the changing arm, so that the tool holder can be arranged in a tool magazine with the smallest possible mutual distance.

A first solution of this object is inventively in that a radially extending threaded bore is provided in the cylindrical portion, that at the free end of the changing arm is provided a radially movable to the axis of the cylindrical portion replaceable head, the prism-shaped at its tool holder facing outer end with at least one centering is provided that in the changing head a in the center of the centering in the radial BEWE movement direction of the replaceable head extending in two opposite directions of rotation by motor drivable connecting pin is provided which is limited in its axial direction in the replaceable head slidably and at its free end into the threaded bore matching external thread.

A second object is achieved according to the invention is that a radially extending threaded bore is provided in the cylindrical portion, in which an entity belonging to the clamping device clamping screw is screwed that one is provided radially to the axis of the cylindrical portion movable alternating head at the free end of the changing arm, the facing at its, the tool holder, the outer end with at least one prism-shaped centering provided recess may be that in the interchangeable head, a motor-drivable in two opposite directions of rotation screwdriver in the radial direction of movement of the replaceable head is displaced, one cooperating at its free end with the clamping screw, comprises in the center of the centering recess provided for entrainment in that in the interchangeable head concentrically surrounds the screwdriver threaded bush is provided which has a fitting to the clamping screw internal thread, and in the radial direction of movement of the interchangeable head in this displaceably mounted-is, and that the threaded bush in the direction loaded on the outer end of the changing head by a spring and in the opposite direction by a driving device is movable.

Both solutions of the task allow very accurate positioning connection between the tool holder and the replaceable head, because both parts are securely bolted together by means of Uerbindungsbolzens or belonging to the clamping device clamping screw when switching operation. The positional accuracy between the two parts will become crucial also ensured by the prism-shaped recess of the replaceable head. Furthermore, both embodiments the advantage is common that the tool holder need only have the cylindrical portion and to the attack of the changing arm is required to have no further projecting over the diameter of the cylindrical portion, or also smaller in diameter parts. Further, since the interchangeable head acts only from one side to the tool holder, is the side of the tool holder no place for the changer or parts thereof requires the use of the tool holder in a tool magazine or in the toolholder receptacle. As a result, the tool holder can be arranged at a very small mutual distances in the magazine, wherein the pitch of the magazine needs to be only slightly larger than the diameter of the cylindrical portion. Furthermore, the tool holder is not weakened by any grooves or shoulders so that the tool holder is extremely stable. By positionally accurate connection between the interchangeable head and tool holder can also toolholder to be inserted with very tight fit in a tool holder receptacle, be changed easily. Moreover, the new tool changing device for all connection systems between the tool holder and tool holder receiving is applicable.

Further advantageous embodiments of the solutions according to the invention are characterized in the subclaims.

The invention is further illustrated in the following, illustrated in the drawing with reference to several embodiments.

Show it:<ul><li>1 shows a first embodiment in longitudinal section,</li><li>2 shows a cross section along the line II-II of Figure 1,</li><li>3 shows a second embodiment in longitudinal section;</li><li>Figure 4 is a plan view of the replaceable head in direction IV of Figure 5,</li><li>5 shows a cross section along the line VV of Figure 3,</li><li>6 shows a further embodiment in longitudinal section.</li></ul>

The connection between tool holder and tool holder receptacle will be explained in the following, with reference to a tool holder housing-forming machine tool spindle. 1

