JP5384356B2 - Punch stripper - Google Patents

Abstract

A punch stripper is adapted to be fastened to a punch retainer of a press tool, and to retain a work piece as the piece is being machined by a punch. The punch stripper includes a punch stripper piston and a pressure chamber adapted to spring-load the punch stripper piston. The pressure chamber is at least partially defined by a gap between an inner sleeve and an outer sleeve. The punch stripper piston has a portion that is axially displaceable in the gap.

Description

  The present invention relates to a punch stripper and a punching tool including the punch stripper. More particularly, the present invention relates to a punch stripper adapted to be fastened to a punch retainer, which may also be mounted on the movable upper tool portion of the press.

  In the sheet metal forming industry, punching tools are used to drill holes in metal sheets. The punching tool is mainly composed of a retainer, a punch and a stripper. The punching tool operates as a closure unit and is often mounted directly on the press tool on which the metal sheet is formed, but may be mounted on a shuttle that operates on a press tool that drills holes in different directions.

  The purpose of the punch is to make a hole in the metal sheet. The punches used have different sizes and shapes. Punches are a subject of standardization because they are frequently used. The same applies to punch retainers used for punching. The punch is mounted on a punch retainer and held in place through mechanical locking.

  The retainer itself is attached to the press tool. In the punching operation, the punching tool is located at the upper tool, and joins with the stationary punching die located at the lower tool portion by the downward movement. During the downward movement, the stripper joins the metal sheet and contacts the metal sheet. The punch continues its movement towards the sheet and is punched through the metal sheet. The primary purpose of the stripper is to hold the metal sheet in place during the punching operation, both during the down movement and during the return movement. Another purpose of the stripper is to support the punch during the punching operation. A large stripping force is required so that the stripper can pull back the punch after the punching operation without damaging the drilled hole.

  The stripping force can be generated by using an elastic part, such as a mechanical spring or an elastically deformable polyurethane element, the elastic part being biased with respect to the stripper part. The magnitude of the force is determined by the size of the elastic part being utilized and the spring constant. If the punching operation is performed without a stripper or with a stripping force that is too small, the metal sheet tends to follow the punch movement due to friction, so the metal sheet around the drilled hole will move back. There is a risk of being deformed inside.

  Within the sheet metal forming industry, demands that lead to higher production rates are constantly increasing. The result of this increased production rate is a faster press progression at higher press speeds and shorter idle times during the press cycle in order to maintain a high level of efficiency. In addition, longer production processes (not abnormal up to 2 million) result in increased press tool operating time, which is also the same for press tools and presses used in today's sheet metal forming industry. This means that more stringent requests will be made for both types. Existing presses are designed for significantly higher speeds than those used in the industry 20 years ago. Faster press progression also results in greater wear of the press, press tool and press tool components, which means that maintenance needs must be monitored.

As the production rate increases, the punching tool requirements also become more stringent to meet the increasing production rate and minimize maintenance.
The latest trend in the automotive industry is for expanded use of high-strength sheet metal. By optimizing each individual component of the vehicle for its intended function, it is possible to reduce weight and environmental impact. This trend in the automotive industry also affects the standardization of punching tools, taking into account that holes should be drilled in such areas.

  There are two types of punch strippers in the existing market. The first type is a built-in mechanical spring and the second type is a polyurethane element adapted to generate a stripping force. Both variants have problems and limitations.

  A punch stripper with a mechanical spring is actuated by a mechanical spring, the inner diameter of which is concentric with the outer diameter of the punch body and is mounted between the stripper part and the end part, and thus in the unit Apply pressure. The stripper portion has two outer diameters, one is the point of punching and one is the end of the spring. Both surfaces guide the stripper part during its working stroke. The stripper portion has a flat machined surface to prevent it from rotating. The punch stripper is designed as an integrated unit and can be replaced in connection with maintenance. If a larger or smaller stripping force is desired, the spring is replaced. Because needs vary, there are many different springs to choose from. In addition, the user must know how much force is required for the punching operation. In case of doubt, several types of spring deformations and settings may be required before obtaining the correct force. A further limitation is the service life of the mechanical spring, which is slightly too short and may not meet the increasing demand of the sheet metal forming industry.

