EP1406752A1 - Holding arrangement for punching tool insert - Google Patents

Abstract

A holding arrangement for attaching a tool insert to a holder with the aid of a ball which is movably held in an obliquely disposed conduit; the width of a conduit opening at the recess opening being less than the ball diameter. In the locked position, the ball, under the influence of a compression spring, is located in an identation in an outer face of the tool insert. To enable initiating such locking even in thin holders, the upper opening of the conduit is covered by a holding element which forms an abutment for the compression spring. As a result, threr is a considerable gain in spring travel, which makes it possible to use this holding arrangement even in thin holders.

Description

HOLDING ARRANGEMENT FOR PUNCHING TOOL INSERT

FIELD OF THE INVENTION

[0001] The invention relates to a holding arrangement for securing a

punching tool insert in a recess opening of a holder with the aid of a ball, the

ball being movably held in a conduit that extends obliquely to the recess

opening and which opens into the recess opening, the width of the conduit

opening at the recess opening being less than the ball diameter, and in the

locked position the ball rests, under the influence of a compression spring, in

an indentation in an outer face of the punching tool insert.

BACKGROUND OF THE INVENTION

[0002] As an example, one such holding arrangement is known by the

name "ball-lock" and is used among other purposes in punching/embossing

machines for large-scale mass production with a fixed tool arrangement. In

this application, the known holding arrangements have the purpose of

enabling rapid replacement of the tool insert, if the wear limit is reached or in

the event of failure, without having to remove the holder from the machine.

[0003] Fundamental advantages of the above-described holding

arrangement are the simple fastening of the tool insert in the holder, the

secure hold against falling out that is achieved by self-locking, very good rotary angle adjustment and securing of the tool insert relative to the holder

during the snap-in operation.

[0004] In the known versions, to hold the tool insert, the spring is

deflected inward as a unit over a plurality of thread courses mounted on the

conduit wall. This makes it difficult to adapt the holding arrangement to

other holders with a lesser depth, since a certain minimum spring travel

must be available in order, on the one hand to provide secure locking of the

tool insert and on the other hand to push the ball back to a position that

completely uncovers the tool insert so that it can be removed. Nor can the

spring travel be lengthened by increasing the inclination of the conduit

relative to the recess opening, because then the self-locking action for

securing the punching tool insert may under some circumstances no longer

exist.

SUMMARY OF THE INVENTION

[0005] An object of the present invention is to create a holding

arrangement, which has a ball as the locking member and which can be

used even with thin holders.

[0006] According to the invention, this object is attained in that in a

holding arrangement of the present type, the upper opening of the conduit in

the holder is covered by a holding element which forms an abutment for the

compression spring. [0007] With this arrangement, the spring need not be compressed

over a certain length as a unit and secured to the conduit wall, so that

compared to the known variants, considerable spring travel gains are

achieved, which make it possible to use the holding arrangement in thinner

holders. As a rule, it is not a problem to provide the holding element at a

certain point on the top of the holder and optionally to remachine the

receptacle for the holder in the machine tool.

[0008] This remachining of the receptacle can be omitted in a

particularly preferred embodiment of the invention, in which the holding

element is embodied as a key which is seated in a groove in the holder and

with which the holder can be fixed in a defined way in the correct angular

position in the receptacle of a punching machine. In many known holders,

such as holders made by the Trumpf system, a key is provided on the top

side of a calibration ring. In a holding arrangement of the invention this key

is given the further function of forming an abutment for the compression

spring. The groove for the key and the conduit for guiding the ball are

fabricated in a vise, so that with the aid of the key and the holding

arrangement of the invention, a defined angular position of the tool insert

relative to the receptacle for the holder in the machine tool simultaneously

exists without further action being taken.

[0009] As a further preferred provision to increase the spring travel, in

a holder in accordance with or similar to the Trumpf system, the calibration ring is thicker than in normal holders, and the projection distance of the

punching tool out of the holder is correspondingly less.

