WO2000006332A1

WO2000006332A1 - Die and surface treating method for die

Info

Publication number: WO2000006332A1
Application number: PCT/JP1999/002215
Authority: WO
Inventors: Toshio Moro; Akihiro Goto
Original assignee: Mitsubishi Denki Kabushiki Kaisha
Priority date: 1998-07-31
Filing date: 1999-04-26
Publication date: 2000-02-10

Abstract

A surface treating method for a die, wherein electrode consumable melted substance of a discharge electrode produced by a discharge energy by means of electro-hydraulic machining or its reactant is bonded to and deposited on the cutting edge side face (104) of a stamping die or the inner peripheral surface of a die hole of an extracting/extruding die to form a hard coating (108) consisting of the electrode consumable melted substance or its reactant on the cutting edge side face or the die hole inner peripheral surface and the hard coating (108) is finished by discharge machining or grinding, thereby providing a die which is equivalent or superior in service life to a cemented carbide die and high in precision even when a tool steel is used as its base metal.

Description

Description Mold and mold surface treatment method

The present invention relates to a metal mold such as a press die used for shearing such as punching and punching, a die for drawing, a die used for extrusion, and a die for metal processing such as a die for extrusion. The present invention relates to a mold surface treatment method. Background art

Pressing dies used for shearing such as drilling and punching require high wear resistance, especially at the cutting edge, in order to obtain the required durability (mold life), and are used for drawing and extrusion. Similarly, the drawing die and the extrusion die require high wear resistance on the inner peripheral surface of the die hole, which is the processing surface.

In general, press dies, drawing dies, and extrusion dies are made of high-hardness metal materials such as carbon tool steel and alloy tool steel, and have a rock hardness (C scale) of 64 Hrc with HRC = 64. The wear resistance is improved by heat treatment with a specified hardness.

Extending the life of these dies is one of the major issues at all, and the demands on the mold life are becoming stricter with the increasing precision and diversification of stamping, drawing and extrusion. With surface treatment by heat treatment, the abrasion resistance is insufficient, and it is becoming difficult to secure the required mold life.

For this reason, in molds that require long life and high precision, instead of using general tool steel, high-grade sintering of carbide powder of high melting point metal with iron-based metals such as Fe, Co, and Ni is used. Sintered hard metal has been adopted, and recently it is often used in press dies for manufacturing lead frames for semiconductors. However, the use of cemented carbide as a mold material has the disadvantage that it is expensive, the machining method is limited, the equipment cost is high, and the productivity is lower than in the case of tool steel. In the mold industry, there is a growing demand for high-performance mold materials to replace cemented carbide.

In the case of cemented carbide, since the hardness is about HV21200 in Pickers hardness, cutting is impossible at all. Limited. As described above, due to poor workability and high material prices, it is quite possible to respond to frequent changes in molds due to the model change of products. It will be impossible. However, in view of maintaining the tool life and machining accuracy, there is a reality that tool steel cannot be simply adopted.

To solve these problems, tool steel molds are improved in surface hardness by means of shot peening, etc. To harden the abrasion resistance, ceramic-based hard materials are made of PVD (physical vapor deposition), CVD ( Coating methods such as chemical vapor deposition have also been proposed, but they have not been sufficiently effective.

For example, shot peening is intended for work hardening and does not provide a drastic solution.Hard coatings formed by PVD or CVD coating must have a thickness of about several meters. And the adhesion strength is insufficient for the requirements of the mold, and the effect has not yet been achieved. In the case of PVD and CVD, there are also basic problems such as the high processing temperature and the softened hardness of the quenched material, and it is practically difficult to adapt.

Conventional methods such as carburizing and induction quenching are also used, but they are not as effective.