  U.S. Pat. No. 6,182,545 discloses a different mechanism for attaching a punch to a punch retainer, the retainer comprising a retainer body, in which the punch retains with respect to the punch retainer. A locking mechanism is provided for fixing the. The locking mechanism may comprise a spring loaded ball that engages a groove of a punch or wedge mechanism set by a screw. The punch retainer of US Pat. No. 6,182,545 is similarly adapted to be fixed relative to the upper movable tool portion.

  The type of punch retainer shown in US Pat. No. 6,182,545 is common in the market. Examples of punch strippers are shown in EP 1 547 703 and US Pat. No. 4,993,295. A punch stripper with a mechanical spring for use with a punch retainer of the type disclosed in US Pat. No. 6,182,545 B1, is, for example, Meller Manufacturing, Plymouth, Michigan, USA. Manufacture Company). www. moellerpunch. com. reference.

  A punch stripper with a polyurethane element operates in a similar manner. There are two variations of the punch stripper. One operates in the same way as a punch stripper provided with a mechanical spring, but uses a polyurethane element instead of a mechanical spring. The other operates with polyurethane forming the entire punch stripper. While the two designs may seem simple, the polyurethane element must be adapted to the stripping force necessary to perform the intended function. Already in the design phase, the user must know both the length used and the intended dimensions / initial load in order to provide the desired force. Depending on the stripping force, there are many sizes to choose from. The service life of polyurethane elements is generally shorter than mechanical springs. Thus, the service life is a further limitation with polyurethane. Another limitation is the ability of the polyurethane to withstand repeated stresses while maintaining its dimensions because the material is susceptible to compression set or creep. Thus, polyurethane elements can not accommodate increased production rates without difficulty. In addition, polyurethane elements require more space because they expand radially when compressed.

  Another problem found when using a polyurethane element as a stripper and entering into direct contact with a metal sheet is that particles from the polyurethane element may adhere to the sheet. In those places where the polyurethane is in contact with the sheet, the particles may have a detrimental effect on the quality of the subsequently added lacquer due to the reduced ability of the ink to adhere.

  An example of a punch stripper with a polyurethane element is shown in EP 1 384 535. Punch strippers with polyurethane elements for use with punch retainers of the type disclosed in US Pat. No. 6,182,545 are sold by, for example, Lane Punch Corporation.

  U.S. Pat. No. 4,292,869 discloses a punch stripper in which a gas spring is used instead of a mechanical spring or polyurethane element. However, the punch stripper of U.S. Pat. No. 4,292,869 is arranged in a C-shaped portion, the first shank forms the upper tool portion, includes the punch and punch stripper, A shank forms the lower tool portion and includes a punch die. The pressure chamber is arranged at the base part of the C-shaped part, and the punch stripper piston can move the gas through the gap between the inner sleeve and the outer sleeve. The space between the inner sleeve and the outer sleeve communicates with the pressure chamber through a passage in which an oil soaked sponge is arranged for the purpose of providing a lubricant for the punch stripper piston.

However, the punch stripper shown in US Pat. No. 4,292,869 is so bulky that it is difficult to use with modern standard press tools.
U.S. Pat. No. 4,316,399 discloses a punch stripper in which the punch stripper piston is sealed to the punch and to the outer sleeve. The chamber in which the punch stripper piston can move is connected to an external pressure source. In this punch stripper, the retainer, punch and stripping part are formed as one unit.

As a result of this design, the risk of gas leakage is increased due to sealing against the punch. In connection with maintenance and punch replacement, the gas must be vented before the punch can be disassembled.
Thus, the punch stripper shown in US Pat. No. 4,316,399 is too bulky and difficult to use with modern standard press tools.

EP 0 622 135 discloses a punch tool which comprises a punch stripper including a gas spring and is intended to be mounted on a turret punching press.
EP 0 646 427 discloses a further development of the punch stripper shown in EP 0 622 135.

