GB2229126A - Cutting mechanism for bending machine - Google Patents

Description

-i CUTTING MECHANISM FOR BENDING MACHINE The invention relates to cutting

mechanism for bending machines, mainly for cutting cycle rims and similar bent profiles.

Various cutting mechanisms are known in the practice mainly for cutting circular profiles rolled from band steel, e.g. cycle rims, mudguards and similar objects bent with bending machine. Such is for example the Hungarian tilting shears known in the trade by the name: "RUGV-CSEPEL". It has a length gauge fitted with measuring wheel, axially turnable tilting arm mounted on the bending machine and provided with an additional driving mechanism. The tilting arm is provided with cutting and clamping device. End positions of the tilting arm and cutting arm are sensed by limit switches.

According to the experiences acquired in the practice, the slip due to production inaccuracy and meanwhile wear of the tilting arm's driving mechanism, inaccurate mechanical actuation of the limit switches, furthermore the incorrect clamping of the profile-band to be cut occurring mainly at high speeds - may result in series of serious faults to the detriment of quality. For this reason, tolerance of the profile's cutting length is unacceptably high, minimum 1 1.5 mm. But under certain unfavourable conditions it may be many times greater, which would not meet the require ments of up-to-date quality.

The present invention is aimed at elimination of above shortcomings, i.e. at the realization of an improved cutting mechanism ensuring considerably better dimensional cutting accuracy without the need of outside intervention, and the quality of the work is independent of the driving speed of the band-profile.

The initially described cutting mechanism was used as starting point to solve the problem. This has a tilting arm turnably arranged on the bending machine, and length gauge for the advanced profile to be cut, where the tilting arm is associated with remote controlled clamping-cutting unit.

The essence of the present invention lies in that the clamping-cutting unit consists of die, stamp and chuck displaceable with a drive, mainly working cylinder, in the sense of clamping, cutting and releasing the profile to be cut, the position of said clamping-cutting unit being preferably infinitely variable along the length of the tilting arm. Said tilting arm is turnable around the horizontal shaft with the aid of a further drive, mainly working cylinder. Said working cylinders of the cutting mechanism - independently of the bending machine - are in control connection with the length gauge coacting with the advanced profile to be cut.

The measuring wheel of the length gauge rolling on the profile is preferably associated with an electronic pulse-emitting counter connected to the central control unit of the working cylinders.

Furthermore, it is preferable to connect the stamp and chuck - through a common supporting longitudinal die-holder - with the hydraulic driving cylinder. In given case, elastic support is built between the chuck and the die-holder.

S In essence, the problem is solved according to the invention so that instead of actuating the tilting arm provided with cutting unit without the earlier described additional driving mechanism, it is turned with the advanced workpiece (profile to be cut) itself, which is preceeded by reliable, slip-free interlinking of the profile and cutting unit, as well as clamping of the workpiece. This way, the intermediate drive chain is eliminated, which adversely influences the cutting tolerance in the known solutions, furthermore a much simpler mechanism is realized, where the actuating cylinders are remote controlled directly from the length gauge, in other words, the operation becomes automatic.

The invention is described in detail by way of example, with the aid of the enclosed drawing, in which:

Fig. 1: schematic side view of the bending machine provided with the cutting mechanism according to the invention, Fig. 2: top view of the solution shown in Fig.L, Fig. 3: top view and partially sectional view of the cutting mechanism according to the invention, drawn to relatively larger scale.

A conventional bending machine 1 is shown in Fig. 1 and 2. This is described as absolutely necessary for the disclosure of a preferred embodi- ment of the cutting mechanism 2 according to the invention, arranged on the bending machine 1.

The illustrated bending machine 1 serves the purpose of bending a mudguard profile 3 made of band steel for bicycle. In the present ca5e, the 1 1 k_ 1 1 4 finished size of the profiles 3 to be cut was selected to 1992 mm.

