KR100664817B1 - Holder for accurate positioning of a workpiece - Google Patents

Abstract

It consists of attachment elements for attaching the holder to a fixed carrier structure and fixing parts for securing the workpiece, in particular of a machine tool such as an erosion machine. A holder for accurately positioning a workpiece within the working area is disclosed according to the invention. To make the holder insensitive to variable rinse fluid pressure during machining of the workpiece, the holder or / and the workpieces are provided with at least one vibration damper described in four different forms. It is done.

Description

Holder for precise positioning of workpiece {HOLDER FOR ACCURATE POSITIONING OF A WORKPIECE}

1 is a perspective view showing a leveling head

Figure 2 shows a schematic plan view of the leveling head according to figure 1 with a vibration damper;

3 shows a schematic view of a segment of the leveling head according to FIG. 2, with a first embodiment of a vibration damper of the first form;

4 shows a schematic view of a detail of the leveling head according to FIG. 2, with a second embodiment of a vibration damper of the first form;

5 is a schematic side view of another embodiment of a leveling head with a vibration damper of the second form;

Figure 6 shows a schematic plan view of the leveling head according to figure 5;

7 is a schematic side view of another embodiment of a leveling head with a vibration damper of the second form;

8 is a schematic side view of a leveling head with another vibration damper of the second form;

9 is a schematic side view of a holder having a vibration damper and a workpiece of the second type;

FIG. 10 is a schematic side view of a mechanical chuck mounted on a worktable with a vibration damper of a second form; FIG.

FIG. 11 is a schematic side view of a leveling head with a third type of vibration damper having important parts of a wire erosion machine shown in dashed lines; FIG.

12 is a schematic plan view of the leveling head according to FIG. 11 without wire grinding machinery parts;

13 is a side view schematically showing a leveling head according to an alternative embodiment of the present invention;

14 is a schematic view of a mechanical chuck with a workpiece holder with a vibration damper of the second form;

15 is a side view schematically showing a leveling head with a vibration damper of the second form;

<Description of the symbols for the main parts of the drawings>

1: leveling head 2: upper part

3,4 adjusting screw 5,6 spring

9,11: Ja 13,14: Polishing machine

15: workpiece 20,22: tapped hole

30: vibration damper 32: screw

33: lower side 34: blind hole

44: bolt head 50: mat

51,52,53: groove 62: damper

63,67: block 68: fixed plate

92,94: Plate 102: Chuck

109,110 Vibration Damper

The present invention relates to a holder for the precise positioning of a workpiece within the working area of a machine tool, more particularly an erosion machine. The holder includes an attachment element for attaching to a fixed carrier structure and holding parts for securing the workpiece.

In the electromachining process of a workpiece, it is necessary to remove all the ultrafine particles removed from the workpiece from the adjacent work area so that the required precision of the machining does not decrease. To remove the particles, water-based rinse fluid is generally used for the workpieces in the work area. As cutting speed increases, larger amounts of particle powder must be removed. This removal requires that the rinse fluid pressure be increased.

In order to ensure that the position of the workpiece is not affected, the erosion process itself is the workpiece, since the erosion electrode, for example in the form of a cutting wire, is not in contact with the workpiece. No force on it. On the other hand, increased rinse fluid pressure, which is generally not exactly constant, acts directly on the workpiece and vibrates within the holder, lowering the accuracy of the workpiece position and consequently lowering the workpiece machining.

In order to solve this problem, it is conceivable to increase the mass of the holder beyond the conventional strength requirements. However, such holders are difficult to handle and the working area is reduced.

German patent application DE-A-41 39 272 discloses a sliding block with a supporting element, which is a packing material of non-metallic material, which is expected to dampen noise and vibration. surrounded by packing material.

The present invention is based on the conventional problem of developing a holder without being sensitive to rinse fluid pressure and without limiting the working area.

Thus, according to the invention, the above-mentioned holder comprises at least one vibration damper. The vibration damper absorbs vibration energy transmitted from the rinse fluid to the workpiece to the extent that the accuracy of the workpiece position is no longer dangerous. Furthermore, since the vibration damping element can be attached to the outside of the work area, the work area is not limited by the holder of the present invention.