  The punch strippers shown in EP 0 622 135 and EP 0 646 427 are arranged in the axial direction of the turret punching press in the manner shown in EP 0 611 188. Adapted to be mounted in the cavity. In this type of mounting, the punch stripper itself is elastically suspended relative to the upper tool part by a lifting spring. The purpose of the lifting spring is to lift the entire assembly including the punch and punch stripper from the workpiece. A separate stripping spring provides the force necessary to accomplish peeling the workpiece from the punch. The gas chamber generated in EP 0 622 135 and EP 0 646 426 has only a stripping function. Furthermore, the punch strippers shown in EP 0 622 135 and EP 0 646 427 have a punch head which is actuated by the upper tool part of the press only during the actual punching operation.

The punch strippers shown in EP 0 622 135 and EP 0 646 426 are used for punching presses of the type shown in US Pat. No. 6,182,545. I can't.
There is currently a need for a compact punch stripper that can be used as an alternative or supplement to the punch strippers sold on the market.

US Pat. No. 6,182,545 EP 1 547 703 US Pat. No. 4,993,295 EP 1 384 535 U.S. Pat. No. 4,292,869 US Pat. No. 4,316,399 European Patent No. 0 622 135 European Patent 0 646 427 EP 0 611 188 EP 0 646 426

  The present invention relates to an improved punch stripper and a punching tool including the punch stripper. In particular, the present invention relates to a punch stripper adapted to be fastened to a punch retainer, which can be mounted on the movable upper tool portion of the press.

  In accordance with one non-limiting aspect of the present invention, a punch stripper is provided that is adapted to be fastened to a punch retainer of a press tool. The punch retainer includes a punch stripper piston and a pressure chamber adapted to spring load the punch stripper piston. The pressure chamber is defined by a gap between the inner sleeve and the outer sleeve. The punch stripper piston has a portion that can be displaced in the axial direction within the gap. Substantially the entire pressure chamber is located within the outer sleeve. As defined herein, “substantially the entire pressure chamber” means the space forming the pressure chamber, for filling / evacuating gas or for interconnecting with other similar punch strippers Exclude any ducts. By using a pressure chamber, a greater initial force can be obtained. Greater force can be used to improve punch performance in high strength sheet metal. However, this is not essential. By utilizing gas spring technology and forming a pressure chamber between the inner and outer sleeve assemblies, a more compact assembly can be obtained than existing assemblies. However, this is not essential. More compact assemblies are advantageous because today's press tools often have little space available. By regulating the pressure in the chamber, the required stripping force can be easily changed and a minimum number of variations of the punch stripper can be achieved. However, this is not essential. In addition, by using gas spring technology, the reliability of the punching process can be increased, which means that the greater stripping force and the punching operation are performed properly and with the desired quality. This is because it makes it possible to provide a better method for ensuring the above. However, this is not essential. Furthermore, a large amount of force generated by the mechanical spring can be avoided. However, this is not essential. The use of the gas spring technology of the present invention makes it possible to drill inclined holes and contours with the same reliability and quality as a conventional punch stripper with a straight profile, The punch stripper can withstand side loads generated by angles of up to 10 °, up to about 15-20 degrees under certain conditions, and has the same service life when used to drill straight holes It is because it has. However, this is not essential. By acting the punch stripper piston on the pressure chamber, an improved absorption of the impact force generated when the punch pierces the workpiece can be obtained. However, this is not essential.

  In accordance with another and / or alternative non-limiting aspect of the present invention, the pressure chamber includes a guide portion in which the displaceable portion can move, a shaft portion axially separated from the guide portion and larger than the guide portion. A chamber portion having an area. However, this is not essential. By using this configuration, the required volume of the pressure chamber can be obtained while allowing the outer dimensions of the punch stripper to be reduced to a minimum. However, this is not essential.