The present invention has been made in order to solve the above-mentioned problems, and even if the mold is made of tool steel as a base material, it is an excellent mold that is at least as good as a cemented carbide mold. It is an object of the present invention to provide a long-lasting and high-precision mold and a surface treatment method for the mold. Disclosure of the invention

The die according to the present invention is characterized in that the electrode-depleted molten material of the discharge electrode or the molten material generated by the discharge energy generated by the electric discharge machining in the liquid is formed on the side surface of the cutting edge of the press-working die or on the inner peripheral surface of the die hole of the drawing die. The hard coating is formed on the side surface of the cutting edge or the inner peripheral surface of the die hole by the electrode consumable molten material or its reactant, and the hard coating is finished by electric discharge machining or grinding. Things.

Mold according to another aspect of the present invention, a tool steel as a base material, wherein the hard coating is WC, Ti C, Z r C , VC, Nb C, carbides such as _{Ta C, T i B 2,} Z r B 2 , etc. It is based on a simple substance or a combination of nitrides such as boride, TiN and TrN.

Further, the surface treatment method of the mold according to the present invention is characterized in that a predetermined discharge gap is formed between the discharge electrode and the side surface of the cutting edge of the press working die or the inner peripheral surface of the die hole of the drawing / extruding die in the liquid. The discharge electrode generates a discharge between the side surface of the cutting edge or the inner peripheral surface of the die hole and the discharge electrode, and the molten material consumed by the electrode generated by the discharge energy or the reactant thereof is discharged to the side surface of the cutting edge or the inner peripheral surface of the die hole. The electrode-consuming molten material is formed on the side surface of the cutting edge or the inner peripheral surface of the die hole, and a hard film is formed by a reaction product of the electrode. After the film is formed, the surface layer of the hard film is subjected to electric discharge machining. Is to remove the blade or die hole to the final dimensions by grinding.

The surface treatment method of a mold according to the invention follows, the hard coating is WC :, Ti C :, Zr C, VC, NbC, carbides such as _{T a C, Ti B 2,} Zr B boride such as _2, T This is based on a single nitride or a combination of nitrides such as iN and TrN.

The surface treatment method of the mold according to the next invention is characterized in that the discharge electrode is a green compact formed by compression molding a hard metal powder such as Ti, Zr, V, Nb, Ta, or a powder of a hydride thereof. A hard coating is formed using electrodes or metal electrodes made of these metals, and using EDM oil containing HC as a machining fluid.

The surface treatment method of the mold according to the next invention has the same shape as the shape of the die hole and the depth of the die hole. A groove having the same depth as that of the die material is formed in the die material, a start hole for wire electric discharge machining is formed in the groove, and the hard coating is formed on the inner surface of the groove. Later, the die through hole is machined in accordance with the groove shape by wire electric discharge machining starting from the start hole, and at the same time, the surface layer portion of the hard coating is removed, and the blade portion is finished to the final dimensions. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a configuration diagram showing a first embodiment of a surface treatment apparatus used for carrying out a surface treatment method for a mold according to the present invention, and FIG. In the surface treatment method, a perspective view showing the formation of a modified layer on the side of the cutting edge of a die using a simple shape electrode, and FIG. 2 (b) shows the finishing process by wire electric discharge machining. FIG. 3 is a perspective view, FIGS. 3 (a) to (f) are explanatory views showing processing steps of a mold surface treatment method according to the present invention, and FIG. 4 is a mold surface treatment according to the present invention. FIGS. 5A and 5B are perspective views showing an embodiment in which the method is applied to a punching die. FIGS. 5A and 5B show an embodiment in which the die surface treatment method according to the present invention is applied to a drawing die. 6 (a) and 6 (b) are cross-sectional views showing a method of extruding a mold surface according to the present invention. Is a cross-sectional view showing the embodiment applied to engineering die. BEST MODE FOR CARRYING OUT THE INVENTION

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Exemplary embodiments of a mold and a mold surface treatment method according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a first embodiment of a surface treatment apparatus used for carrying out a mold surface treatment method according to the present invention.

