JP4594486B2 - Cavity forming mold manufacturing method and cavity forming mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a cavity forming mold for resin molding, a cavity forming mold, and a resin molded product molded using the cavity forming mold. More specifically, the present invention relates to a technique for forming a prototype of a cavity forming mold.
[0002]
[Prior art]
In a mold for molding ultra-precise parts such as plastic aspheric lenses, a space into which resin as a molded product is injected is called a cavity. Since this cavity dominates the quality of a molded product, high precision is required for dimensions and the like. For this reason, in the manufacturing method of the metal mold | die (cavity formation metal mold | die) which forms a cavity, finishing is performed by diamond bite cutting so that it may demonstrate below with reference to FIG.
[0003]
In order to manufacture a cavity forming mold, conventionally, as shown in FIG. 11, first, in a first step ST51, a base material 61 made of a steel material containing 2% to 5% chromium such as SKD61 is prepared. In the second step ST52, the original shape 62 is formed by rough machining within an error range of 20 to 200 μm. Next, quenching and tempering are performed in the third step ST53.
[0004]
Next, in the fourth step ST54, after electroless nickel-phosphorous plating is performed on at least the surface of the original 62 that forms the cavity, a thick nickel-phosphorous plating layer 63 having a thickness of 100 μm to 200 μm is formed. In the fifth step ST55, heat treatment is performed at a temperature of 300 to 400 ° C. to remove the stress of the nickel-phosphorous plating layer 63, and the hardness (HRC) is set to 50 to 54.
[0005]
Next, in the sixth step ST56, the entire original shape 62 is subjected to outer diameter processing with a grindstone to form a reference surface, and then in a seventh step ST57, the nickel-phosphorous plating layer 63 is roughened by diamond bit cutting. Perform shape processing. Thereafter, in the eighth step ST58, the nickel-phosphorous plating layer 63 on the cavity forming surface 64 is finished by diamond bite cutting to finish the cavity forming die 60. Here, since the depth cut by diamond cutting is in the range of 50 to 100 μm, the nickel-phosphorous plating layer 63 needs to have a film thickness of at least 100 μm to 200 μm.
[0006]
In such a manufacturing method, it is not possible to obtain high processing accuracy by a method in which diamond tool cutting is performed directly on a steel material. However, the nickel-phosphorous plating layer 63 is in an amorphous state. Therefore, unlike the case where the crystallized portion is cut by a diamond bite, the step due to the crystal grain boundary does not occur, and the machining can be performed with high accuracy. In particular, the electroless plating of nickel-phosphorus with a phosphorus concentration set to 10 to 15% has an advantage that the hardness and toughness necessary for diamond bite cutting can be obtained.
[0007]
[Problems to be solved by the invention]
However, electroless nickel-phosphorous plating is a rather laborious process, as will be described below with reference to FIG. That is, as shown in FIG. 12, in the electroless nickel-phosphorous plating step, first, ultrasonic cleaning, masking 66, and strike processing are performed on the original 62, and then plating is performed in the plating tank 67. Later, after cleaning, it is necessary to forward to the heat treatment step ST53.
[0008]
For this reason, the conventional manufacturing method has a problem that the manufacturing cost is high and the manufacturing period of the mold is long. In particular, the electroless nickel-phosphorous plating layer 63 needs to be a thick film having a thickness of 100 to 200 μm in view of the depth at which the diamond cutting tool is cut. Therefore, even in this respect, the manufacturing cost is high. In addition, when such a thick plating layer 63 is formed, bubbles easily enter the plating layer 63, and the plating layer 63 is likely to be peeled off or distorted when heat treatment is performed. As a result, there is a problem in that diamond cutting cannot be performed with high accuracy and the yield decreases. Furthermore, in the plating process, tremendous costs are incurred in managing the plating conditions such as the composition of the plating solution 68, and the material of the base material is limited such that the surface of chromium 13% steel cannot be electrolessly plated. There are also problems.
[0009]
  In view of the above problems, an object of the present invention is to perform machining such as diamond cutting with high accuracy without performing electroless nickel-phosphorus plating on a base material made of steel having a predetermined shape. By doing so, a manufacturing method of a cavity forming mold for resin molding that can reduce the manufacturing cost and improve the yield,andCavity formation manufactured by this methodProvide moldThere is to do.
[0010]
[Means for Solving the Problems]
  In order to solve the above problems, in the present invention, in the original form forming step for forming an original form for forming a cavity forming mold for resin molding,At least on the part that should be the cavity forming surface of the cavity forming moldIn a manufacturing method of a cavity forming mold for resin molding having a machining step of performing machining to finish the cavity forming die, in the original shape forming step,After forming a nickel-phosphorus sintered body by a pulse current pressure sintering method for a powder for sintering containing nickel-phosphorus, nickel-phosphorus is formed between the sintered body and a base material made of a steel material having a predetermined shape. In this state, the sintered body and the base material are joined to form the original shape, and in the machining step, at least the firing is performed. The machining is performed on a portion to be the cavity forming surface in the bonded body.
