JP4142408B2 - Mold manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a mold for injection molding, and more particularly to a method of manufacturing a mold used for injection molding of a large molded product such as 600 mm × 800 mm by electric discharge machining. is there.
[0002]
[Prior art]
There are various means for manufacturing a mold for injection molding, and one of them is electric discharge machining. There exists a thing shown by patent document 1 as an example of the processing method which performs this electric discharge machining. This Patent Document 1 discloses the following processing apparatus, which will be described with reference to FIG.
[0003]
As shown in FIG. 10, a processing apparatus 30 includes a holding base 32 that holds a mold 31 to be processed, a motor 33 that is provided in the holding base 32 and moves the mold 31 in the front-rear direction of a horizontal plane, and a mold. Motor 34 that moves 31 in the horizontal direction of the horizontal plane, electrode holder 35 that is arranged to face the mold 31 in the vertical direction, support portion 36 that supports this, and support portion 36 that moves in the vertical direction And a control device 38 for controlling the operation of the entire processing apparatus.
[0004]
The control device 38 includes an operation control unit that controls the operation of the motors 33, 34, and 37, and a high voltage application unit 39 that applies a high voltage between the mold 31 and the electrode holder 35. It has been.
[0005]
The above is the processing apparatus described in Patent Document 1. In Patent Document 1, when a workpiece having a complicated shape such as an insert of an injection mold is processed using such a processing apparatus, electrodes for a plurality of steps are provided on the electrode holder 35. A technique for reducing the work of exchanging electrodes and improving the processing accuracy by holding and moving the mold 31 using the motors 33 and 34 for processing is described.
In order to manufacture a small mold, the above manufacturing method is useful, but when a large mold is manufactured, a completely different problem occurs.
[0006]
Next, the prior art in the case of molding a large mold will be described. FIG. 11 and FIG. 12 are explanatory diagrams for explaining a conventional mold manufacturing process. The mold processing apparatus is the same as the above-described processing apparatus.
[0007]
In FIG. 11, a copper or graphite master mold 50 is prepared to discharge-process the entire surface of a mold 51 (cavity side) to be processed at a time, and the master mold 50 faces the mold 51 at the time of electric discharge machining. The surface 52 is processed in advance into a shape that takes into account the finished shape of the mold 51, an insulating liquid is interposed between the master mold 50 and the mold 51, and a high voltage is applied to the master mold 50. By discharging between the master mold 50 and the mold 51, a part of the mold 51 is melted or evaporated to be processed into a predetermined shape.
[0008]
As shown in FIG. 12, when the distance between the master mold 50 and the mold 51 becomes short, the discharge is started, and the discharged portion of the mold 51 gradually melts or evaporates so that the mold 51 forms the discharge surface 52. It is dug down according to.
[0009]
At this time, gold is moved while moving the master die 50 in a fine spiral shape during electric discharge machining so that the finish does not deteriorate even if the subsequent polishing step is omitted (hereinafter, such movement is referred to as swinging movement). The mold 51 is processed. Such a processing method is generally called rocking processing and is a well-known technique.
[0010]
[Patent Document 1]
JP-A-5-228742 (FIG. 1 etc.)
[0011]
[Problems to be solved by the invention]
However, when electric discharge machining is performed on a large mold of, for example, 600 mm × 800 mm, the master mold 50 becomes too heavy, and it is difficult to hold the master mold 50 in a machining apparatus used for electric discharge machining. The problem peculiar to the mold occurs.
[0012]
Of course, this problem does not occur if a large processing device that can hold any shape is created, but it is not realistic to make a processing device according to the size of the mold, and it has a predetermined size. It is desirable to adopt a processing method that flexibly corresponds to the size of the mold using the above processing apparatus.