The machine tool spindle 1 is rotatably supported in the headstock. 2 It has at its front free end on a toolholder receptacle 3 for the tool holder. 4 The tool holder 4 carries at its free, not shown (in Figure 1 left) end of a drill bit, a boring tool, a cutter, a reamer od. Like., Which are optionally fixedly or interchangeably and with the interposition of spacers with the tool holder 4 , The tool holder 4 has a very slight play (practically without play) into the mounting hole 5 of the toolholder receptacle 3 matching, cylindrical shank. 6 In the cylindrical shaft 6, a transverse hole 7 is arranged, in which a cylindrical clamping pin 8 is mounted slidably. This clamping bolt 8 has at one end a conical recess and at its other end a tapered neck. In the tool holder receiving two diametrically opposite, radially extending internal thread are provided, in each of which a clamping screw 9, 10 is screwed. The clamping screw 9 engages with a cone-shaped projection in the clamping bolt 8, while the clamping screw 10 is provided with a conical recess into which engages the clamping bolt. The axes of the clamping screws 9, and 1G. that of the clamping bolt 8 are offset from each other, when tightening DA8 one of the clamping screws 9, 10, the annular surface 11 of the tool holder 4 is pressed against the end face 12 of the spindle the first

For the tool change so a loosening and tightening the clamping screw 9 is required. For this to be done automatically, the spindle must be 1 so stopped that the clamping screw 7 is always in the same place. As an actuating device for the clamping screw 9, a screw 13 is provided which is displaceable in the direction of the clamping screw axis in the housing fourteenth The housing 14 is connected via a bracket 14a fixed to the headstock. 2 The screwdriver 13 has at its free end on a carrier 15, which fits into the clamping screw. 9 The screwdriver 13 is also driven about its axis in two opposite directions of rotation by an electric motor, not shown.

On the tool holder 4 further comprises a cylindrical portion 4a is provided which has a radially to the axis S of the cylindrical portion extending threaded bore sixteenth

At the free end of a changing arm not shown in the drawing, which is radially in direction V to the axis S of the cylindrical portion 4a movable, a replaceable head 17 is provided facing to his, the tool holder 4, the end of a prism-shaped centering recess having 18th The apex line 18a of the prism-shaped recess extends parallel to the axis S.

In the center of the centering recess 18, ie in the region of the apex line 18a, a connecting bolt 19 is provided which extends in the direction of the radial direction of movement V of the Wechselkofes 17th The Verbindungebolzen 19 is mounted in a hole 20 of the replaceable head 17 radially of the cylindrical projection 4a limited extent. The connecting pin 19, which is formed in the embodiment shown as a cylinder head bolt, has a formed by its head 19a Bund 21st Following the bore 20 an annular shoulder 22 is provided, which is limited by the displacement movement of the connecting pin 19 in the direction of the centering recess 18 side.

The connecting bolt 19 has at its free end a cylindrical guide projection 19b, whose diameter is slightly smaller than the inner diameter of the threaded bore 16. Besides, the external thread 19c of the connection pin 19 fits into the threaded bore sixteenth

In the interchangeable head 17 coaxially arranged further to the connecting pin 19 of the shaft 23 of a motor-driven in two opposite directions of rotation laws screwdriver. This shaft 23 engages with a catch 24 in the screw head 19a. The shaft 23 also has a collar 25, on which a compression spring is supported 26th Through this compression spring, the shaft 23 and hence, the connecting bolt 19 is loaded in the direction towards the outer end of the replaceable head 17 out so that the connecting pin 19 and hence the shaft 23 against the force of the spring 26 are movable in the interchangeable head 17 inside.

Optionally, the connecting pin 19 and the shaft 23 could also consist of a piece, in which case the spring 26 would be arranged at a suitable location.

For the tool change, the spindle 1 is stopped, that the clamping screw 9 the catch 15 is facing. The replaceable head 17 is moved radially by the change arm to the axis S in the direction U, wherein the free end of the connecting pin 19 under the action of the spring 26 through. the centering recess 18 protrudes. The centering recess 18 is brought to the cylindrical portion 4a to the plant, which first enters only the cylindrical portion 19b of the connecting bolt 19 into the threaded bore sixteenth Moreover, the connecting pin is in move 19 against the force of spring 26 in the replaceable head 17th If now the Schraubendreherschaft.23 driven in right direction of rotation, then the connecting bolt screwed with its external thread 19c into the threaded hole 16, until its collar 21 comes to the ring shoulder 22 into contact. Tool holder 4 and Wechsalkopf 17 are then connected together with positional accuracy over the connecting bolt 19th

By compressed air, the screwdriver shaft 13 with its catch 15 moved into the clamping screw 9, and then driven in the left direction of rotation. Hereby, the clamping screw 9 screwed radially outwards and the tensioning device between the tool holder 4 and work tool holder shot 3 is solved.