This surface treatment device is a kind of electric discharge machine and has a superimposed structure of an X-axis table 1 movable in the horizontal X-axis direction and a Y-axis table 3 movable in the horizontal Y-axis direction. The work tank 5 is fixed on the work table 5. A processing material mounting table 9 is provided in the processing tank 7, and a press processing die as a processing material, in the illustrated example, a die mold 100 is mounted and fixed on the processing material mounting table 9. You. In addition, a processing liquid is supplied into the processing tank 7 from a processing liquid supply device (not shown), and the die 100 on the workpiece mounting table 9 is immersed in the processing liquid.

An electrode support head i 1 movable in the vertical Z-axis direction is provided above the processing tank 7, and a rotary electrode support device 13 is provided below the electrode support head i 1. ing. The electrode support device 13 exchangeably supports the simple shape electrode 15 by a thin rod, and can rotate the simple shape electrode 15 around the electrode axis. The simple shape electrode 15 has a round bar shape, and the outer diameter of the electrode is selected according to the size of the material to be processed. When the material to be processed is a die 100, the dimension may be set so that the simple shape electrode 15 is included in the die hole 102.

The X-axis table 1, the Y-axis table 3, and the electrode support head 11 are positioned and driven by the X-axis servo motor 17, the Y-axis servo motor 19, and the Z-axis servo motor 21, respectively. The sub-bodies 17 and 17, the Y-axis sub-bodies 19 and the Z-axis sub-bodies 21 are determined by the respective axes output by the locus movement control unit 25 of the numerical controller 23. Position controlled.

The trajectory movement control unit 25 of the numerical controller 23 receives the trajectory movement data (electrode path information) from the electrode movement trajectory generation CAM device 27, and based on the trajectory movement data, the X-axis, Y-axis, and Z-axis. Generate a position alignment for each axis.

When the surface treatment method for a press-working die according to the present invention is performed using the surface treatment apparatus having the above-described configuration, the die hole 102 is formed by grinding or wire electric discharge machining. In order to form the cutting edge 106 of the mold, the die 100 made of tool steel, which has already been formed, is set on the work table 9 and the machining fluid is stored in the processing tank 7. The die 100 on the workpiece mounting table 9 is immersed in the working fluid.

In the machining fluid in the machining tank 7, a predetermined discharge gap g (third part) is formed by cutting the cutting edge side surface 104 provided by the inner peripheral surface of the die hole 100 of the die 100 and the simple shape electrode 15 into a predetermined shape. Figure A pulse voltage is applied between the cutting edge side surface 104 and the simple shape electrode 15 so that a pulse discharge is generated. As a result, the electrode consumable molten material generated by the discharge energy or the reaction product of the electrode fluid and the machining fluid component adheres to the cutting edge side surface 104 connected to the cutting edge 106 formed by the opening edge of the die hole 102. A hard film 108 (see FIG. 2) of the electrode consumable molten material or its reactant is formed on the cutting edge side surface 104 in a relatively wide area.

The hard coating 108 is a hard coating having excellent wear resistance. Examples of the material of the hard coating 108 include carbides such as WC, TiC, ZrC :, VC, TaC, and Ti. B _2, Z r B _2, etc. borides, T i N, single nitrides such as T r N, or O shall the like combinations thereof. -Also, as the simple shaped electrode 15, a compacted electrode obtained by compression molding a hard metal powder such as Ti, Zr, V, Ta, etc., or a hydride powder thereof, or by using these metals Using a metal electrode, an electric discharge machining oil containing HC as the machining fluid, and the reaction between the electrode material and HC in the electric discharge machining oil, T i C :, Z r C ;, VC :, T a C A hard coating made of such a metal carbide can be efficiently and satisfactorily formed on the cutting edge side surface 104.

The method of forming the hard coating i 08 by the pulse discharge as described above conforms to a method called a discharge surface treatment method by gap discharge in liquid. This discharge surface treatment method is disclosed in No. 6 26, Japanese Unexamined Patent Application Publication No. Hei 8-2585741, Japanese Unexamined Patent Application Publication No. 9-198928, and Japanese Unexamined Patent Application Publication No. ing.