[0013]
[Means for Solving the Problems]
Therefore, in the present invention, one surface of the master mold is a discharge surface that discharges to the mold, and the discharge surface is previously formed into a shape to be processed on the work surface of the mold, and the discharge surface and the In the method of manufacturing a mold, the discharge surface is brought close to the processing surface while a high voltage is applied to the processing surface to generate a discharge, and the processing surface is processed into a predetermined shape. A solution method of a mold manufacturing method, wherein a machining surface is divided into a plurality of regions, the discharge surface is formed for one of them, and the die is machined by electric discharge machining for each region And
According to this method, since electric discharge machining is performed for each region of the surface to be processed, the size of the master mold to be manufactured can be sufficiently maintained.
[0014]
Here, when the mold manufacturing method is used, the following problems may newly occur. That is, since the work surface of the mold is divided and formed for each region, a minute step may be formed at the boundary between adjacent regions.
[0015]
If this step is formed, the step appears on the surface of the product when the product is molded by injection molding or the like using the mold, and the quality is remarkably impaired.
[0016]
Therefore, in the present invention, in the above-described mold manufacturing method, when electric discharge machining is performed for each region, a part of the region to be processed has an overlapping portion that overlaps a part of the adjacent region. Is the solution.
[0017]
According to this solution, a step does not occur in the vicinity of the boundary of the region. Therefore, even when a product is molded by injection molding or the like, a high-quality molded product is provided without impairing the quality of the product. It becomes possible.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
A method for manufacturing a mold according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory view of a mold processing apparatus suitable for use in the manufacture of a mold according to an embodiment of the present invention.
[0019]
As shown in FIG. 1, a processing apparatus 10 includes a holding base 12 that holds a mold 11 to be processed, a motor 13 that is provided in the holding base 12 and moves the mold 11 in a horizontal plane, for example, in the front-rear direction, A motor 14 that moves the mold 11 in a direction opposite to the moving direction of the horizontal motor 13, a support section 16 that supports a master mold 15 that is disposed to face the mold 11 in the vertical direction, and a support section 16. A motor 17 that moves in the vertical direction and a control device 18 that controls the operation of the entire processing apparatus are provided.
[0020]
The control device 18 includes an operation control means 20 that controls the operation of the motors 13, 14, and 17, and a high voltage application means 19 that applies a high voltage between the mold 11 and the master mold 15. Yes.
[0021]
The mold 11 is larger than the master mold 15 having the maximum weight that can be held by the processing apparatus 10, and the surface facing the support portion 16 when the holder 11 is disposed is the processing surface 8.
[0022]
The master mold 15 is a mold having a weight close to the maximum weight that can be held by the processing apparatus 10 and is made of graphite or copper. Further, a surface 7 (hereinafter referred to as a discharge surface 7) that faces the holding table 12 when supported by the support portion 16 among the surfaces of the master mold 15 is formed by machining the work surface 8 of the mold by electric discharge machining. For this purpose, it has been processed in advance. In addition, since graphite and copper have a higher specific gravity, a master mold 15 that uses graphite can be used.
[0023]
FIG. 2 is a view showing an example of a state in which the work surface 8 of the mold 11 is divided into regions according to the size of the discharge surface 7 of the master die 15. The description will be continued with reference to FIG. As shown in FIG. 2, the work surface 8 of the mold 11 is divided into three areas such as an area A, an area B, and an area C, and adjacent areas are divided so as to partially overlap. For the sake of explanation, a portion where the region A and the region B overlap is referred to as a region AB, and a portion where the region A and the region C overlap is referred to as a region AC.
[0024]
The master mold 15 uses the same mold when the same mold can be used for the areas A, B, and C. However, if different molds are required, the master mold 15 is created separately for each area. Is done. When each region is processed, molds corresponding to the number of processing steps are created, such as for primary processing, for secondary processing, and for finishing. That is, if there are three regions and three processing steps, nine master molds 15 are created.
[0025]
The operation of processing the mold 11 using the master mold 15 will be described with reference to FIGS. Reference is made to FIGS. 1 and 2 as appropriate. FIGS. 3 to 7 are explanatory diagrams for explaining how the die 11 is processed using the master die 15. Note that the operations described below are actually programmed and operated in the control device 18.
