WO1995017273A1

WO1995017273A1 - Process and device for producing tool bits

Info

Publication number: WO1995017273A1
Application number: PCT/EP1994/003922
Authority: WO
Inventors: Trong-Hoang Do; Armin Schuster
Original assignee: Swg Schraubenwerk Gaisbach Gmbh & Co. Kg
Priority date: 1993-12-23
Filing date: 1994-11-26
Publication date: 1995-06-29
Also published as: AU1240595A; DE4344194A1

Abstract

A process and device for producing tool bits with an especially hexagonal shaft by means of a profiled wire (1) with the corresponding polygonal section as the initial material. The profiled wire (1) is cut into blanks (9) of a given length. The polygonal blanks (9) are fully forward-extruded in a multi-stage press, whereby in an initial step a cone (18) is first formed on the still-hexagonal face of the blank (9). This provides a circular face with a conical transition to the hexagonal shaft. In a second step, the frontal region with the cone (18) is extruded into a smaller-diameter cylindrical section (25). In a third step the face of the cylindrical section is coned, and in a fourth the actual shape (30) is obtained by extrusion.

Description

Description:

Method and device for producing tool bits

Tool bits generally have a hexagonal shank that is inserted into a bit holder of a tool. The free end is then designed, for example, as a Phillips screwdriver or has another shape intended for actuating screws or the like.

At the moment, tool bits of this type are normally first machined and then provided with the special shape.

It is already known (DE 42 07 963 AI) to produce tool bits from a round wire by cold working. First of all, a thickened section must be formed on the cylindrical blank, which is then shaped into a hexagon shape for the shaft of the bit.

This is followed by machining to produce a coupling and only then is the free end cold-formed by a plurality of press jaws which can be moved radially inwards.

The invention is based on the object of providing a method for producing a tool bit and a device for carrying out this method, with which bits can be produced with consistently high accuracy of the dimension and at the same time maintaining symmetry with the longitudinal axis.

To achieve this object, the invention proposes a method with the features of claim 1 and a device with the features of claim 10. Further developments are the subject of the respective subclaims.

The use of closed dies enables the desired dimensions and the desired symmetry to be maintained with much greater accuracy than the use of movable press jaws. The use of a multi-edged profile wire in the initial state, for example hexagonal, means that no separate process step is required to produce the shaft section.

The extrusion for forming a hexagonal blank into a section with a generally cylindrical configuration that deviates from this hexagonal shape is only made possible by the preceding process step of pressing on a coupling. The coupling in turn takes place according to the invention by pressing in a closed die. Overall, this means that the tool bits can be produced by a series of successive extrusion processes in a multi-stage press without other machining operations being necessary in between.

For further improvement can be provided according to the invention that before the extrusion of the final profile End face of the cylindrical section is chamfered or coupled by extrusion. This also facilitates and improves the process of finally producing the profile by extrusion.

This coupling of the cylindrical section can also take place in a separate, closed die.

The invention proposes, when extruding the profile section, first to make it longer than desired and to bring it to the desired length and shape in a subsequent process step. Particularly in the case of very small dimensions, this ensures that the shape of the profile is completely formed up to the front end face in the case of a shape which may be disadvantageous in terms of production technology.

According to the invention, it can be provided that after the production of the tool bit by extrusion, a chamfer is subsequently attached to the shank section and / or a groove for the snap ring is attached in a tool holder for fixing the tool. This can be done, for example, at the same time as the above-mentioned method step of finally machining the front end face of the tool.

According to the invention, it can be provided that the wire is angularly aligned before being cut to length. This means that the profile wire can be divided into the individual blanks with greater accuracy, so that the end faces of the blanks run almost completely flat.

According to the invention, it can be provided in a further development that the alignment of the wire and the blanks during the driving is maintained. This can be done, for example, by gripping the blanks by a gripper at their hexagonal section and transporting them to the individual dies. No further alignment is then necessary, since the matrices are normally fixed and also aligned.

According to the invention, it can be provided that the extrusion takes place solely by axial pressure, for which purpose a stamp can be used, for example, which presses the blank into the shape of the die.

According to the invention, it can be provided in a further development that the profile wire is calibrated before being cut to length. This may be necessary because the profile wire is on

Coils are delivered wound and it is quite possible that there are small kinks in the wire.