The hard coating 108 is formed uniformly in a plane over the entire circumference of the cutting edge side surface 104. To this end, the gap between the j-side 104 on the cutting edge side and the simple shaped electrode 15 is maintained at a predetermined value, and the fine simple shaped electrode 15 and the die to be processed are the die 1 It is necessary to relatively displace 0 and in accordance with the cutting edge side shape determined by the press working shape (die hole flat shape), and this relative displacement causes a hard coating 10 on the entire circumference of the cutting edge side surface 104. 8 can be formed. The relative displacement between the simple shape electrode 15 and the mold 100 following the cutting edge side shape can be performed by moving the X-axis table 1 in the X-axis direction and the Y-axis table 3 in the Y-axis direction. .

The trajectory movement control unit 25 provided inside the numerical control device 23 has a simple shape electrode 15 for surface treatment based on the electrode path information created in advance by the CAM device 27 for electrode movement trajectory generation. Is performed, that is, drive control of the X-axis table 1 and the Y-axis table 3 is performed so that the locus movement of the simple shape electrode 15 traces the cutting edge side surface 104. Here, the control of the simple shape electrode 15 in the Z-axis direction (depth direction) is made constant in accordance with the position of the cutting edge 106 in the Z-axis direction.

When using a cylindrical simple shaped electrode 15, it is possible to process the simple shaped electrode 15 while rotating it around its own axis, so that deformation of the shape due to electrode wear can be corrected. Since the electrodes can be uniformly consumed, the processing efficiency can be improved.

FIG. 2 (a) shows a die for forming a long hole, and a hard coating 108 is formed on the entire periphery of the cutting edge side surface 104. Here, the hard coating 108 is formed slightly thicker so that the dimension of the die hole is slightly smaller than the final dimension and a finishing allowance can be secured.

As described above, when the hard coating 108 is formed, as a finishing step, as shown in FIG. 2 (b), the surface layer of the hard coating 108 is removed by wire electric discharge machining. Finish the die hole 102 and the blade to the final dimensions. The wire electrode 31 used in the wire electric discharge machining is made of an electrode material such as copper which causes relatively little electrode wear.

As a result, the entire circumference of the cutting edge side surface 104 is covered with a hard coating 108 having a hardness of about HV = 250, such as TiC, with a pick hardness of approximately 400%. Even if it is made of conventional tool steel, the tool life is superior to that of cemented carbide dies, due to the high wear resistance of the cutting edge surface. Since the mold base material is a general tool steel, die machining such as die drilling is easily performed with high productivity. In addition, as a finishing step, the surface layer of the hard coating 108 is removed by wire electric discharge machining, so that the die hole 102 and the blade are finished to the final dimensions, so that a high-precision die 100 And high-precision press working can be performed.

Also, as shown in FIGS. 3 (a) to (、), a groove 112 having the same shape as the shape of the die hole and having the same depth as the die hole depth is formed in the die material 100a. At the same time, a start hole 1 i0 for wire electric discharge machining is formed through the groove 1 12 and a hard coating 108 is formed on the inner surface of the groove 112. Die hole 1Q2, which is a through hole, is formed by wire electric discharge machining starting from hole 110, and at the same time, the surface layer of hard coating i08 is removed and the blade is finished to the final dimensions. it can.

In this machining procedure, as shown in FIG. 3 (a), a start hole 110 for wire electric discharge machining is formed through a drill tool 51, and then, as shown in FIG. As shown in b), the groove 1 12 is machined by the end mill 53. Next, as shown in Fig. 3 (c), the inner surface of the groove 112 is hard-coated by a discharge surface treatment method using a simple-shaped electrode 15 by a submerged-gap discharge. After the hard coating 108 is formed, the wire electrode 31 is passed through the start hole 110, and wire electric discharge machining is started from the start hole 110 to form the groove. The die hole 102, which is a through hole, is machined according to the shape of 112, and at the same time, the surface layer of the hard coating 108 is removed, and the blade is finished to the final dimensions.