The changing head 17, which is screwed thereto tool holder 4 is now moved in the direction A, to the cylindrical shaft is 6 vallständig stepped out of the receiving bore. 5 By moving the replaceable head 17 against the arrow V and subsequent pivotal movement now the tool to be replaced holder 4 can be moved out of the area of ​​the spindle. Meanwhile, an identical Enriched replaceable head 17 that is disposed opposite the replaceable head shown diametrically to the changing arm, connected in the region of the tool magazine with another tool holder, which is pivoted now in the region of the spindle 1 and moved radially toward V. As soon as the axis of the shaft 6 with the axis of the mounting hole 5 is aligned, there is a shift of the replaceable head 17 opposite of the arrow A, whereby the shaft 6 is inserted into the receiving bore fifth the clamping screw is then tightened again 9 and the connecting pin 19 is screwed out of the threaded bore 16 by means of the screwdriver. 13 After moving back the replaceable head 17 against the arrow V of the change process is completed.

In the embodiment shown in Figures 3 and 4, the machine tool spindle 1 is rotatably supported in the headstock. 2 It has at its front free end a tool holder receptacle 31 for the toolholder 30th The tool holder has at its end facing the spindle in a cylindrical portion 30a has a cylindrical mounting hole 32 with two diametrically opposed, radially extending internal threads in each of which a clamping screw 34, 35 is radially screwed. The tool holder 30 carries at its free end 30b, for example, a drill bit, a boring tool, a cutter, a reamer or the like. That are fixed or interchangeable, possibly also connected with the interposition of intermediate pieces to the tool holder 30.

The toolholder receptacle 31 has a in the receiving bore 32 with very little play (practically without play) matching cylindrical shank 36th

In the cylindrical shaft 36 has a transverse bore 37 is provided, in which a cylindrical clamping pin 38 is radially slidably. This clamping bolt 38 has at its one end to a conical neck and at its other end a conical recess, in which engage the locking screws 34, 35th

At the free end of the changing arm 52 which can be pivoted at its center around an axis extending parallel to the spindle axis, a replaceable head is radially displaceably mounted in direction V 39 to the axis of the cylindrical portion 30a. For sliding bearing used in the present case two rods 40, which engage in corresponding guide holes 41 of the replaceable head. 39 but it can also have any other straight guide can be used.

The changing head 39 has at its outer, the tool holder 30 facing the end, a first prism-shaped centering recess 42, whose apex line runs 42a parallel to the axis S of the cylindrical portion 30a and the axis of the tool holder 3D. Making the switch head can also accommodate toolholder without rotary movement, rotated its axis by 90 ° is disposed to the axis of the tool holder 30, has the replaceable head 39 also have a second, extending perpendicular to the first centering 65 centering 43 on whose crest line 43a perpendicular to apex line 42a runs.

In the change head 39, a screwdriver 44 is further arranged which is driven by a motor in two opposite directions of rotation. The screwdriver 44 has at its free end to a matching in the clamping screw 34 catches 45th The carrier 45 is arranged in the center of the centering recess 42 and 43rd The screwdriver 44 has a cylindrical stem 44a which is surrounded by a piston 47 concentrically. This piston 47 is displaced in a sunken in the replaceable head 39 cylinder 48th Thus the entire screwdriver 44 is in the direction V, ie 39, perpendicularly to the direction of displacement of the interchangeable head in the direction of its axis to the axis of the cylindrical portion 30a.