If the holder is constituted by two parts which vibrate with respect to each other, a preferred embodiment of the invention employs a first type of vibration damper, the first vibration damper being provided on both ends of the holder. Connected to the components and attenuating their relative movement with respect to each other. Furthermore, the attenuation characteristics can be adjusted. In addition, the vibration damper is provided with a spring constant. As the vibration damping performance of the vibration damper increases, the spring constant also increases. If the holder has such a vibration damper, the natural frequency of the holder increases as the workpiece is attached to the holder. If the frequency of the excited vibration is close to the natural frequency, the vibration damper is adjusted in such a way that the natural frequency is further away from the frequency of the excited vibration.

For example, if one component is attached to a fixed wall and protrudes from the fixed wall and its free end supports the workpiece, another embodiment of the present invention is a vibration of the second type. A damper is used. Excited vibrations cause the parts to be subjected to tensile and compressive loads. Thus, for example, a vibration damper having intrinsic damping characteristics, such as a rubber form, is mounted on the outside of the part. Another group of suitable vibration dampers are generally based on chromium and iron alloys and can be conveniently sprayed at negative pressure on the surface of the holder or the part. It is made of alloy (High Damping Capacity Alloy, HDCM). The thickness of the coating to be sprayed on the alloy can range from 2 mm to 3 mm.

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This second type of vibration damper can be arranged between two parts, that is, between two steel plates of a clamping device. In this case, the damping material is primarily subjected to a dynamically changing shear load. Suitable embodiments of this second type of vibration damper are insulating foils having high damping properties. One example of this is an insulating foil 2552 sold by Minnesota Mining and Manufacturing (3M) of Saint Paul, USA. Thus, according to one variant of the invention, an insulating foil is provided between the chuck and the work table as a special workpiece holder. According to another embodiment of the invention, a damping material such as, for example, rubber is vulcanized on the upper and lower plates of the leveling head, as disclosed in US Pat. No. 5,769,561. can be vulcanized.

The third type of vibration damper comprises a structure such as a steel ball, for example, in which rubber is vulcanized and a damping material is provided. In this advantageous design of the invention, the rubber body is attached on the holder in a position proximate to the workpiece. The steel mass may be the holder itself to which the damping material is attached on the Han Chinese side. The natural frequency of the rubber damping material is much smaller than that of the holder. Therefore, the vibration energy transmitted to the holder from the rinse fluid pressure is mostly absorbed by the damping material. On the one hand, if the natural frequency of the damping material is approximately equal to one of the natural frequencies of the holder with the workpiece, these natural frequencies are attenuated and the workpiece vibrates in the opposite phase. That is, the workpiece vibrates 180 degrees out of phase with the holder, and as a result, the action of absorbing the vibration energy of the holder due to the damping material is improved. According to one criterion of the present invention, attachment of an easily adjustable vibration damper is provided.

Finally, according to another embodiment of the present invention, which provides a vibration damper of the fourth aspect of the present invention, two or more plates of the same size which are connected to each other and subjected to shear loads during vibration are of the same size. The vibration damper absorbs vibration energy by friction between plates that are screwed or cemented together to form a plate package. Alternatively another plate with a higher coefficient of friction can be inserted between the plates of the package.

Accordingly, the present invention provides the holder with different types of vibration dampers, depending on the specific design or use of the holder. In this regard, the vibration damper may advantageously have an adjustable spring constant and a damping constant.

Another solution to the problems on which the present invention is based is to provide a laminated holder in which the metal sheets are permanently connected to one another. Conveniently, friction coefficients are provided on adjacent surfaces of the larger metal seeks. Vibrations that excite the holder cause the metal sheets to move relative to each other. The energy of the relative motion is absorbed by the friction of the metal seeks. As a result, the vibration action is attenuated.

Furthermore, preferred embodiments of the invention are disclosed in the dependent claims. In the following the invention is described in more detail with respect to a leveling head as an example of a holder.

According to FIG. 1, the leveling head 1 is described in detail in US Pat. No. 5,769,561 and is referred to to more clearly describe the present invention. The leveling head 1 has an upper part 2 which is leveled in the Z direction with respect to the lower part 7 by adjusting screws 3 and 4. It can be leveled, and the lower part can be moved in the XY plane for the prestress formed by two sets of springs 5, 6, and can be moved in the spring or XY plane. have. In front of the lower part 7 a precision vise 8 according to US Pat. No. 4,925,168 is attached to the upper part 2. Between the jaws 9, 11 of the vise, a workpiece (not shown in FIG. 1) can be clamped. According to the invention, the upper part 2 with the precision vise 8 forms a holder for the workpiece 15 (of FIG. 11) and is machined by an erosion wire 12. The workpiece is precisely positioned in the X, Y and Z directions of the working area 16 of the wire erosion machine 13 and 14 for machining.

