JPH0319797A - Punching device and operation method thereof - Google Patents

Abstract

PURPOSE:To efficiently punch a work-difficult material into a neat cut face by setting at least one of the edge point angles in a punch and a die to less than 90 deg. with the punch and the die serving as upper and lower electrodes of a high frequency oscillator. CONSTITUTION:A punch 1 and a die 4 are engaged with each other to punch a workpiece 3. Here at least one of the edge point angles alpha, beta of the punch 1 and the die 2 is less than 90 deg., and the punch 1 and the die 2 are formed to serve for upper and lower electrodes of a high frequency oscillator 5. In this way, only a punched part of the workpiece 3 can be sufficiently heated, softened and cut, and punching work of good appearance with a smooth punching cut face without a break and a crack can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a punching device for punching out a product of a desired shape from a material such as a plate, and a method of operating the same. More specifically, the present invention relates to an apparatus and an operating method for punching a material that is difficult to punch, such as a brittle material, into a beautiful cut surface.

[Conventional technology Co-punching has the advantage of being simpler and shorter in processing time compared to mechanical processing such as router processing and drilling, so it is efficient in producing large amounts of material in the desired shape from relatively thin sheets. Used when removing well.

However, since the material separates due to plastic shear, the workpiece must have sufficient ductility in order to punch well, and in the case of brittle hard materials, cracks or cracks may occur on the punched surface. There are drawbacks such as:

As a means to improve this problem, various methods have been studied to heat the workpiece to give it sufficient ductility and punch it.

For example, there is a heating punch punching method in which the punch is heated and the punch and workpiece are brought into contact, and the heat transfer during this process softens the area around the punch in the workpiece. Vibration punching methods, which punch by generating shear heat around the punch, have been studied, but none have yet been completely satisfactory both technically and economically.

[The problem that the invention tries to solve! ] Described in JP-A-57-102310, micro vibrations are repeatedly applied to the upper and lower punches while the workpiece is restrained by the upper and lower punches, while preventing cracks in the workpiece.
The vibrating finishing punching method, which generates shear heat in the sheared area and punches out, requires a vibration mechanism, a special press with functions, and a mold, and in addition to the multi-311f equipment, the product shape is round, square, etc. It has the disadvantage of being limited to simple shapes.

On the other hand, in the heated punch punching method, only the punch is heated, so the clearance between the punch and die changes depending on the heating conditions due to dimensional changes in the punch due to thermal expansion.
Maintaining clearance accuracy is difficult, and uneven heating can cause the mold to stiffen.

Furthermore, since the workpiece is softened by external heat transfer from the heating punch, the punching speed must be slowed down in order to fully utilize the heating effect for punching, which also has the disadvantage of poor productivity.

The purpose of the present invention is to solve the above-mentioned drawbacks by using a heating method that is completely different from conventionally known punching methods, and to efficiently punch out difficult-to-process materials that have been considered unsuitable for punching into beautiful cut surfaces. It is an object of the present invention to provide a punching device and an operating method thereof that are excellent both physically and economically.

[Means and effects for solving the problem] As a result of intensive studies to overcome the shortcomings of conventional heating punching devices, the inventors of the woodworking industry decided to apply high-frequency energy locally to the shearing region of the workpiece during punching. It was discovered that electric heating is technically and economically superior, leading to the present invention.

That is, the first aspect of the present invention is a punching device having a double-blade punching die that cuts a workpiece by engaging a punch and a die, wherein the angle of the cutting edge of at least one of the punch and the die is less than 90 degrees. , a punching device characterized in that the punch and die are upper and lower electrodes of a high frequency oscillator,
The second is a method of operating the punching apparatus according to the first aspect of the present invention, which is characterized in that the workpiece is subjected to high-frequency dielectric heating while the cutting edges of the punch and the die are in contact with the workpiece.

The present invention will be explained in detail below.

The first punching device of the present invention has a double-blade punching die that cuts (punches) a workpiece by engaging a punch and a die.

In the present invention, the angle of the cutting edge of at least one of the punch and the die is less than 90 degrees, preferably 80 degrees or less. The more acute the cutting edge, the more advantageous it is for local heating of the workpiece, but on the other hand, the more acute the angle, the lower the durability of the cutting edge of the die or punch, which is not preferable. The most preferred angle is 80 degrees to 20 degrees.

In the present invention, the punch and die are connected to a high frequency oscillator and configured as upper and lower electrodes.

When punching a workpiece with the punching device of the present invention, the punch and die are engaged, but the punch may be pushed down, the die may be pushed up, or both may be operated and engaged. do not have.

In the second method of operating the punching apparatus of the first invention, the cutting edges of the punch and the die are in contact with the workpiece, preferably by 0.01 mm, preferably by 0.05 mm. High-frequency electrostatic heating is performed in a state in which the cutting edge has penetrated by approximately 1 mm, that is, in a state in which there is substantially no space between the workpiece and the cutting edge.