[0011]
  In the present invention, the cavity-forming surface of the cavity-forming mold is formed not by electroless plating but by a pulsed current pressure sintering method for sintering powder containing nickel-phosphorus. And machining. Therefore, a thick nickel-phosphorus portion that can be machined can be formed in a short time without performing electroless plating, so that the manufacturing cost can be reduced and the mold manufacturing period can be shortened. Also, unlike plating treatment, the pulsed current pressure sintering method is performed under pressure, so large bubbles do not enter the sintered body, and peeling or distortion occurs in the plating layer when heat treatment is performed. The yield is also improved. Furthermore, unlike electroless plating, condition management is easy and the material of the base material is not limited. Therefore, the manufacturing cost of the cavity forming mold can be reduced, and the yield can be improved.
[0012]
  In this case, when the nickel-phosphorous sintered body and the base material are joined in the original shape forming step, the sintering includes the nickel-phosphorus disposed between the sintered body and the base material. It is preferable to arrange an iron-based sintering powder between the powder for use and the base material. If comprised in this way, since the sintering powder arrange | positioned between the sintered compact of nickel-phosphorus and a base material will join with strong force with respect to both a sintered compact and a base material after sintering. After sintering, the sintered body does not peel off from the base material.
[0013]
  In another embodiment of the present invention, an original shape forming step for forming an original shape for forming a cavity forming die for resin molding, and at least a portion of the original shape to be a cavity forming surface of the cavity forming die A cavity forming mold for resin molding having a machining process for finishing the cavity forming mold by performing machining, and in the original shape forming process, a position adjacent to a base material made of a steel material having a predetermined shape The powder for sintering containing nickel-phosphorus is arranged in this state, and in this state, the original shape in which a sintered body of nickel-phosphorus is bonded to the base material is formed by a pulse current pressure sintering method, In the machining step, the machining is performed on at least a portion of the sintered body to be the cavity forming surface.
[0014]
  In the present invention, the cavity-forming surface of the cavity-forming mold is formed not by electroless plating but by a pulsed current pressure sintering method for sintering powder containing nickel-phosphorus. And machining. Therefore, a thick nickel-phosphorus portion that can be machined can be formed in a short time without performing electroless plating, so that the manufacturing cost can be reduced and the mold manufacturing period can be shortened. Also, unlike plating treatment, the pulsed current pressure sintering method is performed under pressure, so large bubbles do not enter the sintered body, and peeling or distortion occurs in the plating layer when heat treatment is performed. The yield is also improved. Furthermore, unlike electroless plating, condition management is easy and the material of the base material is not limited. Therefore, the manufacturing cost of the cavity forming mold can be reduced, and the yield can be improved.
[0015]
  In this case, it is preferable that an iron-based sintering powder is disposed between the base material and the sintering powder containing nickel-phosphorus in the original shape forming step. If comprised in this way, a sintered compact will not peel off from a base material.
[0016]
  In the present invention, in the original shape forming step,When the nickel-phosphorus sintered body is formed by the pulse current pressure sintering method, predetermined irregularities are formed on the press surface of the punch that is in contact with the portion to be the cavity forming surface in the sintered body. Thus, it is preferable to transfer the unevenness of the punch to the sintered body. If comprised in this way, since the required unevenness | corrugation can be previously formed in an original form, without performing machining with respect to an original form, machining time can be shortened.
[0017]
  In the present invention, the pulse-current pressure sintering method is any one of a discharge plasma sintering method, a discharge sintering method, and a plasma activated sintering method.
[0018]
  In the present invention, in the machining step, for example, the nickel-phosphorus sintered body is cut with a diamond tool.
[0019]
  The present invention also includes a cavity-forming mold manufactured by the above method.
[0020]
  In addition, the present inventionThe present invention also includes a resin molded product molded using the cavity forming mold manufactured by the above method.
[0021]
Since the cavity forming mold manufactured by such a method is inexpensive and has a short manufacturing period, it is possible to reduce the cost of the resin molded product and the manufacturing period.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. Before describing each embodiment of the present invention, the configuration common to each embodiment (pulse current pressure sintering technology / discharge plasma sintering technology and cavity forming mold for resin molding) will be described. Let me explain.
[0023]
[Discharge plasma sintering technology]
The discharge plasma sintering performed in the present invention will be described. Among the plasma sintering methods in which sintering is performed using plasma, the thermal plasma sintering method is a method in which a continuous and steady ultra-high temperature plasma is generated in a plasma flame at 5000 to 20000 ° C. in a vacuum vessel. Perform pressure sintering. On the other hand, in the discharge plasma sintering method performed in the present invention, as described below with reference to FIG. 1, particles are applied by applying a large ON-OFF DC pulse current having a frequency of several tens to 300 kHz. Utilizing discharge plasma due to transient arc discharge phenomenon just after the arc discharge occurring in the gap, particle surface purification activation due to discharge impact pressure, etc., electric field diffusion effect generated in electric field and thermal diffusion effect due to Joule heat Performed under pressure.
