GB2461114A

GB2461114A - Punching Apparatus with temperature control means

Info

Publication number: GB2461114A
Application number: GB0803924A
Authority: GB
Inventors: Giorgio Ostini
Original assignee: Tradewise Engineering Ltd; Euromac SpA
Current assignee: Tradewise Engineering Ltd; Euromac SpA
Priority date: 2008-03-01
Filing date: 2008-03-01
Publication date: 2009-12-30
Also published as: EP2259916A1; GB0803924D0; WO2009109882A1

Abstract

Punching apparatus comprising: first housing means (9,9A)in which punching means can be arranged that can be driven by driving means (7, 8) and having a first temperature (T1); second housing means (10, 12) in which die means (11) can be arranged, positioned aligned with said punching means, having a second temperature (T2), heat adjustment means (14A, 14B; 15) being provided to make/maintain said first temperature (T1) and second temperature (T2) substantially the same.

Description

"PUNCHING APPARATUS".

TECHNICAL FIELD OF THE INVENTION.

The invention relates to a punching apparatus, suitable for being fitted on punching machines for working pieces in the shape of sheets, bars, profiles and the like made of metal or plastic material.

TECHNOLOGICAL BACKGROUND.

For some time now punching machines have been known and used that comprise a punching head, a support surface for the pieces to be punched, located underneath the punching head and a supporting base for both the support surface and the punching head.

In the latter a presser cylinder is housed that can be driven with a fluid, normally oil, that works by pressing on one or more punches arranged in a special housing seat, inside a suitable punch-holder, obtained in the punching head underneath this presser cylinder.

Vertically on the presser cylinder and the punch-holder, a housing seat is obtained in the support surface for housing female dies designed to internally receive the tips of the punches during the punching phase.

This arrangement of the punches and the dies calls for the vertical alignment between these to be very precise, i.e. coaxial, to prevent any misalignment damaging the punches due to an imperfect coupling with the respective dies during their punching stroke.

Normally, both the punching head and the support surface of the materials to be punched are made in a one piece that forms the body of the punching machine.

The prior state of the art has the following drawback: when a piece is punched, the oil that drives the presser cylinder heats up a lot due to the increase in pressure it has to withstand.

This heating is transmitted by heat conduction to the punching head body, causing the latter to dilate.

This dilation causes outward movement, mainly towards the front of the punching machine, of the seat in which the punch-holder is housed, with respect to the set obtained in the support surface in which the dies are housed.

This movement, which has been ascertained to be around one hundredth of a millimetre for every degree of thermal difference, called "itt", between the punching head and the support surface, determines a misalignment between the punches and the respective dies, which is proportionately greater when the pieces to be punched have reduced thicknesses.

As has been said, this misalignment gradually damages th tips of the punches and also the outlines of the dies, because the punches penetrate the latter in a forced way due to reciprocal misalignment.

This requires the periodical and frequent replacement of both the punches arid the dies, producing an increase in piece punching costs.

OBJECTS OF THE INVENTION.

One object of the invention is to upgrade the state

of the prior art.

Another object of the invention is to make a punching apparatus that allows maintaining the punches and the dies aligned in the punching machines, during all the operating phases of the latter, in particular also during the punching phase, when the fluid that drives the presser cylinder heats up and, consequently, the punching head dilates.

According to a first aspect of the invention, a punching apparatus is provided comprising: first housing means in which punching means can be arranged that can be driven by driving means and having a first temperature; second housing means in which die means can be arranged, positioned aligned with said punching means, having a second temperature, characterized in that heat adjustment means are provided to make/maintain said first temperature and second temperature substantially the same.

According to a second aspect of the invention, a method is provided for adjusting heat dilations in punching apparatus comprising: first housing means for housing punching means; second housing means for housing die means placed aligned with said punching means, characterized in that it comprises adjusting/maintaining a first temperature of said first housing means and a second temperature of said second housing means substantially the same at least -during punching operations, in such.a way that said first housing means and second housing means have dilations substantially similar in terms of value and direction.

BRIEF DESCRIPTION OF THE DRAWINGS.