  In accordance with yet another and / or alternative non-limiting aspect of the present invention, the outer sleeve has a first portion with a first essentially constant inner cross section that forms a boundary surface of the guide portion; A second portion having a second inner cross-section that is larger than the first inner cross-section and that forms a boundary surface of the chamber portion. However, this is not essential. In this way, the outer sleeve with an annular cross-section may have a constant outer diameter and a varying inner diameter, ie a varying wall thickness. However, this is not essential. Alternatively or additionally, the outer sleeve may also have a varying outer diameter. However, this is not essential. For example, the outer sleeve may have an essentially constant wall thickness, but the chamber portion has a larger inner cross-sectional area and the guide portion has a smaller cross-sectional area. However, this is not essential.

  In accordance with yet another and / or alternative non-limiting aspect of the present invention, the inner sleeve has a first portion with a first essentially constant outer cross-section that forms a boundary surface of the guide portion; A second portion having a second outer cross-section that is smaller than the first outer cross-section and that forms a boundary surface of the chamber portion. However, this is not essential. In this way, the inner sleeve with an annular cross section may have a constant inner diameter and a varying outer diameter. However, this is not essential. Alternatively or additionally, the inner sleeve may also have a varying inner diameter. However, this is not essential. For example, the inner sleeve may have an essentially constant wall thickness, but the first portion has a larger outer cross-sectional area and the second portion has a smaller outer cross-sectional area. However, this is not essential. The inner sleeve may be fixed with respect to the punch. However, this is not essential. The outer sleeve may be fixed with respect to the punch. However, this is not essential. The portion of the punch stripper piston that is displaceable in the gap may be sealed against the inner sleeve and / or the outer sleeve. However, this is not essential.

  In accordance with yet another and / or alternative non-limiting aspect of the present invention, the punch stripper may include pressure indicating means for indicating the pressure in the pressure chamber. However, this is not essential. This makes it possible to avoid lack of pressure or inaccurate pressure in the punch stripper. However, this is not essential. Furthermore, it is possible to determine whether the punch stripper can be safely disassembled. However, this is not essential. The pressure indicating means may be adapted to indicate that the pressure in the pressure chamber exceeds and / or falls below a predetermined value. However, this is not essential. The pressure indicating means may be integrally formed with the punch stripper, for example, the outer sleeve and / or the base portion. However, this is not essential. The pressure indicating means may comprise a spring-loaded part, which can be seen from the outside of the punch stripper. However, this is not essential.

  In accordance with another and / or alternative non-limiting aspect of the present invention, a press tool is provided that includes a punch fastened to a punch retainer and a punch stripper fastened to the punch retainer. However, this is not essential. In the press tool, the punch retainer may be fastened to the stroke portion of the press tool. However, this is not essential. As defined herein, a “stroke portion” means a portion that generates press motion, ie, an eccentric press or a piston of a hydraulic press, or a runner of a screw press.

  In accordance with yet another and / or alternative non-limiting aspect of the present invention, a press tool is provided that includes at least two punch strippers. However, this is not essential. In one non-limiting embodiment, the pressure chambers of each of the at least two punch strippers are in fluid communication with each other to maintain substantially the same pressure in the respective pressure chambers of the at least two punch strippers. May be. However, this is not essential. The advantage of this arrangement is that the operator only has to fill the gas in one place without dismantling the punch stripper from the retainer. However, this is not essential. Furthermore, when the stripping force needs to be adjusted, the gas pressure can be regulated by all punch strippers simultaneously in a simple and flexible manner. However, this is not essential.

  In accordance with yet another and / or alternative non-limiting aspect of the present invention, a punch stripper is provided that is adapted to be fastened to a punch retainer of a press tool. However, this is not essential. The punch stripper includes a punch stripper piston and a pressure chamber adapted to apply a screw load to the punch stripper piston. However, this is not essential. The punch stripper includes pressure indicating means for indicating the pressure in the pressure chamber. However, this is not essential.

  In accordance with yet another and / or alternative non-limiting aspect of the present invention, any other optional, provided that the punch stripper disclosed above or a pressure chamber is used to achieve spring loading. A design punch stripper is provided. However, this is not essential. Non-limiting examples of such means that can be used in the present invention include US Pat. No. 4,292,869, US Pat. No. 4,316,399, European Patent 0 622 135. Or EP 0 646 427, all of which are incorporated herein by reference.

