EP1165264B1

EP1165264B1 - Tool holding fixture for bending brakes

Info

Publication number: EP1165264B1
Application number: EP00926785A
Authority: EP
Inventors: Gianluca Tarasconi
Original assignee: Toolspress Srl
Current assignee: Toolspress Srl
Priority date: 1999-04-07
Filing date: 2000-03-31
Publication date: 2003-05-21
Anticipated expiration: 2020-03-31
Also published as: ATE240798T1; IT1309745B1; ITRE990039A0; EP1165264A1; WO2000059655A1; AU4541300A; DE60002845T2; ES2195888T3; DE60002845D1; ITRE990039A1

Abstract

Fixture for fixing the tools to the upper and lower toolplate of sheet metal bending brakes, comprising a clamp fixed to the respective toolplate and having a lower channel for receiving the tool shank, which is provided with a groove along its entire length, means for supporting the shank in said channel while leaving it free to slide along the channel, and means for locking the shank in said channel, in one of the opposing walls of the channel there are provided; parallel to the channel axis and in correspondence with the groove in the tool shank, at least two aligned holes into which there is inserted freely slidable a movable body having a dimension greater than the wall thickness; means for maintaining said movable body elastically pressed into said groove in the tool shank; and first means counteracting said elastic means to annul their pressure against said groove.

Description

Technical field

This invention relates to bending brakes and more particularly to the means for retaining and locking the working utensils used by these brakes.

Background art

Bending brakes generally comprise a structure supporting two vertically-positioned substantially coplanar opposing toolplates, of which one can move vertically.
To the facing edges of the toolplates are fixed the means for retaining and locking the punch and die respectively, each of these being formed from a plurality of tools aligned in succession, they having the same shape but different lengths.
When the type of work changes, one or more tools have also to be changed, this being generally done by withdrawing or inserting the tools laterally in the direction of the edge of the metal sheet. Withdrawing, adding or changing a tool is a particularly delicate and even dangerous operation, in particular with regard to the upper tools, which can also be very long and heavy.
For this reason, fixtures have been developed for bending brakes which enable the tool to be withdrawn vertically, in the brake working direction.
These fixtures are rather complicated because they have to comprise safety means to prevent any accidental fall of the tool when it is released.
One of these fixtures is fully described in EP 0494714, in which the tool retention and locking means comprise a lower channel into which the upper portion of the tool, also known as the shank, is inserted.
The tool can be inserted from below into a seat having the same form as the shank, and locked in position by a plurality of pneumatically operated pistons which enter a longitudinal groove provided in the tool shank. Each tool also has a safety device comprising a lever for operating a peg movable within a hole in the tool shank. When the tool has been inserted into the seat in said retention and locking means, this peg is maintained elastically inserted in a longitudinal cavity in one of the vertical walls of said seat.
When a tool, for example one of those which form the upper punch of the brake, is to be changed, the locking pistons are retracted so that the tool is supported only by the peg.
At this point the tool can be withdrawn in the direction of the sheet edge, or by pressing said lever it can be withdrawn in the vertical direction.
This solution is costly to implement, and in addition the peg present in the safety device is easily damaged during use, so being unable to perform its safety function.
Another of these fixtures is fully described in EP-A-0256245, disclosing a fixture according to the preamble of claim 1.
This fixture has a very complicated structure located out of the body.
The object of the invention is to overcome the aforementioned drawbacks within the framework of a rational, reliable and low-cost solution.