Further characteristics and advantages of the invention will appear more evident from the detailed description of a punching apparatus and a method for adjusting heat dilations in punching apparatus, illustrated indicatively by way of non limiting example, in the attached drawings wherein: Figure 1 is a side schematic view and on a reduced scale of a punching machine having the punching apparatus according to the invention; Figure 2 is a very schematic front view of a punching area of the punching machine of Figure 1; Figure 3 is a very schematic front view of a second version of a punching area of a punching apparatus according to the invention; Figure 4 is a side schematic view and on a reduced scale of a punching machine having the punching apparatus according of Figure 3.

EMBODIMENTS OF THE INVENTION.

With reference to the Figure 1, by 1 is generally indicated a punching machine, which comprises a frame 2 that is made up of a head 3 and of a base 4, having a worktable 5 on which pieces to be punched can be rested.

The inside of the head 3 houses an upper part of a punching apparatus, generally indicated by 6, while a lower part of this is housed in the worktable 5, in such a way as to be vertically aligned with the upper part.

In detail, the upper part schematically comprises a presser cylinder 7 which is driven up and down by means of a hydraulic supply unit 8 which, during punching operations, sends the presser cylinder 7 an adequate volume of oil under pressure.

The presser cylinder 7 is arranged above a first housing 9, normally having the possibility of turning, inside which one or more punches can be arranged to perform the punching operations and which is supported on the punching machine by means of a support 9A.

The punches, both single and multiple, even though not visible in the drawings, are nofmally positioned inide respective punch-holders, which in turn are housed in specific seats arranged inside the first housing 9.

Similarly, the lower part of the punching apparatus comprises a second housing 10, this too having the possibility of turning, in which dies 11 are arranged, in such a way that they are vertically aligned with the respective punches arranged in the first housing 9.

It is well known that a perfect vertical alignment between the dies 11 and the respective punches is crucial for preventing, in the case of undesired misalignment occurring, of even only a few hundredths of a millimetre, when the punches penetrate the dies during the punching operations, damage occurring to both, or else irregular wear, which implies the very frequent replacement and grinding of both.

The second housing 10 is supported by a base 12 which is associated with the frame 2 of the punching machine 1 in a conventional way.

In the preferred embodiment of the punching apparatus 6, the supply unit 8 is hydraulically connected to this by means of a delivery pipe 13 and a backflow pipe 14.

The supply unit 8 comprises a tank 8A for containing the oil and a pumping unit 8B to pump it to the presser cylinder 7.

From the backflow pipe 14 a section 14A is derived of a further pipe that connects it to the base 12; from the latter departs a further section 14B of backflow pipe that empties into the tank 8A.

As can be seen from the Figure 2, the two sections of pipe 14A and 14B are connected together and in the connection area, at the base 12, are shaped so as to cross it or wrap around a considerable portion of it.

With the broken lines 9' and 10' have been indicated in the Figure 1, in an intentionally amplified way with respect to reality, for better understanding, the positions of the first housing 9 and of the second housing 10 respectively during one punching phase, during which, because of the heating of the latter, the dilation of both occurs in the same direction and to substantially the same value, thus maintaining the alignment between the first housing 9 and the second housing 10 and, consequently, also between the punches and the respective dies 11.

The heating of the presser cylinder 7 and of the support 9A occurs spontaneously and is determined by the increase in temperature of the oil inside the presser cylinder 7, due to the increase in pressure to perform a punching operation: this heating determines an increase in temperature which is transmitted to the support 9A and to the head 3 by conduction, until a first temperature Ti is reached.

The base 12 is at a second temperature T2, which is lo%.rer than the temperature Ti, but, during the punching phases, it is heated, according to a first possible embodiment of the punching apparatus 1, by the same oil overheated during the compression phase which is contained in the presser cylinder 7 and which returns overheated towards the tank 8A.

A part of this oil is deviated towards the further delivery pipe section 14A, by means of a valve 16.