The workpiece used in the punching process by the punching apparatus and operating method of the present invention may be any dielectric material, such as synthetic resin such as methacrylic resin (PMMA).
, polystyrene, styrene-acrylonitrile copolymer, styrene-methyl methacrylate copolymer, polycarbonate (PC), vinyl chloride (PVC), polyester (PET). polyoxymethylene (POM),
Examples include nylon (Ny6, Ny66, etc.) and phenolic resins, but even polyolefins such as polyethylene and polypropylene, which do not inherently have polar groups and cannot be heated by high-frequency electric heating, have polar molecules dispersed in advance. It is good if it is.

In addition, a non-dielectric synthetic resin mixed with conductive electrons such as carbon generates heat not due to galvanic loss but due to ohmic loss due to conduction current, and this type of synthetic resin is also applicable.

As inorganic glasses, high lead glass, soda lime glass, etc., which have a large dielectric constant, are favorably used.

Further, even inorganic glass having a small dielectric loss can be used by adding polar molecules and conduction electrons in the same way as synthetic resins.

The punching process referred to in the present invention refers to the process of generating mainly shear stress in a required cross section of a material such as a plate, wire, or rod, and cutting the material into a desired size and shape.
A general term for processing methods that

The high frequency dielectric heating referred to in the present invention is 1 to 3000 Mtl.
A general term for dielectric heating using the z frequency. It also includes so-called microwave dielectric heating.

From the viewpoint of shortening the heating time, it is desirable that the high-frequency electric field strength applied to the workpiece be as large as possible within a range that does not exceed the dielectric breakdown voltage of the workpiece.

In the case of high-frequency dielectric heating, the electric power input to the object to be heated, that is, the dielectric loss occurring in the object to be heated, is determined by the frequency of the high-frequency electric field applied to the object to be heated (f (c/s)) and the electric field strength E (
V/m). The volume of the heated object is Ω (m31. The relative permittivity is ε
1. If the dielectric power factor is t'anδ, their product is
(5/9) X 10- 1 0Ωf E2εr 4a
Among them, ε1 and tanδ often have different values depending on the frequency f, so in order to efficiently heat the workpiece during punching, the electric field strength as well as the It is important to optimally match the relationship between dielectric properties and frequency.

The heating temperature of the punched part of the workpiece during punching varies depending on the type of workpiece, its punching characteristics, and shear separation characteristics, but for amorphous materials, the temperature is generally close to the softening temperature or glass transition temperature. It is recommended to set this.

Next, the present invention will be specifically explained using the drawings.

1 and 2 are cross-sectional views showing an example of the mold of the punching device of the present invention, and FIGS. 3 and 4 are enlarged views of the cutting edge of the mold.

Reference numeral 1 indicates a bonchi (upper electrode), and 2 indicates a material presser, which is made of a hard non-dielectric electrically insulating material.

3 is a workpiece, 4 is a die (lower electrode), and 5 is a high frequency oscillator.

The angle α of the cutting edge 6 of the punch 1 and the angle β of the cutting edge 7 of the die 4 are less than 90 degrees.

FIG. 2 shows a partially modified version of the mold shown in FIG. In FIG. 2, when the part of the workpiece punched with the punch 1 is removed and the part of the workpiece that is compressed and fixed with the die 4 and the material presser 2 is used as a product, the die 4
The angle γ of the cutting edge of the punch 1 is 90 degrees, and the angle α of the cutting edge of the punch 1 is an acute angle less than 90 degrees.

In FIG. 3, when the cutting edge 6 of the punch 1 or the cutting edge 7 of the die 4 becomes an acute angle, high frequency energy is concentrated on a portion 8 on a line connecting the cutting edge of the punch and the cutting edge of the die.

FIG. 4 shows the shape of the cutting edge of the die and punch of the present invention, and
An example of the positional relationship between a die, a punch, and a workpiece when high-frequency dielectric heating is performed in the present invention is shown.

(4-1) shows the method of the present invention in which high-frequency dielectric heating is performed with the cutting edge 6 of the punch 1 and the tip of the cutting edge 7 of the die 4 biting into the workpiece 3.

(4-2) is a case where there is a slight flat end 9 at the tip of the cutting edge 6 of the punch 1 and the cutting edge 7 of the die 4, and when the cutting edge bites into the workpiece, it is small enough to not cause a big hindrance. The presence of minute flat ends is included in the present invention. The length 10 of the flat end is 0.5 mm or less, preferably 0.2 m.
If it is less than m, it can be satisfactorily used in the present invention.

(4-3) is a case where the cutting edge 7 of the die 4 is very small, and the length 1l of the cutting edge is 1/3 to 1/3 of the thickness of the workpiece.
/20 can be satisfactorily used in the present invention.