The machinery is provided with a-length gauge 4 coacting with the profile 3 to be cut. Its purpose is to measure the feed length of the advanced profile 3. The length gauge 4 comprisis a measuring wheel 5 engaged slipfree (by friction drive) with the advanced profile 3. The measuring wheel 5 is fixed on a shaft 7 of an electronic counter 6. The electronic counter 6 emits electric pulses, which directly control the operation of the cutting mechanism 2 according to the invention, as described in detail hereinafter.

The bending machine 1 has roller-pairs 8 supporting the profile 3 to be cut on the top and underneath. Driving direction of the profile 3 is marked by arrow 9. Looking in this direction, a schematically illustrated bending roller 10 is arranged after the supporting roller-pairs 8, its position is adjustable according to the required bending radius.

Fig. 1 clearly shows that the cutting mechanism 2 according to the invention is connected through a horizontal shaft 11 with the bending machine 1.

A tilting arm 12 of the cutting mechanism 2 is turnable around the shaff 11. It is schematically illustrated in Fig. 1, that the horizontal shaft 11 is vertically displaceable in a link 13 with the aid of an adjusting spindle 14. This way, the cutting mechanism 2 is capable to conform to the different bending radii. (Minimal and maximal bending radii are shown by way of example in Fig. 1, marked with R1 and R2 respectively.) The turnable tilting arm 12 according to the 1 invention is provided with a clamping-cutting unit 15 suitable for the slip-free clamping of the profile 3 before and during cutting. In the case of embodiment shown by way of example in Fig. 3, the clamping-cutting unit 15 has a die 16, the recess of which is selected as to have the profile 3 resting in it along its whole outer surface. The clamping-cutting unit 15 is provided with a stamp 17 and a chuck 18 which are in coaction with the die 16. According to Fig. 3, the chuck 18 is supported elastically and relatively returnably through compression springs 19 by a die-holder 20 guided on both sides in horizontal guide ways 21 and 22. The die-holder 20 is in driving connection in this case with a driving cylinder 23, which can be a hydraulic working cylinder connected thorugh a central control unit (not shown) to a hydraulic supply unit 24 (FigL 1 and 2.).

Fig. 3 shows that the clamping-cutting unit 15 is mounted on the tilting arm 12 by the inner guide way 22 in such a way that its distance from the centreline of the shaft 11 is longitudinally adjustable in a longitudinal hole 25 of the tilting arm 12. This distance was marked with reference number 26 in the drawing and its value is adjustable according to the predetermined bending radius R of the profile 3. The adjusting facility in this case is realized with an adjusting spindle 27.

Tilted position of the tilting arm 12 is marked with thin dashed line in Fig. 1 and its upper, horizontal basic position, with continuous line. Articulated apling is between the tilting arm 12 and a tilting drive, which can be a working cylinder 28, which in this case is a pneumatic 1.

- 6 working cylinder. (Its supply unit is not shown, but it should be noted that it is connected likewise with the central control unit.) The tilted lower end-position of the tilting arm 12 is sensed in this case by limit switch 29, furthermore, the clamping and cutting positions of the die-holder 20 are sensed by another limit switch 30, wherein the switches 29, 30 are connected with the central control unit.

The illustrated embodiment of the invention functions as follows:

Prior to starting up the machinery, the length gauge 4 is set to the required cutting length and the vertical position of the shaft 11 embedding the tilting arm 12 as well as the position of the clampingcutting unit 15 with the spindles 14, 27 respectively. Next, the measuring wheel 5 of the length gauge 4 is placed on the profile 3 to be cut arriving as band, and this is followed by starting the production line according to specified feed rate.

In operation, the measuring wheel 5 rolls slip-free down the advanced profile 3 by way of friction coupling, meanwhile measuring its length. As soon as the set feed length is reached, the electronic counter 6 of the length gauge 4 emits electric signal to the central control unit. Upon the control signal, the hydraulic working cylinder 23 begins operating in the sense of pushing, i.e.

the die-holder 20 and the chuck 18 move together to the left (Fig. 3), consequently it clamps the profile 3 slip-free into the recess of die 16. Since this way, slip-free coupling was brought about and the profile 3 to be cut is fed at - 7 continuous rate, the tilting arm 12 tips down around the shaft 11 from its upper end-position shown in Fig. 1 to its lower end-position marked with dashed line. At this point, this tilting movement is not prevented by the pneumatic working cylinder 28. Still before reaching the lower endposition, the stamp 17 begins to function upon further pushing of the hydraulic working cylinder 23, while the chuck 18 keeps the profile 3 clamped continuously and slip-free, whereby the cutting takes place.