  In accordance with another and / or alternative non-limiting aspect of the present invention, there is provided a punch stripper adapted to be fastened to a punch retainer of a press tool, the punch stripper comprising a punch stripper piston and a pressure chamber. Including. The pressure chamber is adapted to spring load the punch stripper piston. The pressure chamber is defined, at least in part, by a gap between the inner and outer sleeves of the punch stripper. The punch stripper piston includes a displaceable portion that is axially displaceable within the pressure chamber gap. Substantially the entire pressure chamber is located between the inner and outer sleeves of the punch stripper. However, this is not essential. In one non-limiting aspect of the present invention, the pressure chamber includes a guide portion through which the displaceable portion can move. However, this is not essential. The chamber portion of the pressure chamber is axially separated from the guide portion of the pressure chamber. However, this is not essential. The chamber portion of the pressure chamber has a larger cross-sectional area than the guide portion. However, this is not essential. In another and / or alternative non-limiting aspect of the present invention, the outer sleeve has a first portion with a first essentially constant inner cross section forming a boundary surface of the guide portion; And a second portion with a second inner cross-section that is larger than the inner cross-section and forms a boundary surface of the chamber portion. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, the inner sleeve includes a first portion with a first essentially constant outer cross-section that forms a boundary surface of the guide portion; And a second portion with a second outer cross-section that is smaller than one cross-section and that forms a boundary surface of the chamber portion. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, the inner sleeve is secured to the punch. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, the outer sleeve is secured to the punch. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, the portion of the punch stripper piston that is displaceable within the gap is sealed against the inner sleeve and / or the outer sleeve. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, the punch stripper piston includes means for preventing it from rotating relative to the inner and / or outer sleeve. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, a pressure indicating means is included to indicate the pressure in the pressure chamber. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, the pressure indicating means is adapted to indicate that the pressure in the pressure chamber exceeds and / or falls below a predetermined value. The However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, the pressure indicating means is integrally formed with the punch stripper. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, the pressure indicating means includes a spring loaded portion that is visible from the outside of the punch stripper. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, a press tool is provided that includes a punch fastened to a punch retainer and a punch stripper fastened to the punch retainer, the punch retainer being a stroke of the press tool. Fastened to the part. However, this is not essential. In another and / or alternative non-limiting aspect of the present invention, the press tool includes at least two punch strippers. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, the pressure chambers of the at least two punch strippers maintain substantially the same pressure in the pressure chambers of the at least two punch strippers. They are in fluid communication with each other. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, it is fastened to a punch retainer of a press tool that includes a punch stripper piston and a pressure chamber adapted to spring load the punch stripper piston. A punch stripper adapted to the above is provided. However, this is not essential. Indicator means may be provided to indicate the pressure in the pressure chamber. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, the indicating means is adapted to indicate whether the pressure in the pressure chamber has exceeded a predetermined value and / or below it. Is done. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, the indicating means is an integral part of the punch stripper. However, this is not essential. In yet another and / or alternative non-limiting aspect of the present invention, the indicating means includes a spring-loaded portion that is visible from the outside of the punch stripper. However, this is not essential.

One non-limiting purpose of this document is to provide an improved punch stripper.
Another non-limiting object of the present invention is to provide a punch stripper that can be used as an alternative or supplement to the punch strippers currently sold in the market.

  Yet another non-limiting object of the present invention is to provide a punch stripper that minimizes the risk of errors and the risk of damaging equipment and people in the vicinity of the punch stripper.

  Yet another non-limiting object of the present invention is a punch stripper that can be used with punch retainers of the type shown in US Pat. No. 6,182,545, which is hereby first incorporated by reference. Is to provide.

These and other objects and advantages will become apparent to those skilled in the art upon reading and following the description taken in conjunction with the accompanying drawings.
In the following, reference may be made to the drawings illustrating various preferred embodiments in which the invention may take physical form, certain parts and means.