[0024]
FIG. 1 is an explanatory view showing the principle of the discharge plasma sintering method.
[0025]
As shown in FIG. 1, in the discharge plasma sintering apparatus 30, rod-shaped upper punch 32 and lower punch 33 are arranged above and below a graphite cylindrical die 31, and the upper punch 32 and lower punch 33 are It is disposed inside a chamber 39 having an atmosphere control mechanism 305 that can be sintered in a vacuum, an inert gas, or the atmosphere. The chamber 39 is supported by a frame (not shown) so as to be movable up and down, and can be opened and closed by a fluid cylinder (not shown). A pressurizing mechanism 36 is configured for the upper punch 32 and the lower punch 33, and the pressurizing mechanism 36 is a powder for sintering filled in the die 31 through the upper punch 32 and the lower punch 33. Pressurize. An upper electrode 34 and a lower electrode 35 are connected to the upper punch 32 and the lower punch 33, and a sintering power source 37 is configured for these upper electrode 34 and lower electrode 35. Further, the discharge plasma sintering apparatus 30 includes a control device 38 that controls the power source 37 for sintering and the pressurizing mechanism 36, and the control device 38 includes measurement results from the position measurement mechanism 301 and the temperature measurement mechanism 302. Is entered. Further, the control device 38 controls the water cooling mechanism 304 including the cooling system 303 in which the cooling passages 341 and 351 pass through the upper electrode 34 and the lower electrode 35, and also controls the atmosphere control mechanism 305.
[0026]
In order to perform sintering using such a discharge plasma sintering apparatus 30, first, the nickel powder 11 is refined by the ball mill 21, and then the nickel powder 11 and the phosphorus powder 12 such as red phosphorus are milled by the mill 22. Are mixed to obtain a powder 10 for sintering.
[0027]
Next, the powder 10 for sintering which mixed the nickel powder 11 and the phosphorus powder 12 in the cylindrical die | dye 31 made from a graphite is filled. In this state, the sintering powder 10 is compressed between the rod-like upper punch 32 and the lower punch 33.
[0028]
Next, pulse energization is performed between the upper electrode 34 and the lower electrode 35 connected to each of the upper punch 32 and the lower punch 33 in vacuum, and heating, temperature holding, and cooling are performed. Among these operations, for example, heating is performed by applying a pulse current of about 1000 to about 8000 A at 0.1 V to 5 V for 10 minutes. As a result, the temperature is about 800 ° C to about 1200 ° C. At this time, a first energization path comprising the upper electrode 34 -the upper punch 32 -the sintering powder 10 -the lower punch 33 -the lower electrode 35, the upper electrode 34 -the upper punch 32 -the die 31 -the lower punch 33 -the lower electrode And the pulse current flowing through the third energization path consisting of the second energization path 35, and the upper electrode 34 -upper punch 32 -sintering powder 10 / die 31 interface-lower punch 33 -lower electrode 35. As a result, the sintering powder 10 is appropriately sintered to become the sintered body 15, and the die 31 and the punches 32 and 33 are Joule-heated with a slight delay, and the sintered body 15 is kept warm. At this time, the time for maintaining the temperature is about 10 minutes to about 30 minutes, and the cooling is about 30 minutes. The total time required to complete the sintering under such conditions is about 2 hours.
[0029]
Thereafter, the sintered body 15 is taken out between the die 31 and the punches 32 and 33.
[0030]
In such a discharge plasma sintering method, various sintered bodies 15 can be obtained by changing the particle diameter of the nickel powder 11 and the blending ratio of the phosphorus powder 12. For example, a sintered body 15 obtained by sintering a sintering powder 10 containing 13 wt% red phosphorus (phosphorus powder 10) with respect to a nickel powder 11 having a particle diameter of 20 μm, and a nickel powder 11 having a particle diameter of 20 μm. On the other hand, the sintered body 15 obtained by sintering the sintering powder 10 containing 20% by weight of red phosphorus (phosphorus powder 10), the red phosphorus (phosphorus powder 10) is 13 with respect to the nickel powder 11 having a particle size of 1 μm. Sintered body 15 obtained by sintering powder 10 for sintering containing 10% by weight, sintering powder 10 containing 13% by weight of red phosphorus (phosphorus powder 10) with respect to nickel powder 11 having a particle size of 0.1 μm. As a result, a sintered body 15 obtained by sintering is obtained.