[0026]
First, referring to FIG. 3 and FIG. 4, a state of performing the primary processing on the region A will be described. The master mold 15A1 and the mold 11 are mounted on the processing apparatus, the holding table 12 is moved using the motors 13 and 14, and the position of the mold 11 is adjusted so that the master mold 15A1 is vertically above the area A. Do. FIG. 3 shows a state in which this position adjustment is completed, and the hatched portion in FIG.
[0027]
Insulating oil is supplied between the mold 11 and the master mold 15A1 by an oil supply means (not shown), and the high voltage applying means 19 is operated to increase the high pressure between the mold 11 and the master mold 15A1. Apply voltage. Next, the motor 17 is operated to lower the support portion 16 vertically downward, and the master mold 15A1 and the mold 11 are gradually brought closer to each other.
[0028]
When the distance between the master mold 15A1 and the mold 11 is short, the discharge is started, and the discharged portion of the mold 11 is gradually melted or evaporated, and the mold 11 is dug down according to the shape of the discharge surface 7.
[0029]
When performing this operation, the motor 13 and the motor 14 are operated, and the mold 11 is oscillated so as to draw a circle with a minute diameter. And if it digs to predetermined height, the control means 18 will stop the high voltage application means 19 and rocking | fluctuation operation. This state is the state shown in FIG.
Then, the motor 17 is driven to raise the support portion 16 vertically upward to raise the master die 15A1, and the primary processing for the region A is completed.
[0030]
Next, processing for the region B is performed. 5 and 6 are explanatory views showing the state of electric discharge machining for the region B. FIG. In FIG. 5, the portion painted in a satin finish corresponds to the region B.
[0031]
In processing the region B, first, the master die 15B1 for performing primary processing on the region B is attached to the support portion 16 instead of the master die 15A1. Then, the position adjustment is performed using the motors 13 and 14 so that the master die 15B1 is arranged vertically above the region B.
[0032]
At this time, as shown in FIG. 5, the region B is arranged so that a part of the region B overlaps the region A. Then, the machining apparatus 10 is operated and electric discharge machining is performed in the same manner as in the case of the area A, so that the portion corresponding to the area B is gradually dug down. At this time, processing is performed while adjusting so that the region B has the same depth as the region A.
[0033]
In this adjustment method, processing for the region B is temporarily stopped in a state shallower than the depth for the region A, the depth of the region B is compared with the depth of the region AB, and then a measuring instrument is used to determine how much to dig. And measure accurately. Then, further drilling is performed based on the measurement result. This operation is repeated, the region B is dug up to the same height as the region A while paying attention not to dig too much, and the processing on the region B is completed. This state is the state shown in FIG.
[0034]
At this time, by using the region AB as an index for measuring the processing error of the region A and the region B, it is possible to accurately dig up to the same height, thereby preventing the occurrence of a step.
[0035]
Next, processing for the region C is performed. The processing for the region C is different from the processing for the region B except that the processing region is different, and the description thereof is omitted, and the state is shown in the drawing. FIG. 7 is a diagram in which position adjustment before processing is completed, and FIG. 8 is a diagram illustrating a state after processing. In FIG. 7, a region filled with a lattice shape indicates a region C.
[0036]
The primary processing is completed as described above, and thereafter, the master die 15 is replaced for secondary processing and finishing, and the same operation is performed for processing. As a result, the mold 11 is finished in a desired shape and the processing is completed.
[0037]
Thus, even when a larger master mold than the master mold that can be held by the machining apparatus 10 is required when machining a mold by dividing into a plurality of regions, by electric discharge machining. The mold can be manufactured, and the step that may occur at the time of processing by providing a partially overlapping area when the mold is divided into areas such as the area AB or the area AC. It is possible to eliminate the problem and to manufacture a mold having a good finish.