The device proposed by the invention contains a multi-stage press with individual work stations, each of which is constructed similarly or identically and in which the individual closed dies have shapes that correspond to the shape of the blank that is to be produced at this work station. The term "closed" is intended to mean that the manufacturing process of the blank is carried out entirely in a die. With hexagonal blanks, the shape of the die is also a hexagon.

According to the invention, it can be provided that the cross-sectional shape of the stamp corresponds to the cross-sectional shape of the shaft of the blank. For example, in the case of a hexagonal shaft, the punch can also be hexagonal, its side length and its cross-sectional dimension being selected such that it can still be easily inserted into the shape of the die. It will in this way it is ensured that the extrusion is carried out only on the opposite side of the blank. When using a stamp that does not match the shape, a burr can arise on the circumference of the hexagonal shaft of the bit, which can lead to difficulties during the re-turning operation.

According to the invention, it can be provided that the drive device moves the punches of several, preferably all, work stations together. This applies in particular if the matrices of all workstations are arranged immovably next to one another. In this multi-stage press with several workstations, a blank is machined at every cycle in each workstation, with the blanks then being transported from one station to the next in cycles. So that the introduction of the blanks or the partially machined blanks into the individual dies can be carried out simply and quickly, it can be provided that the transport device transports the blanks in an aligned manner to and from the work stations.

The device can be designed so that it works from polygonal blanks. However, it is particularly favorable if it has a drawing-in device for drawing in and moving a polygonal profile wire and a separating device for separating individual blanks from the profile wire. No separate production of blanks is then required.

In particular, it can be provided that the pull-in device has at least one profiled roller for angularly aligned insertion of the profile wire into the separating device. The consequence of this is that the separating device can be designed such that it produces the end faces of the separated individual blanks exactly in a plane perpendicular to the longitudinal direction.

It can be provided that the separating device has a fixed knife bushing and a knife which can be moved transversely to the longitudinal direction of the profile wire, both of which have a through opening for the wire with a shape corresponding to the cross section of the wire. When the profile wire is sheared off, both the part held by the bushing and the part sheared off by the knife are held along its entire circumference, so that exact cutting planes result.

The invention can have an alignment device for angular alignment of the profile wire before it is cut off. This then makes it possible to use wire spools in which the wire is wound in any orientation.

According to the invention, the die of a work station, namely the first work station, has the shape of the polygonal blank with a coupling on its one end face.

Then the die that follows as work progresses can have the inner shape of a polygonal blank provided with a cylindrical section.

In a further development, a third work station can have the shape of a polygonal blank provided with a cylindrical section and a coupling at its free end.

Further features, details and advantages result from the patent claims, the wording of which by reference to Contents of the description is made, the following description of a preferred embodiment of the invention and with reference to the drawing. Here show:

Figure 1 shows schematically the manufacture of individual blanks from a polygonal profile wire.

Fig. 2 shows the various work stations

Multiple press for the production of tool bits according to the method proposed by the invention;

3 shows a section through the arrangement of FIG. 1 along line III-III;

Fig. 4 shows a section through the arrangement of Fig. 1 along line IV-IV.

In the plan view of FIG. 1, a polygonal profile wire 1 is moved from left to right from a supply spool (not shown) with the aid of straightening rollers 2 and feed rollers 3. The straightening rollers, whose axis of rotation in FIG. 1 run perpendicular to the plane of the drawing, engage the profile wire 1 in the region of its edges.

The feed roller 3 rotates about the axis indicated by the stub shaft 5 and has a groove 4 which is approximately trapezoidal. This groove 4 is adapted to the shape of the profile wire 1. Rolls 2 and 3 pull the wire and push it to the right of roll 3 to the separating device 6 shown on the right in FIG. 1. The actual abutment is in direct contact with the knife bushing 7. Shear knife 8 is arranged, which also has a passage opening, the shape of which corresponds to the cross section of the profile wire 1. The profile wire 1 is therefore encompassed on both sides in the socket 7 and in the knife 8. The shearing knife 8 can be moved from bottom to top perpendicular to the plane of the drawing transversely to the longitudinal direction of the profile wire 1. During this movement, the profile wire 1 is sheared off at the point of separation between the two parts 7, 8 of the separating device 6, the profile wire being guided along its entire circumference through the opening of the two

Parts 7, 8 of the separation device 6 gives a smoothly aligned parting plane. After the shearing has been carried out, a blank 9 is formed, which is gripped by a gripping device and moved to the work stations shown in FIG. 2. The gripping device is preferably designed such that the orientation of the blank 9 is not changed, so that its angular orientation about its own longitudinal axis is retained.