Note that, after the die hole 102 is formed to penetrate, a tapered back escape hole 114 can be formed.

As a result, the cutting edge can be easily and reliably formed even in a die having a narrow width.

The formation of the hard coating 108 as described above, the finishing of the hard coating 108, and as shown in FIG. 4, can also be applied to the cutting edge side 202 of the punch die 200. it can -To finish the outer diameter of the punch die 200 to the final dimensions by removing the surface layer of the hard coating 108 formed on the cutting edge side surface 202 of the die 200, it is necessary to use a die. As in the case of the mold 100, it can be performed by wire electric discharge machining, but in addition to this, as shown in FIG. 4, the grinding process is performed by a grinding wheel 41 using a grinding machine. Can also be performed.

Further, the formation of the hard coating 108 as described above, the finishing of the hard coating i08, and the inside of the die hole of the drawing die 300 as shown in FIGS. 5 (a) and 5 (b). As shown in the peripheral surface 302 and FIGS. 6 (a) and 6 (b), the present invention can also be applied to the inner peripheral surface 402 of a die hole of an extrusion die 400.

In any case, a hard coating 108 was formed on the inner peripheral surface 302 or 402 of the die hole by a discharge surface treatment method using gap discharge in liquid using the simple shape electrode 15 and the wire electrode 3 was formed. The surface layer of the hard coating 108 is removed by wire electric discharge machining (1), and the die hole is finished to the final dimensions.

As can be understood from the above description, according to the mold according to the present invention, the discharge generated by the discharge energy by the submerged discharge machining on the side surface of the cutting edge of the press working die or the inner peripheral surface of the die hole of the drawing / extrusion die. The electrode consumable molten material or its reactant adheres and accumulates on the electrode, and if the electrode consumable molten material is on the side of the cutting edge or the inner peripheral surface of the die hole, a hard film is formed by the reactant and the hard film is discharged. Since it is finished by machining or grinding, even if the tool steel is used as the base material, it exhibits the same or better mold life as the cemented carbide mold and high precision Press, bow ίPunching and extrusion can be performed.

Mold according to another aspect of the present invention, a tool steel as a base material, wherein the hard coating is WC :, T i C :, Z r C, VC :, N b C ;, T a carbide such as C, T i B ₂ , boride such as _{Z r B 2, T i N} , single nitrides such as T r N, or since it is due to a combination, making full use of special processing techniques that required when processing the cemented carbide alloy It can be manufactured with high productivity without requiring special know-how.

According to the surface treatment method of the mold according to the next invention, the discharge due to the liquid gap discharge A hard coating is formed on the side surface of the cutting edge or on the inner peripheral surface of the die hole by the surface treatment method, and a hard coating made of the electrode consumable molten material or its reactant is formed. After the coating is formed, the surface layer of the hard coating is removed by electric discharge welding or grinding. Since the cutting edge or the die hole is finished to the final dimensions, even with a tool steel-based mold, it exhibits an excellent mold life equivalent to or better than that of a cemented carbide mold, and has a long life. An accurate mold can be obtained.

Also, in order to machine cemented carbide, it is necessary to make full use of extremely difficult machining techniques.By using tool steel as the base material, special machining techniques and special know-how are required. It is possible to perform the mold processing with high productivity without performing the above.

According to the surface treatment method of a mold according to another aspect of the present invention, the hard coating is WC ;, T i C, Z r C ;, VC, N b C :, T a carbide such as C, T i B _2, Z boride such as _{r B 2, T i N,} T r single nitrides such as N, or since it is due to a combination, to improve the wear resistance of the cutting edge side or die hole inner peripheral surface, the mold life Is greatly improved. According to the surface treatment method of the mold according to the next invention, the reaction between the electrode material and the HC of the electric discharge machining oil causes the cutting edge side surface to be formed by a hard coating such as Tic, Zrc, VC; Since the coating is performed, the wear resistance of the side surface of the cutting edge or the inner peripheral surface of the die hole is improved, and the life of the mold can be greatly improved.