1a is a schematic cross-sectional view of a press tool 3a, 3b to which a punch retainer 2 having a punch 1 and a punch stripper 10 is mounted, and FIG. 1b is a punch retainer 2 having a punch 1 and a punch stripper 10 mounted thereon. It is a schematic sectional drawing of press tool 3a, 3b. 2 is a schematic cross-sectional view of a punch retainer 2 including the punch 1 and the punch stripper 10, and FIG. 2 'is a schematic cross-sectional view of the punch retainer 2 including the punch 1 and the punch stripper 10. 1 is a schematic side view of a punch stripper 10. FIG. 4a is a schematic plan view of the punch stripper 10 of FIG. 3 as viewed from above, and FIG. 4b is a schematic plan view of the punch stripper 10 of FIG. 3 as viewed from below. FIG. 5 a is a schematic plan view of the modified punch stripper 10, FIG. 5 b is a schematic plan view of the modified punch stripper 10, and FIG. 5 c is a schematic plan view of the modified punch stripper 10.

In the following, referring to the drawings, which are only for the purpose of illustrating a preferred embodiment of the present invention and are not intended to limit the present invention, FIG. 1 shows a press having an upper tool portion 3a and a lower tool portion 3b. Indicates a tool.
The lower tool portion 3b is provided with a punch die. The workpiece 5 may be a metal sheet and is arranged to be machined by the press tools 3a and 3b.

  The upper tool portion 3a has a punch retainer 2 on which the punch 1 has a punch stripper and is fastened by fastening means 18a, 18b (for example, screws, bolts, rivets, etc.). The fastening means may be a mounting screw / fastening bolt 18a, as shown in FIGS. 1a, 1b and 2, the shank being arranged in the lumen 18b of the base portion 14a of the punch stripper.

  In a non-limiting example of the present invention, the punch retainer 2 may be designed in any of the methods disclosed in US Pat. No. 6,182,545 (ie, the punch retainer punches the punch). It may have a locking mechanism for fixing to the retainer). As can be appreciated, other locking mechanisms can be used with the punch retainer. The punch retainer 2 may be fixed to the upper tool portion 3a by a suitable joint such as, but not limited to, a screw joint, a bolt, a rivet, welding or the like.

  The punch 1 is surrounded by a punch stripper 10. The punch stripper 10 works to a chamber pressurized by, for example, nitrogen gas and / or other types of gases (eg, air, inert gas, etc.) instead of a mechanical spring or polyurethane element, Designed.

  The punch stripper is formed from an outer sleeve 14, here in the form of a tube portion, which is attached to the punch retainer 2. The tube portion is fitted with an inner sleeve 13, here in the form of an inner piston rod, which is held in place by a locking ring 16. As can be appreciated, the inner sleeve can be locked in place in other or additional ways. The inner piston rod has a concentric axial through hole intended to receive the punch 1 and a fixing seal 15a arranged at one end thereof. An annular piston is mounted on the outer part of the tube, which moves between an outer position (see FIG. 1a) and an inner position (see FIG. 1b) during the punching operation. The outer position is limited by the piston 11 hitting the mechanical stop 19. A dynamic seal 15b is attached to the inner end 11b of the piston between the inner diameter of the tube (outer sleeve 14) and the outer diameter of the inner piston rod (inner sleeve 13). The outer sleeve 14 may be formed integrally with the base portion 14a so as to be formed together with the punch stripper body, for example, in one piece. The inner sleeve may also be formed with the punch stripper body, for example in one piece. The punch stripper body may be adapted to be detachably fastened to the punch retainer by fastening means 18a, 18b, for example, by the base portion 14a.