In the interchangeable head 39 a threaded bushing 46 is provided which surrounds the screwdriver 44 concentrically. The threaded bushing 46 has a fitting to the clamping screw 34 female thread 46a. The threaded bushing 46 is mounted in the interchangeable head 39 in the direction of displacement V of the replaceable head 39 slidably. The threaded bush 46 is further loaded by a spring 49 toward the outer end of the replaceable head. 39 Thus it can be moved against the pressure of spring 49, a drive device in the form of the threaded bushing 46 concentrically surrounds the piston 50 is provided which is slidably mounted in a respective cylinder chamber 51 of the replaceable head. 39

In Figure 3, the toolholder 30 and the toolholder receptacle 31 are illustrated in strained operating position. For the tool change, the spindle 1 is stopped in a predetermined position and the change arm 52 is pivoted to a position in which aligns the axis of the screwdriver 44 about the axis of the clamping screw 34th The changing head 39 is then hydraulically, pneumatically or mechanically moved in the direction V on the tool holder 30, to its prismatic centering 42 comes to the cylindrical portion 30a of the tool holder 30 for installation and thereby against this centered. By means of the piston 47 of the Schraubendreher44 is shifted in the direction of the clamping screw 34 and simultaneously driven in the left direction of rotation. His driver 45 penetrates into the driver opening the clamping screw 34th Subsequently, the drive shaft rotates the screwdriver 44 in the left direction of rotation, whereby the clamping screw 34 with respect to the mounting hole 32 moves radially outward. The clamping screw 34 screwed to the same time in the internal thread 46a of the threaded bushing 46 a. In order that the screw thread does not undergo forced at the start of the screwing, the threaded bush is under moderate pressure of the spring 49. If the clamping screw 34 is screwed about half their length in the threaded bush 46, so the hydraulic oil in the cylinder chamber 51a is pressurized, whereby the threaded bushing is moved against the direction of the arrow V 46th Since the tool holder 30 is connected via the clamping screw 34 with the threaded bushing 46, thus the tool holder 30 is firmly fixed to the replaceable head 39, where he is also aligned by the centering 42nd The tool holder and the tool carried by it remain aligned absolutely exactly opposite the replaceable head 39 also at greater length and greater weight. It is particularly advantageous that all the forces between the tool holder 30 and the replaceable head 39 are closed and the outside have no effect. Thus, the system tool holder 30 and the replaceable head 39 is in equilibrium.

Once the tool holder 30 and the replaceable head 39 are firmly clamped together, the change arm 52 is moved in the axial direction of the spindle 1 according to Figure 1 to the left, whereby the tool holder 30 is removed from the shaft 36th Subsequently, the change arm can pivot 52 and the toolholder 30 passed a magazine not shown. At the same time by a second change arm, which is formed just as the change arm described, and is arranged to be diametrically opposite, another tool holder pushed up on the shaft 36th Meanwhile screwdriver goes into the clamping screw 34 in the opposite direction of rotation right, whereby the connection between the interchangeable head and tool holder is released again and the tool holder is again firmly fixed to the toolholder receptacle. After the change head was against the arrow V is returned to its initial position 39, the tool change is completed.

In the embodiment shown in Figure 6, the tool holder 53 also has a cylindrical receiving bore 54 which aufschiebbarrist exact match to the connected to the spindle 1 cylindrical pin 55th The tool holder 53 has in this case a cylindrical portion 53a, which is provided with a threaded hole 56th In this threaded hole, a clamping screw 57 is screwed which engages with a cone-shaped projection 58 in a conical bore 59 of the spigot 55th The changing head 39 ', the screwdriver 44' with its carrier 45 'and the threaded bushing 46' are formed in the same manner as the corresponding parts in the previously described embodiment according to Figures 3 - 5. In order to avoid repetition, therefore, with respect to closer referenced embodiments to the above description. Also in this case 'the clamping screw 57 and dissolved in the internal thread 46'A of the threaded bush 46' is threaded in the rotational movement of the screwdriver 44th