[0031]
Further, according to such a discharge plasma sintering method, a nickel-phosphorus sintered body alone can be obtained, and a nickel-phosphorous sintered body 15 and a base material made of steel or the like are placed between them. When the discharge plasma sintering is performed by filling between the die 31 and the punches 32 and 33 in such a state that the nickel-phosphorous sintering powder 10 is sandwiched between the nickel-phosphorous sintering powder 15 and the steel material, Can be joined to the base material. Further, when discharge plasma sintering is performed by filling the base material made of steel and the nickel-phosphorous sintering powder 10 together between the die 31 and the punches 32 and 33, the base material made of steel is made of nickel. -A phosphor sintered body 15 can be formed. Furthermore, when joining with the base material, in the nickel-phosphorus sintered material located near the base material, the mixing ratio of nickel-phosphorous is continuously increased from the position away from the base material toward the base material side. In addition, the ratio of components common to the base material is continuously increased, and instead, the compounding ratio of the components common to the base material is continuously reduced as the distance from the base material increases. In addition, it is possible to continuously increase the nickel-phosphorus compounding ratio. When spark plasma sintering is performed under such conditions, an inclined junction structure in which an interface whose composition changes rapidly is not formed is formed. Since this can be realized, it is possible to form a material in which a base material made of steel and a nickel-phosphorus sintered body are firmly joined.
[0032]
[Configuration example of cavity forming mold]
FIG. 2 is an explanatory view showing a configuration example of a cavity forming mold that constitutes a cavity in a resin molding machine. 3A and 3B are a side view showing a configuration example of a cavity forming mold and a cross-sectional view taken along the line AA ′ in FIG.
[0033]
In the present invention, the cavity forming mold shown in FIG. 2 is manufactured using the above-described discharge plasma sintering method. In FIG. 2, in the resin molding machine 1, two cavity forming molds 4 form a pair of cavities 2. In the resin molding machine 1, the cavity 2 is filled with resin through the sprue 5, the runner 6, and the gate 7 to mold a plastic molded product such as a plastic lens. The molded product is taken out by the ejector pin 8.
[0034]
In this embodiment, the cavity forming mold 4 has a structure shown in FIGS. 3A and 3B, for example. 3 (A) and 3 (B), the cavity forming die 4 is formed of, for example, a columnar base material 41 made of steel or the like, and a portion 42 connected to the base material 41 has a cavity at its end face. A cavity forming surface 44 that is recessed to form is formed.
[0035]
Here, the root portion 46 of the distal end portion 42 has a different configuration for each embodiment described later. In either embodiment, the most distal portion 45 including the cavity forming surface 44 is a nickel-phosphorus sintered body. Formed from. In addition, the dimensional accuracy of the cavity forming surface 44 dominates the molding quality, and the cavity forming surface 44 is finished by diamond cutting in any form.
[0036]
3A and 3B, two flow paths 411 and 412 are formed inside the base material 41, and these flow paths 411 and 412 are annular flow paths. 413 communicates. For this reason, the temperature in the cavity can be controlled by circulating cooling water or the like through the flow paths 411 and 412.
[0037]
[Embodiment 1]
FIG. 4 is a process diagram showing a method for manufacturing a cavity-forming mold for resin molding according to Embodiment 1 of the present invention.
[0038]
As shown in FIG. 4, in this embodiment, in the original shape forming process, first, a blank 410, nickel powder 11, and phosphorus powder 12 of a base material 41 (see FIG. 3) made of a steel material are prepared, Then, phosphorus powder 12 is mixed to obtain sintering powder 10.
[0039]
Next, the nickel-phosphorous sintering powder 10 is filled in the die 31 and the punches 32 and 33 described with reference to FIG. 1, and discharge plasma sintering is performed in this state. The most advanced portion 45 of the cavity forming mold 4 described with reference to FIG. 3A is formed by the sintered body 15 obtained by this sintering. On the other hand, the base material blank 410 is processed into a rough shape.
[0040]
Next, in the die 31 and the punches 32 and 33 described with reference to FIG. 1, the tip portion 45 including the base material blank 410, the nickel-phosphorous sintering powder 10, and the nickel-phosphorous sintered body 15. In this state, spark plasma sintering is performed.
[0041]
As a result, the base material 41 and the most advanced portion 45 made of the nickel-phosphorus sintered body 15 are joined together by sintering the nickel-phosphorous sintering powder 10, and the original shape 40 of the cavity forming mold 4 is formed. It is formed.
[0042]
Next, the original 40 is subjected to heat treatment at a temperature of 300 to 400 ° C.
[0043]
Next, a machining process is performed. In this machining process, first, outer diameter processing is performed on the original 40 by grinding using a grindstone, and the shape of the original 40 is close to the shape of the cavity forming mold 4.
[0044]
Next, of the original shape 40, rough shape processing is performed on the most advanced portion 45 made of the nickel-phosphorous sintered body 15 by diamond cutting to form the cavity forming surface 44.