  The piston 11 can have a concentric axial through hole intended to receive the punch. As illustrated in FIG. 3, a rolled groove 17 may be formed on the side surface of the piston. Corresponding grooves may be formed on the inner surface of the tube portion adjacent to one end surface. Together, the rolled surface forms a rotational lock that prevents the piston 11 from rotating within the tube. An alternative mechanism is illustrated in FIGS. In this alternative mechanism, an opening, rolled groove or slot is inserted into the piston. As illustrated in FIG. 5 a, the slot 32 is positioned along the vertical or longitudinal axis of the piston 11. The outer sleeve 14 includes an opening 34 that is used to receive a pin or screw 36, as illustrated in FIG. 5c. The end of the pin or screw is inserted at least partially into the slot 32 of the piston, thereby inhibiting or preventing the piston from rotating within the tube. If desired, a seal stripper (not shown) can be attached to the other end of the tube portion for the purpose of removing dust particles from the lateral surface of the piston.

  The pressure chambers 12a, 12b are formed by a space between the outer sleeve 14 and the inner sleeve 13, that is, between the inner diameter of the tube portion, the outer diameter of the inner piston rod, and the seal. The pressure chambers 12a, 12b are filled through a valve 30 (see FIG. 2 ') attached to the tube portion. The filling pressure used may vary depending on the application and the pressure may be up to about 200 bar. Typically, the filling pressure is between about 20 and 100 bar, depending on the punching application.

  The punch stripper 10 operates as follows. That is, when the piston 11 joins the workpiece 5 in a downward motion, and the punch 1 continues the downward motion, the gas moves axially into the first portion 12a of the pressure chamber and the dynamic seal 15b. Is compressed in the pressure chambers 12a, 12b. The stripping force is generated by the gas that is compressed as the piston performs its working stroke during the punching operation and punches through the drilled hole without deforming or damaging the drilled hole. Help pull back one.

  In order to easily determine whether the pressure chambers 12a, 12b of the punch stripper are pressurized, a pressure indicator 20 may be integrated into the tube portion, for example adjacent to the filling valve 30. The pressure indicator 20 may comprise an inwardly biased elastic pin 21, possibly connected to the plate 24, which is pushed out when the pressure chambers 12a, 12b are pressurized. When there is no pressure in the pressure chambers 12a, 12b, the pin 21 is retracted. In this way, it is easy to check whether there is pressure in the pressure chambers 12a, 12b. Furthermore, the pressure indicator 20 comprises a resilient element 22 whose spring constant can be selected to indicate a pressure exceeding a predetermined value, and a seal 23 which may be in the form of an O-ring or the like. Good.

  In accordance with the embodiment shown herein, the longer pin 21 is integrated into the outer sleeve 14 and can be read directly along with the scale marks provided on the outer sleeve 14. A pressure scale similar to may be formed.

  Another way to determine whether the pressure chamber is pressurized is to connect the punch stripper to other visual indicators (eg, light, electronic instrument, etc.) and / or sound generation devices. Yet another or additional method of determining whether the pressure chamber is pressurized is to connect the punch stripper to an external pressure monitoring device. Thereby, the pressure in the punch stripper can be easily controlled and monitored from the outside of the punching tool. It is also possible to provide an electrical indicator, for example via a pressure transducer, which is connected via a control device for a signal specification device such as but not limited to a display, speaker, lamp or transmitter.

  If two or more punch strippers 10 are provided in the press tools 3 a, 3 b, they may be connected to each other, so that the pressure is substantially the same in all punch strippers 10. However, this is not essential. In this embodiment, the punch stripper may be connected to a control block that includes a gas filling device, a pressure reducing valve, overpressure protection, and / or a pressure that exceeds or falls below a predetermined value. You may have a pressure monitoring device to show that A pressure indicator as described above may be integrated into such a control block.

  Thus, the objectives set forth above have been achieved efficiently, among those that have become apparent from the foregoing description, and are consistent within the structures set forth without departing from the spirit and scope of the invention. Since changes may be made, it is intended that everything contained in the above description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. The present invention has been described with reference to preferred and alternative embodiments. Variations and alternatives will become apparent to those of ordinary skill in the art upon reading and understanding the detailed discussion of the invention provided herein. The present invention is intended to include all such variations and alternatives as long as they fall within the scope of the invention. The following claims are intended to cover all of the general and specific features of the invention described in this application, and all statements of the scope of the invention are expressed in the language between them. It is also understood that you may be told to enter.