Disclosure of the invention

The invention attains this and further objects by virtue of the characteristics defined in the claims.
To better clarify the constructional and operational characteristics of the invention a preferred embodiment thereof is described hereinafter by way of non-limiting example and is illustrated on the accompanying drawings.
Figure 1 is an isometric schematic view of the brake on which the device of the invention is mounted.
Figure 2 is an isometric view of the invention.
Figure 3 is a front view in the direction III of Figure 2.
Figure 4 is a section on the line IV-IV of Figure 3.
Figure 5 is a section on the line V-V of Figure 3.
Figure 6 is a section on the line VI-VI of Figure 3.
From the figures it can be seen that the bending brake 1 comprises a movable upper toolplate 2 and a fixed lower toolplate 3.
The upper toolplate 2 lowerly carries a series of aligned tools 4 having the same shape but different lengths, they forming overall the punch of the brake 1. Likewise the fixed lower toolplate 3 carries a series of aligned tools 5 forming the die of the brake 1. In detail, the tools 4 forming the punch and the tools 5 forming the die are secured to the respective toolplates 2 and 3 by a series of mutually contacting aligned clamps 6, as shown in Figures 1 and 2.
The clamps 6 are fixed to the respective upper and lower toolplates by usual means indicated by 7.
In the illustrated example, each clamp 6 has a length of 50 cm, and consists of a beam 61 having two successive recessed regions indicated by 610 and 611 respectively.
The recessed region 610 receives a plate 62 fixed to it by screws, not shown.
The plate 62 defines with the recessed region 611 a seat 63 for receiving the shanks 41 and 51 of the tools 4 and 5 respectively. The plate 62 comprises a succession of in-line holes 60 each arranged to receive two balls 64 occupying together a space longer than the thickness of the plate 62.
A push rod or pin could be conveniently used instead of the balls. In the shank of each tool 4 and 5, which is inserted into the channel 63, there are provided two opposing longitudinal grooves 40, both arranged to face the line of holes 60 to partly receive one of said two balls.
It should be noted that when the shank 41, 51 is inserted into the respective seat 63, the axis of the grooves 40 is slightly displaced from the axis of the holes 60, so that the pressure of the balls maintains the shank pressed into its seat.
On that side facing the plate 62, the beam 61 supports a series of leaf springs 9 fixed in a position inclined towards the beam by a line of bolts 91, and such that their lower portion elastically rests against the line of balls 64.
That portion facing the balls 64 is separated by cuts 92, between which individual independent elastic portions 93 of each leaf spring 9 are defined.
The beam 61 also comprises a line of holes 100 communicating with a common upper manifold 101 via ducts 102.
The holes 100 are dead, with their opening facing the plate 62.
A cup-shaped piston 103 with its axial dimension slightly less than the depth of the holes 100 is inserted into each hole 100.
In front of each hole 100, the plate 62 comprises a hole 65 receiving a pin 66 which at one end is received within the piston 103 and at the other end rests against the leaf spring 9.
On the opposite side to that supporting the leaf spring 9, the beam 61 has a central vertical recess 8 extending through its entire height.
Within said recess there is supported, parallel to the axis of the beam 61, a shaft 81 which carries two cams 82 close to its ends and is rigid with a central operating lever 83.
In front of each of the cams 82 both the beam 61 and the plate 62 have a through hole 84 receiving a pin 85 which rests against the central leaf spring 9.
Turning the operating lever causes the pin 85 to emerge and withdraw the spring through a distance greater than that resulting from operating the pistons 103.
The operation of the invention is apparent.
On feeding pressurized fluid to the pistons 103 the pressure of the leaf springs 9 on the balls 64 is released, so that the tool shank is free to slide within its seat to enable the tool to be withdrawn in a direction parallel to the axis of the beam 61.
The central tool lying in front of the central leaf spring 9 in contact with the pins 85 can also be withdrawn downwards by operating the lever 83, which moves the ball 64 completely into the hole 60.
The tools are inserted from the central position of each clamp 6, in the following manner.
Pressurized fluid is fed to all the pistons 103, to annul the pressure of the leaf springs 9 on the balls 64.
The lever 83 is then operated manually, and a first tool is inserted from below into its retention seat.
On returning the lever 83 to its initial position, the tool is prevented from falling downwards, but is not prevented from sliding within the retention seat, hence it can be slid away from the central portion of the beam, which is freed to receive the next tool, and so on.
Finally, it should be noted that this embodiment refers to a brake having a movable upper toolplate and a fixed lower toolplate. However in certain embodiments and for certain types of work the upper toolplate can be fixed and the lower toolplate movable, or both toolplates movable.

Claims

A fixture for fixing the tools (4,5) to the toolplate (2,3) of sheet metal bending brakes, comprising a clamp (6) having a channel (63) for receiving the tool shank, means (64) for supporting the shank in said channel while leaving it free to slide along the channel, and means for locking the shank in said channel, wherein in one of the opposing walls of the channel there are provided, parallel to the channel axis, at least two aligned holes (60) into which there is inserted freely slidable a movable body (64) having a dimension greater than the wall thickness of said one of the opposing walls, characterised by means consisting of a leaf spring (9) fixed onto the outside of the clamp for maintaining said movable body into said channel and first means (66) counteracting said elastic means (9) to annul their pressure against said movable body.
A fixture as claimed in claim 1, characterised in that said movable body consists of a pair of balls (64).
A fixture as claimed in claim 1, characterised in that the lower part of said leaf spring (9) is separated into portions (93) which deform independently of each other.
A fixture as claimed in claim 1, characterised in that said first counteracting means are a series of controlled-stroke fluid cylinder-piston units (103) acting on pins (66) which are slidingly located within holes in the wall of said channel and act on said leaf spring.
A fixture as claimed in claim 1, characterised in that in the centre of that wall opposite the wall on which the leaf spring is located, the clamp comprises, extending through its entire height, a recess in which there is located a shaft (81) which can be rotated by the action of a lever (83), to operate second means for counteracting said elastic means in order to set them in a completely inactive position.
A fixture as claimed in claim 5, characterised in that said second counteracting means comprise at least one cam (82) keyed onto said shaft (81) and acting on a pin (85) which is located within a corresponding through hole in the clamp wall and is in contact with the spring on the other side of the clamp.
A fixture as claimed in claims 1 and 6, characterised in that the contour of said cam (82) is such as to deform the spring outwards by an amount such as to enable the movable body (64) to retract into the respective hole.