This overheated oil licks the base 12 of this, which, du to the induced heating, also dilates in the same direction as the dilation of the support 9A, and, therefore, of the upper housing 9 and to a value substantially the same as this, also moving with it the second lower housing 10.

The oil used to heat the base 12 is then made to return to the tank 8A through the further backflow pipe section 14B.

The circulation of the oil in the delivery pipe 13, baÃ�kflow pipe 14 and in the further delivery section 14A and backflow section 143 is produced by the operation of the pumping unit SB.

According to a further and possible embodiment of the invention shown in the Figures 3 and 4, it is also possible to have, in the base 12, or around this, an apparatus fitted with heating elements 15 and in this case, both the further sections of pipe 14A and 14B are eliminated because they are superfluous.

According to another alternative embodiment of the punching apparatus 1, instead of heating the base 12, it is possible to prevent the heat dilation of the support 9A of the first housing 9, by cooling it.

For this purpose, a cooling device can be fitted at this support 9A, such as, for example, a heat exchanger or an apparatus for blowing cold air on the support 9A, in such a way that, even if the oil inside the presser cylinder 7 heats up during the pressure increase due to punching, non-significant teriperature increases are induced on the support 9A of the first housing 9 or, in any case, in the head 3, such as to determine its dilation.

The operation of the punching apparatus 6 is the following: when a piece has to be punched, e.g. a metal sheet, it is arranged between the first upper housing 9 and the second lower housing 10, by means of gripper devices with which the punching machine is equipped and which move on the worktable 5.

When the piece is correctly positioned, the punching operation starts that calls for an increase in the pressure of the oil inside the supply unit 8, to start the presser cylinder 7, in such a way that this moves towards the first upper housing 9, inside which the punches to be used are placed.

The increase in pressure causes the consequent overheating of the oil inside the presser cylinder 7, bringing this to a temperature Tl which is transmitted by conduction also to the head 3 and to the support 9A of the first upper housing 9.

This increase in temperature causes a gradual dilation of the support 9A and of the head 3 which causes the first housing 9 to move by a few hundredths of a millimetre and this moves to position 9' The second lower housing 10 and the base 12 of this, at the start of the punching operation, are at a nomai temperature T2, lower than the temperature Ti.

Nevertheless, during the punching operation, the base 12, or directly the second housing 10 are heated to raise the normal temperature T2 until the same temperature Ti is substantially reached.

Once this heating has been completed, the base 12 or the second housing 10 consequently undergo the same substantial dilation of a few hundredths of a millimetre, until they reach the position 10' This second dilation therefore makes it possible to substantially maintain unchanged the alignment between the punches and the respective dies ii, preventing the occurrence of any misaligned couplings of these.

The heating of the base 12 and/or of the second lower housing 10 can occur, according to a first possible embodiment of the punching apparatus, by taking volumes of overheated oil from the supply unit 8 and conveying these to lick the base 12 and/or the second housing 10 by means of the further section of delivery pipe 14A.

More precisely, the valve 16, which is normally closed, but which opens on command in a controlled way, deviates, when open, a part of the oil flow overheated at the temperature Ti towards the section of pipe 14A and this returns from the presser cylinder 7 towards the tank 8A.

In the case illustrated, this part of the oil flow reaches the base 12, which is at the normal temperature T2 and, by conduction, heats it until it substantially reaches the temperature Ti, creating the previously-described dilation.

For a skilled person, imagining to arrange the section of pipe 14A in such a way that it also, or only, licks the second housing 10 is purely intuitive.

According to a further embodiment of the punching apparatus, it is also possible to have, in replacement of the sections of pipe 14A and l4B and of the pump 16, the fitting of heating wire resistances 15 inside the base 12, or arranged around this, in such a way that it is heated to the temperature Ti.

According to a further embodiment, it is also possible to prevent the heating of the head 3 and of the support 9A of the first upper housing 9, and, consequently, the dilation of these, keeping them cooled by means of a known cooling device, such as, for example, a cold-air blowing apparatus that invests both the head 3 and the support 9A.

This way as well, the alignment is maintained between the first upper housing 9 and the second lower housing 10 and, consequently, between the punches and the corresponding respective dies.