[0010] In the usual holders regrinding of the formed-on punching tool

is possible in order to lower tool costs. In this case a considerable

projection distance of the tool out of the holder is unavoidable. In contrast,

the holding arrangement of the present invention allows the use of

disposable tools in a re-usable holder, so that a considerable reduction in

cost can be achieved compared to the holders previously made in one-piece

with the punching tool, and remachining of the punching tool insert can be

omitted. The punching tool insert is preferably provided with a coating that

increases its service life, such as TiN. In the punching tool insert in the form

of a disposable element, the coating can develop its full effect, since while a

coating is also possible in the known holders, the requisite regrinding of the

tool means that the optimal effect is achieved only in new tools.

[0011] In this connection, it is also a cost advantage that the costs for

a coating do not depend on the area to be coated but rather on the volume

of the workpiece, so that the small punching tool inserts can be coated in the

region of the tool blade at substantially more favorable cost than integral

holders with a formed-on tool.

[0012] In a further preferred embodiment of the invention, the shaft

end of the punching tool insert behind the indentation, which for instance is

a convex elongated rounded indentation, is shortened. The reduction in the length of the shaft end is available especially in very thin holders, in order to

enable an introduction of force into the holder from the end face of the

punching tool insert. By comparison, if recess openings are too deep,

excessive weakening of the remaining material could occur.

[0013] In very thin holders, it can be expedient to provide a holding

arrangement in which the indentation is adjoined by a groove which extends

as far as the end of the shaft and is shallower and narrower than the

indentation. This groove can make it possible to remove the tool insert from

the recess opening even if the ball cannot be pushed all the way back into

the conduit, for instance because it was not possible to achieve an adequate

length of spring travel. It is understood that the groove must be embodied

as correspondingly shallow and narrow, so that the hold of the tool insert in

the holder to prevent it from falling out is assured under all circumstances,

even under the tensile forces that occur in operation.

[0014] To make it possible to move the ball out of the locked position

into a released position, in which the punching tool insert can be removed,

openings or bores, for instance parallel or vertical to the recess opening, can

be provided, through which bore a pin or the like can be introduced to press

the ball back, counter to the force of the compression spring, into a position

that uncovers the punching tool insert. [0015] In a vertical arrangement an oblong slot is preferred, so that

with the pin, using leverage, the ball can be moved into its unlocked

position.

[0016] A further advantageous provision for making the process of

disassembling the punching tool insert easier can be that the holder has a

through bore which opens into the recess opening approximately centrally in

the end face. By introducing an expulsion tool into this through bore, even

solidly fixed punching tool inserts can easily be removed from the recess

opening once the ball has been released.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] An exemplary embodiment of the invention will be described in

detail below in conjunction with the accompanying drawings, wherein:

[0018] Fig. 1 is a cross sectional view through a holder without a

punching tool insert;

[0019] Fig. 2 is a side view of the holder of Fig. 1 ;

[0020] Fig. 3 shows a detail of the tool of Fig. 2;

[0021] Fig. 4 is a side elevational view of a punching tool insert;

[0022] Fig. 5 is a partial cross-sectional view taken along line 5-5 of

Fig. 4; and

[0023] Fig. 6 is a cross sectional view through a device for expelling a

punching tool insert from the holder of Fig. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Fig. 1 shows a holder 10 for a punching tool insert (an example

of which is shown in Figs. 4 and 5), which, as in the Trumpf system

comprises a suitable shaft 14 and a calibration ring 16 so that it can be

received in a punching machine. The calibration ring 16, which as will be

described in further detail hereinafter, is thicker, compared to the usual tools

of the Trumpf system wherein the holder and the tool insert are made in one

piece. The calibration ring 16 is provided with a recess opening 18, into

which the punching tool insert can be introduced with the end face of the

tool insert resting on a bearing face 20 to transmit the punching forces to the

holder.