Figure 1 is shown schematically; in the embodiment actually used, the movement of the profiled wire takes place from right to left relative to the arrangement shown in FIG. 2.

The blank 9 shown at the top in FIG. 2 has a shape which corresponds to the cross-sectional shape of the later hexagonal shank of the tool bit to be produced.

2 shows a series of closed dies 10 to 13, which are closed during the production process of the tool bits. In the first die 10 in the working direction, the die shape 14 is shown in solid lines. The insertion area 15 and a channel 16 arranged on the opposite side are shown in dashed lines an ejector can pass through to eject the blank 9.

The actual shape 14 has a hexagonal section 17, at the end of which is directed further into the interior of the die 10, a conical coupling 18 is arranged. The blank 9 is axially inserted into the die 10 from the position shown. This takes place with an axial effort using a stamp 19 which is arranged on a slide element 20 designed as a stamp block. The stamp 19 is shown with a hexagon shape. Since the deformation in this die 10 is only slight, a stamp 19 with a round cross section can also be used at this point. The slide element 20 is moved in the direction of arrow 21 by a drive device and presses the blank 9 into the interior of the mold 14. The length of the stamp 19 and the stroke of the slide element 20 are selected such that the free end face 22 of the stamp 19 at the end of the stroke runs flush with the outer end face of the hexagonal section 17 of the mold 14 that can be seen on the right. The Stamp

19 thus engages through the insertion area 15 into the die 10. During this pressing-in, a coupling, that is to say an approximately conical region, is pressed on the free end face 23 of the blank 9, so that the end face of the blank 9 then formed is delimited by a circular cone jacket.

The coupling is preferably dimensioned such that the end face, which is now circularly limited, has a diameter which is essentially the same as the diameter of the cylindrical section to be produced in the next method step. After this method step has been carried out, the slide element 20 with the plunger 19 is moved back into the starting position shown and the blank 9 now provided with the coupling is ejected from the die 10 again with the aid of an ejector. It is then gripped by a gripper and moved in the direction of the die 11. The same process is repeated there. A punch 27 with a hexagonal shape presses the coupled blank 9 into the inner shape of the die 11. Since a large deformation is carried out in this die, the hexagonal shape is preferred at this point. Only the part of the inner shape which the blank 9 is to assume by extrusion is shown in the die 11. This shape in turn contains a hexagon area 24, which is now shortened, to which a cylindrical section 25 with a reduced diameter is connected via the conical surface 18. After performing the extrusion process in the die 11, the slide element 26 for the punch 27 is moved back again and the blank 9 is pushed out by the ejector. The diameter of the cylindrical section is chosen so that it corresponds to the outer diameter of the desired profile section.

The gripper now moves the blank 9 to the die 12, where the process of extrusion is repeated. Here the cylindrical region 25 of the shape contains a front conical surface 28. A coupling or chamfering of the front end edge of the cylindrical section is therefore carried out again. The stamp on this die 12 can again have a round cross-sectional shape.

In the last die 13, the front section 29 now has the profile shape of the desired tool shape, the section 29 being somewhat longer than the end result actually desired. This ensures that the individual, radially outwardly projecting projections 30, which form the rotary drive of the tool, are completely formed right up to the front.

After the blank 9 has been ejected from the die 13, the tip is then machined to, for example, 140 ° on an automatic lathe, and at the same time the rear end face 31 of the blank can also be provided with a chamfer.

The tool bit now produced can then still be treated in the usual way, for example hardened or stripped.

3 shows the engagement of two opposing straightening rollers 2 on the two opposing edges of the profiled wire 1. Both straightening rollers 2 have a groove with a V-shaped cross section, the flanks of which enclose an angle of 120 ° between them, which is the inside angle corresponds to the cross section of the profile wire 1. The straightening rollers 2 rotate around the indicated bearing shafts 32 and are driven in some way.