[0045]
Thereafter, the cavity forming die 4 is finished by performing a finishing process on the cavity forming surface 44 in the most distal portion 45 of the original 40 by diamond cutting.
[0046]
As described above, in this embodiment, the most advanced portion 45 including the cavity forming surface 44 of the cavity forming mold 4 is not subjected to electroless plating, but by discharge plasma sintering with respect to the sintering powder 10 containing nickel-phosphorus. Then, the sintered portion (sintered body 15) is subjected to a finishing process (machining) by diamond cutting. Therefore, a portion made of nickel-phosphorus can be formed thickly and in a short time in a place where diamond bite cutting is performed by electric discharge plasma sintering without requiring time-consuming electroless plating. It can be reduced, and the mold production period can be greatly shortened. Further, unlike the plating process, the discharge plasma sintering method is performed under pressure, so that no air bubbles enter the most advanced portion 45 made of nickel-phosphorous, and when the heat treatment is performed, the plating layer Since there is no peeling or distortion, the yield is improved. Furthermore, unlike electroless plating, condition management is easy and the material of the base material 41 is not limited. Therefore, the manufacturing cost of the cavity forming mold 4 can be reduced, and the yield can be improved. Further, if a sufficient fine gap is ensured between the powders in the sintered body 15, a gas venting function at the time of resin molding can be provided.
[0047]
[Embodiment 2]
FIG. 5 is a process diagram showing a method for manufacturing a cavity-forming mold for resin molding according to Embodiment 2 of the present invention.
[0048]
As shown in FIG. 5, in this embodiment, in the original shape forming step, first, a base blank 410 made of steel, an iron-based sintering powder 44 made of a common component with the base 41 (see FIG. 3), The nickel powder 11 and the phosphorus powder 12 are prepared, and after the nickel powder 11 is refined, the phosphorus powder 12 is mixed to obtain the sintering powder 10.
[0049]
Next, as in the first embodiment, the nickel-phosphorous sintering powder 10 is filled in the die 31 and the punches 32 and 33 described with reference to FIG. 1, and discharge plasma sintering is performed in this state. The most advanced portion 45 of the cavity forming mold 4 described with reference to FIG. 3A is formed by the sintered body 15 obtained by this sintering. On the other hand, the base material blank 410 is processed into a rough shape.
[0050]
Next, in the die 31 and the punches 32 and 33 described with reference to FIG. 1, the base material blank 410, the iron-based sintering powder 44, the nickel-phosphorous sintering powder 10, and the nickel-phosphorus A state-of-the-art portion 45 made of the sintered body 15 is disposed, and discharge plasma sintering is performed in this state. At this time, between the base material blank 410 and the sintered body 15, at the boundary portion between the iron-based sintering powder 44 made of the same component as the base material and the nickel-phosphorous sintering powder 10, the powder Mixing each other, the nickel-phosphorous sintering powder 10 decreases from the position away from the base metal blank 410 toward the base material blank 410, while the iron-based sintering powder 44 increases. . In other words, as the distance from the base material blank 410 side increases, the nickel-phosphorous sintering powder 10 increases while the iron-based sintering powder 44 decreases.
[0051]
As a result, the base material 41 and the most advanced portion 45 made of the nickel-phosphorus sintered body 15 are joined by sintering the iron-based sintering powder 44 and the nickel-phosphorous sintering powder 10, The original shape 40 of the cavity forming mold 4 is formed. In addition, at the joint portion between the base material 41 and the most advanced portion 45, the nickel-phosphorous sintering powder 10 decreases from a position away from the base material blank 410 toward the base material blank 410, while an iron-based material is used. An inclined joining structure in which the sintering powder 44 increases is obtained.
[0052]
Next, the original 40 is subjected to heat treatment.
[0053]
Next, a machining process is performed. In this machining step, first, the outer diameter of the original shape 40 is processed using a grindstone so that the shape of the original shape 40 is close to the shape of the cavity forming die 4. Next, a rough forming process is performed on the most advanced portion 45 made of the nickel-phosphorous sintered body 15 in the original shape 40 by a diamond cutting tool to form a cavity forming surface 44. Thereafter, the cavity forming die 4 is finished by performing a finishing process on the cavity forming surface 44 in the most distal portion 45 of the original 40 by diamond cutting.
[0054]
As described above, even in this embodiment, a portion made of nickel-phosphorus can be formed at a place where diamond bite cutting is performed by spark plasma sintering without performing time-consuming electroless plating, thereby reducing manufacturing costs. It is possible to obtain the same effects as those of the first embodiment, for example, and the manufacturing period of the mold can be greatly shortened. Further, since the base material 41 made of steel and the nickel-phosphorus sintered body 15 (the most advanced portion 45) have an inclined joint structure, the joining strength between the base material 41 and the sintered body 15 is high. .
[0055]
[Embodiment 3]
FIG. 6 is a process diagram showing a method for manufacturing a cavity-forming mold for resin molding according to Embodiment 3 of the present invention.