In both figures shown in FIG. 4, the cutting edge has bitten into the workpiece, but in the present invention, if there is substantially no space between the cutting edge and the workpiece, the cutting edge is in contact with the workpiece. Just being there is good.

For example, when punching a sheet of polymethyl methacrylate or a sheet of polycarbonate, a protective masking film such as polyolefin is generally attached to the front and back of the sheet. It has sufficient effect even when it is bitten,
Of course, polymethyl methacrylate or polycarbonate with the cutting edge biting into it can be used well.

In the present invention, the workpiece is heated in this state by high-frequency dielectric heating to selectively and intensively heat only the punched portion before punching.

In the present invention, high-frequency dielectric heating is used to heat the shearing region of the workpiece. Unlike heating from the outside of a material by thermal radiation or conduction, high-frequency dielectric heating uses high-frequency electric power regardless of thermal conduction. It has the following characteristics: it can be heated rapidly in proportion to the temperature of This is because it is excellent for uniformly heating materials locally and in a short period of time.

The reason why only the sheared area of the workpiece is locally heated during punching is that by applying a local high-frequency electric field, the heat can be locally concentrated, which makes it easier to heat uniformly, and that it reduces the chance of damage to the punched product caused by thermal factors. This is because there is less deformation and warpage, and the dimensional stability of the punched product is good.

The punching die used in the present invention must have a structure that can locally heat the sheared area of the workpiece by high-frequency galvanic heating, and the acute angle of the cutting edge of the punch or die will cause significant local heating. It was found to be effective,
This led to the invention of wood. That is, the angle of the cutting edge of the punch or die of the punching device of the Wood invention is less than 90 degrees.

When the angle of the cutting edge of the punch and die becomes acute, the energy of high-frequency dielectric heating concentrates on the line connecting the cutting edge of the punch and die, that is, where the punch is to be punched, heating it locally and softening it. .

Therefore, since the sufficiently softened portion is cut, no cracks or cracks occur in the workpiece, and smooth cutting and punching can be achieved.

Generally, only one side of the sheet cut by punching is often used as a product, and in this case, the cutting edge on the side to be used as a product is less than 90 degrees and close to 90 degrees, and the cutting edge on the side to be cut and removed is It is used to make the angle acute. By appropriately selecting the angle of the cutting edge on the side that will be used as a product, it is possible to punch out while minimizing deformation of the sheet at the broken portion on the product side.

Furthermore, when the cutting edges of the die and punch are made at acute angles, the cutting edges easily bite into the workpiece, and therefore the workpiece can be heated at high frequency with virtually no space between the cutting edge and the workpiece.

When high-frequency dielectric heating is applied to a workpiece with a space between the cutting edge and the workpiece, sparks are generated in the space,
Defects such as blackening of the surface of the workpiece may occur, but in the present invention, by performing high-frequency dielectric heating while the cutting edge is in contact with, preferably biting into, the workpiece, sparks are prevented and the workpiece is heated. This prevents defects occurring on the surface of the processed material12.

[Example 1] The double-blade punching die shown in FIG. 1 was used, and the angles α and β of the cutting edges of the punch and die were each 45 degrees. 2 mm thick polymethyl methacrylate (manufactured by Asahi Kasei Kogyo ■, Delaglass A) was used as the workpiece 3, and the frequency was 40 MHz.
The upper electrode of a high frequency oscillator 5 with an output of 3 KW was configured as a punch 1, and the lower electrode was configured as a die 4. After cutting the cutting edges of the die and punch into the workpiece 3 by about 0.1 mm, the shearing region was heated by high-frequency electrolysis to about 100° C., and punched out at a shear rate of about 10 mm/sec.

The product was punched through with a low load of approximately 500 kg without cracking.

The sheared cut surface was very beautiful.

[Effects of the Invention] According to the punching device and operating method of the invention, only the punched portion of the workpiece can be sufficiently heated and softened, so that the cut surface is smooth and the punched part has a good appearance without cracks or cracks. Can be processed.

In addition, methacrylic resin products and the like, which are brittle materials and could only be shaped into desired product shapes by special machining such as router processing, can now be obtained by an economical punching method.

[Brief explanation of drawings]

FIGS. 1 to 4 are drawings showing a section of a mold according to the present invention, and a portion according to the present invention.

Claims (3)

[Claims] (1) A punching device having a double-blade punching die that cuts a workpiece by engaging a punch and a die, wherein the angle of the cutting edge of at least one of the punch and the die is less than 90 degrees; A punching device characterized in that these are upper and lower electrodes of a high-frequency oscillator. (2) The punching device according to claim 1, wherein the angle of the cutting edge of at least one of the punch and the die is 80 degrees or less and 20 degrees or more. (3) The method of operating a punching apparatus according to claim 1 or 2, wherein the workpiece is subjected to high-frequency dielectric heating while the cutting edges of the punch and the die are in contact with the workpiece.