In the embodiment shown, the underside of the lower part 7 is provided with a dovetail profile 18 of the tenon hole structure so that the underside of the lower part 7 can be accurately positioned in the X and Z directions. On a fixed carrier structure (not shown) of the type disclosed in U.S. Patent No. 4,786,776 with a dovetail counterprofile, the side of the tenon structure is perpendicular to the X direction and parallel to the direction of the abrasive wire 12. Do. The carrier structure also has a stop that allows the lower part 7 to be accurately positioned in the Y direction.

Rinse fluid and supply and outlet to work area 16 are not shown in the figures. In some cases, the rinse fluid washes around the workpiece 15 at high pressure along the cut 17, at which the abrasive wire 12 performs work on the cut.

According to the invention, the holder 10 is provided with one or several vibration dampers. In the first embodiment shown in FIG. 2, the upper part 2 forms two tapholes 20, 22 spaced apart from each other in the Y direction in the Z direction. Each of the two tab holes 20 and 22 may have a vibration damper of the first type in one of the embodiments according to FIG. 3 or the embodiment according to FIG. 4.

In the embodiment according to FIG. 3, a vibration damper 30 of the first type comprises a screw 32, which in its upper part is an external thread and an internal hexagonal recess. 31 is provided, and the recess is drilled starting from the lower side 33 facing the inner hexagonal recess 31 to form a blind hole 34. A cylindrical bolt 36 is inserted into the blind hole 34, which is placed on top of the lower part 7 and is permanently connected to the screw 32 via a damper 38. The damper 38 is made of rubber material and is fixed to both the inner surface of the blind hole 34 and the outer surface of the cylindrical bolt 36. As shown, the entire length of the screw 32 may be screwed into the hole 20 or into the hole 22. The damper 38, which is subjected to a shear load while vibrating, can absorb the vibration energy transmitted from the rinse fluid to the holder 10 due to the elasticity of the damper to prevent the holder 10 from vibrating.

In the embodiment according to FIG. 4, the vibration damper 40 of the first form has the shape of a bolt 42, the head 44 of the bolt having an external thread, with respect to the head 44. The slightly tapered shaft 46 is somewhat shorter in length. The damper 48 of rubber material is fixed to the free surface of the shaft 46. In the unstressed state, the damper has a somewhat smaller diameter than the shaft 46. The pin 49 is fixed to the free lower surface of the damper 48. The pins have the same diameter as the shaft, the length of which is protruding from the lower surface of the upper part 2 and is dimensioned so that the pins can be placed on the upper part of the lower part 7. The damper 48 has the same energy absorption characteristics as the damper 38. An internal hexagonal recess located on the head 44 of the bolt is not shown. If the bolts 42 are screwed into the passage bore 20 more than shown, the cross section of the damper 48 increases so that the spring and damping coefficients change. do. Thus, the properties of the damper 48 can be adjusted by the bolt 42. Vibration dampers 40 are particularly suitable for these passage holes 20, 22, in which only an internal thread is provided on the upper side, in the inner flat cylindrical hole 41. The female thread extends downwardly.

In the embodiment of the present invention according to Figs. 5 and 6, a rubber mat (mat) 50, which is a material that absorbs vibration of the vibration damper of the second aspect, is an upper part of the upper part (2). (19) and permanently connected to the upper part (2) by cementing or vulcanizing. For the set screw 3, 4 and the set of springs 5, 6, the mat 50 has grooves 51, 52, 53, 54. The mat 50 is about one third the thickness of the upper part 2. However, the choice of thickness is not limited. As an alternative to attaching the rubber material, an HDCM alloy can be sprayed onto the upper portion 19 as described above.

FIG. 7 shows yet another embodiment of a vibration damper of the second type. The leveling head 1 has an upper part 2 and a lower part 7 to which a vise 8 with a workpiece 16 is attached. The vibration damper 58 of the second type comprises an insulating material such as rubber, which is vulcanized to the lower part of the upper part 2 and the upper part of the lower part 7 in a convenient manner. It becomes. In addition, the leveling head corresponds to the leveling head shown in FIG. 1.