[0056]
As shown in FIG. 6, in the present embodiment, in the original form forming step, first, a blank blank 410 made of steel, a nickel powder 11, and a phosphorus powder 12 are prepared. The powder 10 for sintering is obtained by mixing.
[0057]
Next, the base material blank 410 is processed into a rough shape.
[0058]
Next, the base material blank 410 and the nickel-phosphorous sintering powder 10 are placed in the die 31 and the punches 32 and 33 described with reference to FIG. 1, and discharge plasma sintering is performed in this state. As a result, a prototype 40 of the cavity forming mold 4 is formed in which the base material 41 and the tip portion 42 made of the nickel-phosphorus sintered body 15 are integrated by sintering.
[0059]
Next, the original 40 is subjected to heat treatment.
[0060]
Next, a machining process is performed. In this machining step, first, the outer diameter of the original shape 40 is processed using a grindstone so that the shape of the original shape 40 is close to the shape of the cavity forming die 4. Next, rough shape processing is performed on the tip portion 42 made of the nickel-phosphorus sintered body 15 in the original shape 40 by diamond cutting to form a cavity forming surface 44. Thereafter, the cavity forming die 4 is finished by finishing the cavity forming surface 44 of the tip portion 42 of the original shape 40 by diamond bit cutting.
[0061]
As described above, even in this embodiment, a portion made of nickel-phosphorus can be formed at a place where diamond bite cutting is performed by spark plasma sintering without performing time-consuming electroless plating, thereby reducing manufacturing costs. It is possible to obtain the same effects as those of the first embodiment, for example, and the manufacturing period of the mold can be greatly shortened.
[0062]
[Embodiment 4]
FIG. 7 is a process diagram showing a method for manufacturing a cavity-forming mold for resin molding according to Embodiment 4 of the present invention.
[0063]
As shown in FIG. 7, in this embodiment, in the original shape forming process, first, a blank blank 410 made of steel, an iron-based sintering powder 44 made of components common to the preform, nickel powder 11 and phosphorus powder 12. After the nickel powder 11 is refined, the phosphorus powder 12 is mixed to obtain the sintering powder 10.
[0064]
Next, the base material blank 410 is processed into a rough shape.
[0065]
Next, in the die 31 and the punches 32 and 33 described with reference to FIG. 1, the base metal blank 410, the iron-based sintering powder 44 composed of components common to the base material, and nickel-phosphorus sintering In this state, discharge plasma sintering is performed. At this time, at the boundary portion between the iron-based sintering powder 44 made of the same component as the base material and the nickel-phosphorous sintering powder 10, the powders are mixed and separated from the base material blank 410. While the nickel-phosphorous sintering powder 10 decreases from the base metal blank 410 toward the base metal blank 410, the iron-based sintering powder 44 increases.
[0066]
As a result, the original shape 40 of the cavity forming mold 4 is formed in which the base material 41 and the tip portion 42 made of the sintered body 15 are integrated by sintering. Moreover, in the part which contact | connects the base material blank 410 of the sintered compact 15, while a nickel- phosphorus component reduces toward a base material blank from the position away from the base material blank 41, it is in the inclination joining structure where an iron-type component increases. It has become.
[0067]
Next, the original 40 is subjected to heat treatment.
[0068]
Next, a machining process is performed. In this machining step, first, the outer diameter of the original shape 40 is processed using a grindstone so that the shape of the original shape 40 is close to the shape of the cavity forming die 4. Next, rough shape processing is performed on the tip portion 42 made of the nickel-phosphorus sintered body 15 in the original shape 40 by diamond cutting to form a cavity forming surface 44. Thereafter, the cavity forming die 4 is finished by finishing the cavity forming surface 44 of the tip portion 42 of the original shape 40 by diamond bit cutting.
[0069]
As described above, even in this embodiment, a portion made of nickel-phosphorus can be formed at a place where diamond bite cutting is performed by spark plasma sintering without performing time-consuming electroless plating, thereby reducing manufacturing costs. It is possible to obtain the same effects as those of the first embodiment, for example, and the manufacturing period of the mold can be greatly shortened. Further, since the base material 41 made of steel and the nickel-phosphorus sintered body 15 (tip portion 42) have an inclined joint structure, the joining strength between the base material 41 and the sintered body 15 is high.
[0070]
  [Reference example]
  Depending on the structure of the cavity forming mold 4, the base material 41 side may be formed by sintering, and an example thereof will be described with reference to FIG.
[0071]
  FIG. 8 illustrates the present invention.Reference exampleIt is process drawing which shows the manufacturing method of the cavity formation metal mold | die for resin molding which concerns on this.
[0072]
As shown in FIG. 8, in this embodiment, first, iron-based sintering powder 44, nickel powder 11 and phosphorus powder 12 are prepared, and after nickel powder 11 is refined, phosphorus powder 12 is mixed, A powder 10 for sintering is obtained.