4 shows the engagement of two feed rollers 3 on the sides of the profile wire 1. The cross-section trapezoidal groove 4 contains a bottom 33, the axial length of the edge length of the cross section of the profile wire 1 is equal, the two flanks 34 of the groove 4 extending at an angle of 120 ° with respect to the bottom 33, so that the roller 3 on the profile wire 1 attacks on three of its side surfaces.

Claims

Claims;

1. A method for producing tool bits with a polygonal shank by cold forming, wherein

1.1 a polygonal profile wire (1) is cut into pieces of a certain length to form blanks (9),

1.2 the blank (9) is extruded in a first closed die (10) to form a coupling (18) on its front end face (23),

1.3 the polygonal shaft of the blank (9) is extruded over a part of its length in a cylindrical section in a second closed die (11) and 1.4 the cylindrical section is extruded into the desired profile shape in a further closed die (13).

2. The method according to claim 1, wherein before the extrusion of the final profile, the end face of the cylindrical portion is chamfered or coupled by extrusion.

A method according to claim 2, wherein the coupling of the cylindrical section takes place in its own closed matrix (12).

Method according to one of the preceding claims, wherein the profile section is formed longer than desired in the last extrusion and is machined to the desired length and shape in a subsequent step.

Method according to one of the preceding claims, wherein "after the extrusion" a chamfer is attached to the free end (31) of the shaft section and / or a groove for a snap ring.

Method according to one of the preceding claims, wherein the profile wire (1) is angularly aligned prior to being cut to length.

7. The method of claim 6, wherein the orientation of the

Profile wire (1) and the blank (9) is maintained during the process.

8. The method according to any one of the preceding claims, wherein the pressing is carried out by axially acting pressure.

9. The method according to any one of the preceding claims, wherein the profile wire (1) is calibrated before cutting.

10. Device for producing tool bits with a polygonal shaft, in particular for carrying out the method according to one of the preceding claims, with 10.1 a plurality of workstations, each 10.1.1 a closed die (10 to 13) with a shape corresponding to the desired shape of the blank (9) at this stage,

10.1.2 a punch (19, 27) for pressing the blank (9) into the die (10 to 13),

10.1.3 an ejector for the extruded blank (9) and

10.1.4 have a drive device for the relative movement between punch (19, 27) and die (10 to 13), and with

10.2 a transport device for transporting the blank (9) between the work stations.

11. The device according to claim 10, wherein the cross-sectional shape of the stamp (19, 27) at at least one work station corresponds to the cross-sectional shape of the shaft of the blank (9).

12. The apparatus of claim 10 or 11, wherein the drive device moves the stamp (19, 27) of several, preferably all, workstations together.

13. Device according to one of claims 10 to 12, in which the matrices (10 to 13) of all workstations are arranged immovably aligned next to one another.

14. Device according to one of claims 10 to 13, wherein the transport device, the blanks (9) aligned to and transported from the workstations.

15. Device according to one of claims 10 to 14, with 15.1 a pull-in device for pulling in and moving forward a polygonal profile wire (1) and 15.2 a separating device (6) for separating individual blanks (9) from the profiled wire (1).

16. The apparatus of claim 15, wherein the feed device has at least one profiled roller (2, 3) for angularly aligned insertion of the profile wire (1) into the separating device (6).

17. Device according to one of claims 10 to 16, wherein the separating device (6) has a fixed Messer¬ bushing (7) and a transverse to the longitudinal direction of the Profil¬ wire (1) movable knife (8), both of which have a through opening for have the profile wire (1) with a shape corresponding to the cross section of the profile wire (1).

18. Device according to one of claims 10 to 17, with an alignment device for angular alignment of the profile wire (1) in front of the separating device (6).

19. Device according to one of claims 10 to 18, wherein a die (10) has the shape of the polygonal blank (9) with a coupling (18) on its end face (23).

20. Device according to one of claims 10 to 19, wherein a die (11) has the shape of a polygonal blank (9) provided with a cylindrical section.

21. The device according to one of claims 10 to 20, wherein a die (12) in the form of a polygonal, with a cylindrical portion and a coupling to the Free end of the cylindrical section provided blank (9).

22. Device according to one of claims 10 to 21, wherein the stamps (19, 27) of all workstations are arranged on a common stamp block.