Another embodiment of a vibration damper of the second form is shown in FIG. 8. Here, the upper part 72 of the leveling head 70, which is described as one part in the embodiments described above, is divided into two plates 74 and 76 having the same size in the XY plane. Are connected by screws. Between the plates, an insulating foil 75 or rubber, for example an insulating foil 2552 mentioned above, is inserted as the insulating material. The lower part and the vise 8 attached to the upper part 72 and securing the workpiece 15 are similar to the design described above.

Two other examples of the second type of vibration damper are shown in FIGS. 9 and 10. According to FIG. 9, the workpiece 85 is bound to the holder 82. In this case, an insulating material, for example one of the aforementioned insulating foils 84, is inserted between the workpiece 85 and the holder 82 or cemented for example. Lose. The work piece 85 is screwed together with the holder 82. FIG. 10 shows a work table 86, on which a mechanical chuck 88 is arranged above an insulating foil 89 arranged in a state inserted therebetween (FIG. It is attached as a holder for the workpiece (not shown).

11 and 12 show a third type of vibration damper for the leveling head according to FIG. 1. There are two dampers 60, 65, of which the vibration damper 60 is fixed on the side part 24 of the upper part 2, and the vibration damper 65 is the upper part 2. It is fixed to the side portion 26 of the opposite side. All of the vibration dampers are fixed at a position immediately adjacent to the precision vise 8. A flat anchoring plate 61, on which the outer surface is provided with a plate-shaped damper 62 made of rubber material, is screwed to the side portion 24. As shown in FIG. The outer side of the damper 62 supports a solid block 63. As an alternative, a solid block 63, for example in the form of a solid steel ball, can be embedded into the material of the damper. The solid block has a lower natural frequency than the vibrations excited in the upper part 2 so as to absorb the vibration energy of the upper part 2. The vibration damper 60 fixed to the side of the upper part 2 does not increase the height of the leveling head 1 so that the effective working area is not reduced.

The vibration damper 65 is configured exactly the same as the vibration damper 60. Thus, the solid block 67 is permanently connected to the outer side of the anchoring plate 68 over the plate-shaped damper 66, and the outer side of the fixing plate is connected to the outer side portion 26. It is screwed in. Inserting an anchoring plate 61, 68 between the dampers 62, 66 and the solid block 63, 67 on the one hand and the upper part 2 on the other hand is a vibration damper. Allow 60,65 to be replaced so that their natural frequency, attenuation characteristics and their dimensions can be adjusted to the respective application.

Optionally, the two vibration dampers 60, 65 are workpieces which are not machined by the erosion wire 12 but are located between the jaws 9, 11 of the precision vice 8, for example. Can be connected directly at the top and bottom of the part of (15).

Finally, FIG. 13 shows a vibration damper 90 in an application of the fourth form of the holder, ie for the upper part 2 of the leveling head 1. The vibration damper 90 comprises several flat plate packages of the same size, here plates 92 and 94, which are permanently connected to one another by screwing or cementing operations. It is connected to the upper part of the upper part 2 by screws 91, 93 and 95. The plate package extends in parallel with the upper part of the upper part 2 and has essentially the same size as the upper part. The vibration damping effect is a result of the plates 92 and 94, and when the upper parts 2 vibrate, the plates are sheared against each other and rub against each other. The plates can be made of metal or stronger plastics. Further, the vibration damping effect can be further increased by inserting another plate 96 having a large coefficient of friction and a thin thickness between the plate 92 adjacent to the upper part 2 and the upper surface of the upper part.

In addition, since the upper part is made from the package of the plates 92 and 94, which corresponds to the package of the metal sheet having the sandwich structure, the upper part 2 itself is formed on the metal sheets. Can be segmented by The upper surfaces of the metal sheets facing each other may be roughened to increase the coefficient of friction, or a friction plate corresponding to the plate 96 may be inserted.