[0073]
Next, the die 31 and the punches 32 and 33 described with reference to FIG. 1 are filled with the iron-based sintering powder 44 and the nickel-phosphorus sintering powder 10, and in this state, discharge plasma sintering is performed. To do. At this time, at the boundary portion between the iron-based sintering powder 44 and the nickel-phosphorous sintering powder 10, the powders are mixed and moved from the position away from the base material side to the base material side. While the nickel-phosphorous sintering powder 10 decreases, the iron-based sintering powder 44 increases.
[0074]
As a result, the original shape 40 of the cavity forming mold 4 is formed in which the base material 41 made of an iron-based sintered body and the tip portion 42 made of the nickel-phosphorous sintered body 15 are integrated by sintering. Here, at the boundary portion between the base material 41 and the sintered body 15, the nickel-phosphorus component decreases from the position away from the base material 41 toward the base material 41, and the inclined joint structure increases the iron-based component. Become.
[0075]
Next, the original 40 is subjected to heat treatment.
[0076]
Next, a machining process is performed. In this machining step, first, the outer diameter of the original shape 40 is processed using a grindstone so that the shape of the original shape 40 is close to the shape of the cavity forming die 4. Next, rough shape processing is performed on the tip portion 42 made of the nickel-phosphorus sintered body 15 in the original shape 40 by diamond cutting to form a cavity forming surface 44. Thereafter, the cavity forming die 4 is finished by finishing the cavity forming surface 44 of the tip portion 42 of the original shape 40 by diamond bit cutting.
[0077]
As described above, even in this embodiment, a portion made of nickel-phosphorus can be formed at a place where diamond bite cutting is performed by spark plasma sintering without performing time-consuming electroless plating, thereby reducing manufacturing costs. It is possible to obtain the same effects as those of the first embodiment, for example, and the manufacturing period of the mold can be greatly shortened. Further, since the base material 41 made of steel and the nickel-phosphorus sintered body 15 (tip portion 42) have an inclined joint structure, the joining strength between the base material 41 and the sintered body 15 is high.
[0078]
[Other embodiments]
FIG. 9 and FIG. 10 are process diagrams respectively showing a method for producing a cavity-forming mold for resin molding according to another embodiment of the present invention.
[0079]
  Any of the above embodiments 1, 2, 3, 4And reference examplesIn FIG. 9, after forming the original shape 40, the concave portion that becomes the cavity forming surface 44 is formed by the first diamond cutting process. However, as shown in FIG. 9, the most distal portion 45 of the cavity forming mold 4 is formed. When the sintered body 15 is formed by discharge plasma sintering, irregularities are formed on the press surface of the punch 32 (or punch 33) used for the discharge plasma sintering, and the irregularities are transferred to the sintered body 15. By doing so, a recessed portion that becomes the cavity forming surface 44 may be formed in the sintered body 15.
[0080]
The other steps are substantially the same as those of the first embodiment described with reference to FIG. 4 and thus will not be described. In this embodiment, when the sintered body 15 is formed, the cavity forming surface 44 and Therefore, it is not necessary to form a concave portion that becomes the cavity forming surface 44 by the diamond bit cutting process on the original shape 40, and after the outer diameter processing, the diamond bit cutting process is performed to finish the cavity forming surface 44 as it is. Can be done. Therefore, since the number of manufacturing steps can be reduced, the manufacturing cost can be reduced.
[0081]
Further, such a configuration that the unevenness of the punch 32 (or the punch 33) is transferred to the sintered body may be applied to the fourth embodiment described with reference to FIG. 7 as shown in FIG. Good. That is, also in the fourth embodiment, after forming the original shape 40 by the discharge plasma sintering method, the concave portion that becomes the cavity forming surface 44 is formed by the first diamond cutting process. However, as shown in FIG. When the tip portion 42 of the mold 4 is formed by discharge plasma sintering, irregularities are formed on the press surface of the punch 32 (or punch 33) used for the discharge plasma sintering, and the irregularities are formed in the sintered body 15. The concave portion that becomes the cavity forming surface 44 may be formed in the sintered body 15 by transferring to the sintered body 15.
[0082]
The other steps are substantially the same as those of the fourth embodiment described with reference to FIG. 7 and thus will not be described. In this embodiment, the cavity forming surface 44 and Therefore, it is not necessary to form a concave portion that becomes the cavity forming surface 44 by the diamond bit cutting process on the original shape 40, and after the outer diameter processing, the diamond bit cutting process is performed to finish the cavity forming surface 44 as it is. Can be done. Therefore, since the number of manufacturing steps can be reduced, the manufacturing cost can be reduced.