[0025] A key 22 is secured in a groove 24 on the top of the calibration

ring with the aid of a screw 26, which fixes the angular position of the holder

10 in the punching machine. At the same time, the inner end of the key

covers an upper opening of a conduit 28, which is inclined at an angle α,

which may be about 15°, in the calibration ring 16, such that this conduit

opens at 30 into the recess opening 18. The width of the opening 30 into

the recess opening 18 is less than the full width of the conduit 28. As a

result, a ball 32 movably guided in the conduit 28 is prevented from falling

out into the recess opening 18. The ball 32 is urged into the position shown

in Fig. 1 by a prestressed compression spring disposed in the conduit 28. In

this position, the ball 32 protrudes with part of its circumference into the recess opening 18. The key 22 forms the abutment for the compression

spring, which may be a helical spring, as shown at 42.

[0026] In the punching tool insert inserted in the recess opening 18,

the ball 32 rests in an elongated rounded convex indentation in the surface

of the tool insert. In conjunction with an inclination β of about 11° in the wall

of the indentation, a self-locking effect ensues, which prevents the tool insert

from falling out of the recess opening 18, even under the tensile forces

occurring in operation. At the same time, the ball 32 assures angular

alignment of the punching tool insert, so that in conjunction with the key 22,

a defined position of the tool insert relative to the receptacle of the punching

machine is obtained. To avoid production variations, it is expedient for the

groove 24 for retaining the key 22 in the calibration ring 16 and the conduit

28 for receiving the ball 32 to be held in a vise.

[0027] A suitable tool insert 43 is shown in Figs. 4 and 5. This tool

insert 43 is relatively short in length, for reasons described above. It

includes a shaft 44 and an end face 45 which abuts bearing face 20 of

recess opening 18. An indentation 46 for receiving the ball 32 in the locked

position is curved in cross section and its walls extend downwardly at an

angle β to the vertical of approximately 11 °. An 11 ° angle of indentation 46,

coupled with the 15° inclination of conduit 28 assures locking of the ball 32

in indentation 46. For easing insertion of tool insert 43 into recess opening

18, the tool insert includes a tapered portion 47 in the form of a conical guide extending downwardly from the shaft end 45. This conical guide 47

joins with indentation 46 at transition point 48 which, lying essentially on the

circumference of shaft 44, can be felt as the shaft is pushed in and the bail

32 rides over it and snaps into its locking position in indentation 46.

[0028] Using the alignment key 22 as an abutment for the

compression spring 42 disposed in the conduit 28 makes an adequate

spring travel possible, even though, in comparison to similar holding devices

calibration ring 16 is very thin. With this arrangement, the ball 32 can be

moved back into a position in which the punching tool insert can be removed

from the recess opening 18 without difficulty. A through bore 34 in the shaft

14 of the holder 10 optionally allows the introduction of an expulsion pin, for

forcing out a tool insert that has become jammed. (See Fig. 6.)

[0029] To move the ball 32 out of its locking position into a released

position counter to the load of the compression spring, a first opening,

aligned parallel with the recess opening 18, is provided in the form of a bore

36, through which a pin can be introduced to force the ball 32 back up the

conduit 28.

[0030] To enable moving the ball 32 into the released position when

tool inserts in which the blade distances are greater than the diameter of the

recess opening 18 to be used as well, a further, second opening 38 is

provided, disposed transversely to the recess opening 18 and the bore 36.

This second opening is in the form of an oblong slot 38, the width of which is narrower than the diameter of the ball 32, so as not to hinder the motion of

the ball 32 in the conduit 28. By introducing a pin 40 (see Fig. 3), the ball

can be lifted into the released position shown in Fig. 3, and optionally the

outer edge of the oblong slot 38 can be used as a bearing surface for the

pin 40 in order to achieve leverage (see also Fig. 6).