Figure 14 shows a pallet 101 as another embodiment of the present invention. The pallet is mounted on a machine table 100 and supports a mechanical chuck 102. In this chuck 102, the workpiece holder 104 holding the workpiece 105 is fixed. The chuck 102 and the workpiece holder 104 may be constructed in the same manner as described in US Pat. No. 4,855,558. See the contents of this document. Thus, the upper portion of the toolholder 104 facing the chuck in a stationary state represents the flat surface portion referred to herein as reference numerals 106 and 108. When secured, the flat surface portions are supported with respect to the free front face (axial reference plane) of the pins 103, 107 which protrude from the chuck 102. According to the invention, the free front faces of the pins 103, 107 are provided with vibration dampers 109, 110 in the form of HDCM alloy as described above. The alloy prevents the axial reference planes from vibrating or allows the vibrations to be significantly attenuated to a minimum. These alloys are deposited by spraying in a vacuum at a thickness of 2 mm or less and then grounded to form a reference plane. Simpler embodiments do not require grinding. The chuck 102 is configured as a holder in accordance with the present invention.

Finally, FIG. 15 shows a side view of a leveling head provided with another embodiment of a vibration damper of the second type. The upper part 120 fixed on the lower part 7 is made of a porous material of an open cell structure, for example, a metallic cast part, and the cell is insulated. It is almost completely filled as material. In addition, the finished casting is immersed in a cauotchouc or rubber solution. After the casting has been saturated as the solution, the solvent is transferred through thermal treatment to allow the rubber to be vulcanized into the casting. The mechanical strength of the upper part 120 is provided by casting, and the cured rubber 122 damps vibrations. In an alternative embodiment, the upper part 120 may be made of a solid metal box, for example an insulating material in the form of a cured rubber, rubber ball or rubber package. Is bound in its hollow interior.

As an example the above description of the invention with respect to a leveling head can be used according to the invention and describes basically four different types of vibration dampers. The vibration dampers 30 and 40 of the first type shown in FIGS. 2 to 4 have dampers 38 and 48 made of rubber or rubber material, which are two objects, here screws 32 or heads. It is inserted between the screw head 44 and the bolt 36 or the pin 49, and by the rinse fluid pressure acting on the workpiece 15, the screw 32 or screw head ( 44 is set to vibrate with respect to the bolt 36 or the pin 49, wherein the workpiece is permanently connected to the upper part 2. Here, the damping capacity and the spring constant of the dampers 38 and 48 are the natural frequencies of the system composed of the dampers 38 and 48, the upper part 2, and the work piece 15. The natural frequency can be adjusted radially and axially through the material selection and its dimensions so as to deviate from the natural frequency of the vibration being excited by the rinse fluid.

The second form of the vibration damper is shown in FIGS. 5-10, wherein the dynamic characteristics of the holder 10 may be regarded as the dynamic characteristics of a solid material, for example a solid beam. . Thus, the two objects do not move relative to each other. It is sufficient to fix the damper 50 made of a solid material (solid material) having an internal damping performance such as, for example, rubber on the outer side of the holder 10.

In the vibration damper of the third type according to FIGS. 11 and 12, the dampers 62, 66 are connected to the mass bodies (solid blocks 63, 67), and each individual application, for example different rinse fluid pressures. In this way, the attenuation characteristics can be adjusted in a very simple way. In this respect, the same rubber material can be used. Furthermore, the vibration dampers 60 and 65 can be dimensioned in such a way that they can be installed as close as possible to the site where vibrations occur. As can be clearly seen from FIG. 11, the spatial conditions in the wire erosion machine 13, 14 are particularly limited in the Z direction. Arbitrary shape dimensions of the vibration dampers 60 and 65 are particularly advantageous in that the application does not require more space for the holder 10 in the Z direction.

Finally, the vibration damper of the fourth type according to FIG. 13 uses friction force between plates or metal sheets to absorb vibration energy.

Claims (24)

A working area of the machine tool, including attachment elements for attaching the mechanical chuck to the machine table and holding elements for securing the workpiece holder In a mechanical chuck for accurate positioning of a workpiece holder in The mechanical chuck comprises a vibration damper in the form of a flat insulating foil of vibration absorbing material facing the flat surface of the mechanical chuck. The mechanical chuck of claim 1, wherein the vibration damper has a damping property high enough to attenuate vibrations imposed on the mechanical chuck. The mechanical chuck of claim 1, wherein the vibration absorbing material is a rubber or a material such as rubber. 4. The mechanical chuck of claim 3 wherein the thickness of the insulating foil is smaller than the size of the flat surface of the insulating foil. delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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