[0038]
In the example described above, the processing steps are described as three steps, a primary step, a secondary step, and a finishing step. However, the number of steps is not particularly limited to this, and any number of steps may be used. Good. Further, as the master type material, graphite having a low specific gravity is convenient because the master type can be made larger, but the same technical idea can be applied to other materials.
[0039]
Furthermore, in the above example, the example of dividing the area into three with respect to one axis on the horizontal plane has been shown. However, the present invention is not limited to this. For example, as shown in FIG. You may divide | segment into a several area | region so that a boundary may be formed in the direction which cross | intersects.
[0040]
As described above, according to the mold manufacturing method of the present embodiment, when a mold is processed, a larger master mold than the master mold that can be held by the processing apparatus 10 is required. In addition, it is possible to manufacture a mold by electric discharge machining. Also, by providing a partially overlapping area when dividing the mold, such as area AB or area AC, the problem of steps that may occur at the time of processing is eliminated, and the finish is good A mold can be manufactured.
[0041]
【The invention's effect】
According to the present invention, when processing a mold, a mold larger than the master mold can be manufactured by electric discharge machining.
[0042]
When the die is divided into regions, by providing a partially overlapping region, it is possible to reduce the level difference that may occur during processing, and to manufacture a die with good finish.
[Brief description of the drawings]
FIG. 1 is a diagram related to a processing apparatus for manufacturing a mold according to an embodiment of the present invention.
FIG. 2 is a diagram showing a region of a work surface of a mold according to an embodiment of the present invention with respect to a master mold.
FIG. 3 is a cross-sectional view showing a state in which a master mold is disposed in a mold region A according to an embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a state in which processing on a region A of a mold according to an embodiment of the present invention is completed.
FIG. 5 is a cross-sectional view showing a state in which a master mold is arranged in a mold region B according to an embodiment of the present invention.
FIG. 6 is a cross-sectional view showing a state in which the processing on the region B of the mold is completed according to the embodiment of the present invention.
FIG. 7 is a cross-sectional view showing a state in which a master mold is arranged in a mold region C according to an embodiment of the present invention.
FIG. 8 is a cross-sectional view showing a state in which the processing on the region C of the mold according to the embodiment of the present invention is completed.
FIG. 9 is a view showing another example of the arrangement of the mold regions according to the embodiment of the present invention.
FIG. 10 is a diagram showing a schematic configuration of a conventional processing apparatus.
FIG. 11 is a diagram showing a manufacturing process of a conventional mold.
FIG. 12 is a diagram showing a manufacturing process of a conventional mold.
[Explanation of symbols]
7 ... Electric discharge surface, 8 ... Work surface, 10 ... Processing device, 11 ... Mold, 12 ... Holding stand, 13 ... Motor, 14 ... Motor, 15 ... Master mold, 16 ... Supporting part, 17 ... Motor, 18 ... Control device, 19 ... high voltage application means, 20 ... operation control means.

Claims (1)

One surface of the master mold is a discharge surface that discharges to the mold, and the discharge surface is formed in advance into a shape to be machined on the work surface of the mold, and between the discharge surface and the work surface. A method of manufacturing a mold for causing a discharge by causing the discharge surface to approach the work surface while applying a high voltage, and machining the work surface into a predetermined shape. In the method of manufacturing a mold, the step of performing electric discharge machining on one of the plurality of regions and defining the region is performed on each of the plurality of regions.
The step of performing electric discharge machining for each one region is adjacent when performing electric discharge machining so that a part of the one processing target region has an overlapping portion overlapping with a part of one adjacent processing target region. It is a process of drilling down and processing while adjusting to the same depth as the area ,
Already temporarily stop processing for the processing target area at a shallow state than the depth of the processed working region, the substeps of comparing the machining depth in the depth and the overlapping portion of the processing target region, if then how much digging Repeating the sub-step of measuring whether it is good and the sub-step of further digging in based on the result of the measurement, so that the depth of the already processed region and the region to be processed becomes the same. And a process for finishing the processing on the region to be processed .

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