[0031] The punching tool insert used with the present invention, an

example of which is shown in Figs. 4 and 5, has a shorter shaft than the

inserts used in comparable, previously known holding arrangements. This is

because otherwise, i.e., if the shaft were longer, the transitional region

between the shaft 14 and the calibration ring 16 would be weakened too

much to allow the forces occurring in punching to be reliably transferred to

the punching machine. In comparison with the known holders that have a

formed-on tool, the projection distance of the punching tool insert out of the

recess opening 18 is reduced to the extent by which the calibration ring 16 is

made thicker. Since the punching tool insert is intended as a disposable

tool without regrinding, this reduced length is not significant.

[0032] Fig. 6 shows the removal of the punching tool insert from the

holder 10 with the aid of a changing device 50. The changing device 50 has

a receptacle 52, which in terms of geometry is made similar to the

receptacle of a punching machine, with a resilient locking bolt element 54

that engages the recess 55 provided in the shaft 14 of the holder 0 to fix

the holder 10 on the device 50. A lever 56 of the changing device 50 acts on a linearly guided expulsion element 58, which has a pin 60 that protrudes

through the through bore 34 as far as the inside of the recess opening 18

and that by actuation of the lever 56 can expel the punching tool insert.

First, however, it is necessary for the pin 40 to be introduced through the

oblong slot 38, and by pivoting about the pivot point described above for the

ball 32 to be moved into its retracted position, in which the punching tool

insert is removable. In tool inserts with a small blade diameter, it is also

possible to introduce the pin 40 through the opening 36 from the underside

of the calibration ring 16, in order to unlock the ball 32 before the tool insert

is forced out of the recess opening 18 with the aid of the lever 56.

[0033] The introduction of a new tool insert is done by simply pressing

it in. The tool insert first forces the ball 32 backward until the ball can snap

into the indentation provided.

[0034] Although the invention has been described in detail with

respect to preferred embodiments, it will be apparent that the invention is

capable of numerous variations and modifications, apparent to those of

ordinary skill in the art.

Claims

Claims

1. A holding arrangement for attaching a tool insert to a holder

with the aid of a ball held movably in a conduit that extends obliquely to a

recess opening in the holder, and which conduit opens into the recess

opening, the width of the conduit opening toward the recess opening being

less than the ball diameter, and wherein, in the locked position the ball rests,

under the influence of a compression spring, in an indentation in an outer

face of the tool insert, the upper opening of the conduit in the holder being

covered by a holding element which forms an abutment for the compression

spring.

2. The invention of claim 1 , wherein the holding element is a key

which is seated in a groove in the holder and with which the holder can be

fixed in a defined angular position in a receptacle of a punching machine.

3. The invention of claim 1 , wherein the indentation is elongated,

rounded and convex, the shaft end of the tool insert above the indentation

being shortened.

4. The invention of claim 1 , wherein the indentation is adjoined by

a groove which extends as far as the end of the shaft and is shallower and

narrower than the indentation.

5. The invention of claim 1 , including a bore located essentially

parallel to the recess opening for releasing the tool insert through which

bore a pin can be introduced to press the ball back, counter to the force of

the compression spring, into a position that releases the tool insert.

6. The invention of claim 1 , including an unlocking opening,

extending essentially perpendicular to the recess opening through which

bore a pin can be introduced to press the ball, counter to the force of the

compression spring, into a position that releases the punching tool insert.

7. The invention of claim 6, wherein the unlocking opening is in

the shape of an oblong slot, and the width of the opening is less than the

ball diameter.

8. The invention of claim 1 , wherein the holder has a through

bore, which opens into the recess opening approximately centrally in the

end face of the tool insert.

9. The invention of claim 1 , wherein the holder has a calibration

ring which includes the conduit, and the thickness of the calibration ring is

increased and the amount of projection of the punching tool out of the holder

is reduced by the same extent.

10. The invention of claim 1 , wherein the tool insert is provided

with a coating that increases the longevity of the tool insert.

11. The invention of claim 10, wherein the coating is TiN.