According to the surface treatment method of the mold according to the next invention, a groove having the same shape as the dice L-shape and having the same depth as the depth of the die hole is formed in the die material, and the wire is subjected to wire electric discharge machining in the groove. A hard film is formed on the inner surface of the groove, and after forming the film, the die through-hole is formed by wire electric discharge machining starting from the start hole, following the groove shape. Since the surface layer of the hard coating is removed and the cutting edge is finished to the final dimensions, even if the tool steel is used as the base material, the tool life is as good as or better than that of the cemented carbide mold. In addition, it is possible to obtain a high-precision mold, and it is possible to easily and reliably configure even a narrow cutting edge. Industrial applicability

As described above, the mold and the surface treatment method of the mold according to the present invention have the required durability. Pressing dies used for shearing, such as drilling and punching, which require high wear resistance, especially at the cutting edge, in order to obtain the moldability (die life). It is suitable for the surface treatment of metal working dies such as bow dies used for extrusion, extrusion dies, and extrusion dies, which require high wear and wear resistance on the inner peripheral surface.

Claims

The scope of the claims

1. Discharged electrode electrode consumables generated by the discharge energy from submerged discharge machining or the reactants thereof are deposited on the inner peripheral surface of the die side of the die or the die for extrusion. The electrode consumable molten material is formed on the side surface of the cutting edge or the inner peripheral surface of the die hole, a hard coating is formed by a reaction product thereof, and the hard coating is finished by electric discharge machining or grinding. Money to do

2. tool steel as a base material, wherein the hard coating is WC ;, T i C ;, Z r C, VC ;, Nb C, carbides such as _{T a C, T i B 2} , Z r B 2 etc. the boron of 2. The mold according to claim 1, wherein the mold is a simple substance or a combination of a nitride such as a nitride, a TiN, and a TrN.

3. In the working fluid, the cutting edge side of the press die or the pulling-out ・ The inner peripheral surface of the die hole of the extrusion die and the discharge electrode are passed through a predetermined discharge gap, facing each other, and the cutting edge side or the die hole A discharge is generated between the inner peripheral surface and the discharge electrode, and the molten material consumed by the electrode generated by the discharge energy or its reactant is deposited on the side surface of the cutting edge or the inner peripheral surface of the die hole. A hard coating is formed on the inner peripheral surface of the die hole by a melted electrode consumable material or a reactant thereof. After the coating is formed, the surface layer of the hard coating is removed by electric discharge machining. A surface treatment method for a mold, comprising finishing a part or a die hole to a final dimension.

4. The hard coating is W (:, T i C, Zr C ;, VC, carbides such as _{NbC :, TaC, T i B 2} , Z r B 2 , etc. borides, T i N, T r N such 4. The mold surface treatment method according to claim 3, wherein the nitride is a simple substance or a combination thereof.

5. As the discharge electrode, a powder of hard metal such as Ti, Zr, V, Nb, Ta, or a green compact electrode obtained by compression molding of these hydride powders, or a metal of these metals 4. The mold surface treatment method according to claim 3, wherein a hard coating is formed by using a metal electrode according to claim 1 and an electric discharge machining oil containing HC as a machining fluid.

6. A groove having the same shape as the shape of the die hole and having the same depth as the depth of the die hole is formed in the die material, and a start hole for wire electric discharge machining is formed in the groove so as to penetrate. Forming the hard coating on the inner surface of the groove, after forming the coating, processing the die through-hole according to the groove shape by wire electric discharge machining starting from the start hole, and simultaneously removing a surface layer portion of the hard coating; 4. The mold surface treatment method according to claim 3, wherein the blade portion is finished to a final dimension.