Claims

CLAIMS1. Punching apparatus comprising: -first housing means (9, 9A) in which punching means can be arranged that can be driven by driving means (7, 8) and having a first temperature (Ti); -second housing means (10, 12) in which die means (11) can be arranged positioned aligned with said punching means, having a second temperature (T2), characterized in that heat adjustment means (14A, 14B; 15) are provided to make/maintain said first temperature (Ti) and second temperature (T2) substantially the same.
2. Apparatus according to claim 1, wherein said heat adjustment means (14A, 14B; 15) can be started at least during punching operations.
3. Apparatus according to claims 1 and 2, wherein said first temperature (Ti) is transmitted to said first housing means (9, 9A) by said driving means (7, 8) during said punching operations.
4. Apparatus according to any of the claims from 1 to 3, wherein said first temperature (Ti) is higher than said second temperature (T2) .
5. Apparatus according to claim 1 or 4, wherein said heat adjustment means comprise heating means (14A, 14B; 15) to increase said second temperature (T2) up to said first temperature (Ti).
6. Apparatus according to claim 1 or 4, wherein said heat adjustment means comprise cooling means to lower said first temperature (Ti) to said second temperature (T2)
7. Apparatus according to any of the claims 1, 4, 5, wherein said heating means comprise a fluid dynamic connection circuit (13, 14, 14A, 14B) for connecting said first driving means (7, 8) and said second housing means (10, 12), in such a way as to convey a fluid having said first temperature (Ti) towards said second housing means (10, 12)
8. Apparatus according to claim 7, wherein said fluid dynamic circuit (13, 14, 14A, 14B) is arranged in such a way as to lick said second housing means (10, 12).
9. Apparatus according to claim 7, wherein said fluid dynamic circuit comprises a delivery path (14A) from said driving means (7, 8) to said second housing (10, 12) and a backflow path (14B).
10.Apparatus according to any of the claims 1, 4, 5, wherein said heating means comprise electric resistances (15) arranged inside said second housing means (10, 12)
11. Method for adjusting heat dilations in punching apparatus (6) comprising: first housing means (9, 9A) for housing punching means; second housing means (10, 12) for housing die means (11) placed aligned with said punching means, characterized in that it comprises adjusting/maintaining a first temperature (Ti) of said first housing means (9, 9A) and a second temperature (T2) of said second housing means (10, 12) substantially the same at least during punching operations, in such a way that said first housing means (9, 9A) and second housing * means (10, 12) have dilations (9', 10') substantially similar in terms of value and direction.
12.Method according to claim 11, wherein said first temperature comprises substantially an operating temperature (Ti) for operating fluid means (8, BA, 8B) for driving said punching means.
13.Method according to claim 12, wherein said fluid driving means (8, 8A, 8B) comprise a presser cylinder (7) operating on said punching means.
14.Method according to claim 11 or 12, wherein, in an initial punching phase, said first operating temperature (Ti) is higher than said second temperature (T2)
15.Method according to claim 11 wherein said maintaining/adjusting comprises maintaining/adjusting with heat adjustment means (14A, 14B; 15).
16.Method according to claim 14 or 15, wherein said heat adjustment means comprise a fluid dynamic connection circuit (13, 14, 14A, 143) for connecting in a fluid dynamic way said fluid driving means (7, 8, 8A, 8B) with said second housing means (10, 12)
17.Method according to claim 14 or 15, wherein said heat adjustment means comprise heating means (14A, 14B; 15) operating on at least said second housing means (10, 12), in such a way as to increase said second temperature (T2)
18.Nethod according to claim 14 or 15 wherein said heat adjustment means (14A, 14B; 15) comprise cooling means operating on at least said first * housing means (9, 9A), in such a way as to reduce said first operating temperature (Ti) substantially to said second temperature (T2)
19. Punching apparatus, substantially in accordance with any example hereinbefore described with reference to the accompanying drawings.
20. A method for adjusting heat dilations in punching apparatus, substantially in accordance with any example hereinbefore described with reference to the accompanying drawings.