Upon completion of the cutting, and when the tilting arm 12 reaches the lower end-position, the limit switch 29 emits a signal, and the central control unit controls the pneumatic working cylinder 28 in the sense of drawing out. This way, the tilting arm 12 is returned to its initial horizontal position. At the same time, the hydraulic cylinder 23 receives control signal from the control unit, i.e. it is actuated in the sense of drawing back the piston, when the die-holder 20, stamp 17 and chuck 18 are returned to their right hand position (Fig. 3).

Thereafter, upon each further control signal of the length gauge 4, the cutting process is automatically and cyclically performed until the profile 3 fed in the form of band is used up.

One of the most important advantages of the solution according to the invention is that the cutting mechanism 2 functions independently of the production line and bending machine 1 and so the inaccuracies due to the traditional drive are completely eliminated. Further advantage is that operation of the cutting mechanism is independent i 2 4 8 - of the profile's 3 feed rate and thereby the faults due to the so far unavoidable dynamic loads are also eliminated. Furthermore, construction, handling and maintenance of the cutting mechanism 2 according to the invention are much simpler, and its operational safety is more reliable. In given case, the cutting mechanism 2 according to the invention independently of the profile-shaping production line, can be operated with the bending machine 1 alone, more accurately than with the known solutions.

In the annexed claims reference numbers have been used purely by way of example in order to facilitate comprehension, but it is hereby declare that absolutely no limitation of scope whatsoever is intended thereby.

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Claims (5)

1. Cutting mechanism for bending machine, mainly for cutting cycle rims and similar bent profiles, comprising a tilting arm displaceably arranged on the bending machine and a length gauge for the advanced profile to be cut, said tilting arm is associated with clamping-cutting unit, wherein the clamping-cutting unit (15) has a die (16) receiving the profile (3) and a chuck (18) driven in the sense of clamping or releasing the profile (3), as well as a stamp (17) for cutting the profile, said clamping-cutting unit (15) is provided with a die-holder (20) being connected to the stamp (17) and the chuck (18) and longitudinally driven on the tilting arm (12) mainly by a hydraulic working cylinder in such a way that the chuck (18) in retracted position of the die-holder (20) relatively retractably against compression spring (19), said tilting arm (12) is turnable arranged around a horizontal shaft (11) by a tilting drive, mainly pneumatic working cylinder (28), furthermore, limit switches (29, 30) sensing the end position of the tilting arm (12) and the advanced end position of the die holder (20) are connected with a central control unit being in direct control connection with the length gauge (4) independently of the bending machine (1).

2. Cutting mechanism according to claim 1, c h a r a c t e r i z e d in that a measuring wheel (5) of the length gauge (4) engaged slip-free with the profile (3) is associated with an electronic counter (6).

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3. Cutting mechanism according to claim 1 or 2, c h a r a c t e r i z e d in that the die-holder (20) is guided in longitudinal guide-ways (21, 22) on the tilting arm (12) and it is fixed to the 5 tilting arm (12) by one of the guide ways (22) - preferably in longitudinal direction infinitely adjustable with an adjusting spindle (27).

4. Cutting mechanism substantially as shown and described. in the accompanying drawings.

5. A bending machine including a cutting mechanism as claimed in any preceding claim.

0 Publiahed 1990atT]2eP&tentOffice.State House. 6671 High Holborn. LondonWC1R4TP. Further copiesmaybe obtainedfrom The Patent,Wice. EWes Branch, St Idary Cray. Or]bigwn, Kent BR5 3RD. Printed by MulUplex techniques ltd. St Mary Cray, Kent. Con. V87