Claims (21)

  A punch stripper adapted to be fastened to a punch retainer of a press tool comprising a punch stripper piston and a pressure chamber, wherein the pressure chamber is designed to spring-load the punch stripper piston, the pressure chamber being At least partially defined by a gap between the inner sleeve and the outer sleeve, wherein the punch stripper piston has a displaceable portion that is axially displaceable within the gap and substantially the entire pressure chamber Is located between the inner sleeve and the outer sleeve, and the pressure chamber includes a guide portion and a chamber portion such that the displaceable portion of the punch stripper can move therein. The chamber portion is axially separated from the guide portion. Is, the chamber portion punch stripper characterized by having a larger cross-section than the guide portion.   The outer sleeve has a first portion and a second portion, the first portion having a first inner cross section that forms a boundary surface of the guide portion of the pressure chamber, and the second portion The portion has a second inner cross-section, at least a portion of the second inner cross-section is larger than at least a portion of the first inner cross-section, and the second portion is a portion of the pressure chamber. 2. The punch stripper according to claim 1, wherein a boundary surface of the chamber portion is formed.   The first inner cross-section has an average cross-sectional area, the second inner cross-section has an average cross-sectional area, and the average cross-sectional area of the second inner cross-section is the average of the first inner cross-section. 3. The punch stripper according to claim 2, wherein the punch stripper is larger than a cross-sectional area.   4. The punch stripper according to claim 3, wherein the first inner cross section has a substantially constant cross sectional area.   The punch stripper according to claim 3 or 4, wherein the second inner cross-section has a substantially constant cross-sectional area.   The inner sleeve has a first portion and a second portion, the first and second portions being axially spaced from each other, wherein the first portion is the guide portion of the pressure chamber. And the second portion forms a boundary surface of the chamber portion of the pressure chamber, and at least a portion of the first and second portions of the inner sleeve have different cross-sectional areas. The punch stripper according to any one of claims 1 to 5, wherein:   The punch stripper according to claim 6, wherein the cross-sectional area of the first portion of the inner sleeve is substantially constant.   The punch stripper according to claim 6 or 7, wherein at least a part of the cross-sectional area of the second part is larger than the cross-sectional area of the first part.   The punch stripper according to any one of claims 1 to 8, wherein the inner sleeve is fixed to the punch.   The punch stripper according to any one of claims 1 to 9, wherein the outer sleeve is fixed to the punch.   11. A punch stripper according to any one of the preceding claims, wherein the displaceable portion of the punch stripper piston is sealed against the inner sleeve, the outer sleeve and combinations thereof.   The punch stripper piston includes rotation restraining means at least partially to inhibit or prevent the punch stripper piston from rotating relative to the inner sleeve, the outer sleeve, and combinations thereof. The punch stripper according to any one of claims 1 to 11.   The punch stripper according to any one of claims 1 to 12, further comprising pressure indicating means for indicating the pressure of the pressure chamber.   14. The punch according to claim 13, wherein the pressure indicating means is designed to indicate a combination in which the pressure in the pressure chamber exceeds a predetermined value, falls below a predetermined value, and a combination thereof. Stripper.   The punch stripper according to claim 13 or 14, wherein the pressure instruction means is formed integrally with the punch stripper.   The punch stripper according to any one of claims 13 to 15, wherein the pressure indicating means includes a spring-loaded portion that can be at least partially seen from the outside of the punch stripper.   The punch stripper according to any one of claims 1 to 16, wherein the punch stripper is at least partially connected to a press tool by a punch retainer.   The punch stripper according to claim 17, wherein the punch retainer is fastened at least partially to a stroke portion of the press tool.   The punch stripper according to any one of claims 1 to 18, further comprising a second punch stripper connected to the press tool.   The punch stripper of claim 19, wherein the pressure chambers of the two punch strippers are in fluid communication with each other.   21. A punch stripper according to claim 19 or 20, wherein the pressures in the pressure chambers of the two punch strippers are substantially the same.

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