[0083]
【The invention's effect】
As described above, in the present invention, the cavity forming surface such as the cavity forming surface of the cavity forming mold is not formed by electroless plating but by a pulsed current pressure sintering method for sintering powder containing nickel-phosphorus. Such a sintered portion is machined. Therefore, a nickel-phosphorus portion deep enough to be machined can be formed in a short time without performing electroless plating, thereby reducing the manufacturing cost and reducing the mold production period. Can be shortened. Also, unlike plating treatment, the pulsed current pressure sintering method is performed under pressure, so large bubbles do not enter the sintered body, and peeling or distortion occurs in the plating layer when heat treatment is performed. The yield is also improved. Furthermore, unlike electroless plating, condition management is easy and the material of the base material is not limited. Therefore, the manufacturing cost of the cavity forming mold can be reduced, and the yield can be improved.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing the principle of a discharge plasma sintering method.
FIG. 2 is an explanatory view showing a configuration example of a cavity forming mold that constitutes a cavity in a resin molding machine.
FIGS. 3A and 3B are a side view and a cross-sectional view taken along the line AA ′ of FIG.
FIG. 4 is a process diagram showing a method for manufacturing a cavity-forming mold for resin molding according to Embodiment 1 of the present invention.
FIG. 5 is a process diagram showing a method for manufacturing a cavity-forming mold for resin molding according to Embodiment 2 of the present invention.
FIG. 6 is a process diagram showing a method for manufacturing a cavity-forming mold for resin molding according to Embodiment 3 of the present invention.
FIG. 7 is a process diagram showing a method for manufacturing a cavity-forming mold for resin molding according to Embodiment 4 of the present invention.
[Fig. 8] of the present inventionReference exampleIt is process drawing which shows the manufacturing method of the cavity formation metal mold | die for resin molding which concerns on this.
FIG. 9 is a process diagram showing a method for manufacturing a cavity-forming mold for resin molding according to another embodiment of the present invention.
FIG. 10 is a process diagram showing a method for producing a cavity-forming mold for resin molding according to another embodiment of the present invention.
FIG. 11 is a process diagram showing a conventional method for producing a cavity-forming mold for resin molding.
FIG. 12 is an explanatory view showing a state of electroless nickel-phosphorus plating in a manufacturing process of a conventional cavity forming mold for resin molding.
[Explanation of symbols]
1 Resin molding machine
2 cavity
4 Cavity forming mold
5 Sprue
6 runners
7 Gate
8 Ejector pin
10 Nickel-phosphorous sintering powder
11 Nickel powder
12 Phosphorus powder
15 Sintered body
30 Plasma discharge sintering equipment
41 Base material
42 Tip
44 Cavity forming surface
45 Cutting edge
44 Sintering powder consisting of the same components as the base material
46 The base of the tip
410 Base material blank
411, 412 channel
413 annular channel

Claims (8)

An original shape forming step for forming an original shape for forming a cavity forming die for resin molding, and at least a portion of the original shape to be a cavity forming surface of the cavity forming die is machined to form the cavity forming die. In a manufacturing method of a cavity forming mold for resin molding having a machining process to finish
In the original shape forming step, after forming a sintered body of nickel-phosphorus by a pulsed current pressure sintering method for a sintering powder containing nickel-phosphorus, a base material made of the sintered body and a steel material of a predetermined shape; The sintering powder containing nickel-phosphorus is disposed between the two, and in this state, the original shape is formed by joining the sintered body and the base material by the pulse current pressure sintering method,
In the machining step, the machining is performed on at least a portion of the sintered body that is to become the cavity forming surface. In claim 1,
In the original shape forming step, when joining the sintered body of nickel-phosphorous and the base material, a powder for sintering containing the nickel-phosphorous disposed between the sintered body and the base material; A method for producing a cavity-forming mold, characterized in that iron-based sintering powder is disposed between the base material. An original shape forming step for forming an original shape for forming a cavity forming die for resin molding, and at least a portion of the original shape to be a cavity forming surface of the cavity forming die is machined to form the cavity forming die. In a manufacturing method of a cavity forming mold for resin molding having a machining process to finish
In the original shape forming step, a powder for sintering containing nickel-phosphorus is disposed at a position adjacent to a base material made of a steel material having a predetermined shape, and in this state, a pulsed current pressure sintering method is applied to the base material. Forming the original shape to which a sintered body of nickel-phosphorus is bonded,
In the machining step, the machining is performed on at least a portion of the sintered body that is to become the cavity forming surface. In claim 3,
In the original shape forming step, an iron-based sintering powder is disposed between the base material and the sintering powder containing nickel-phosphorus, and a method for manufacturing a cavity-forming mold. In any one of Claims 1 thru | or 4,
In the original shape forming step, when the nickel-phosphorus sintered body is formed by a pulse current pressure sintering method, a predetermined unevenness is formed on the press surface of the punch that is in contact with a portion to be the cavity forming surface in the sintered body. The manufacturing method of a cavity forming mold is characterized in that the unevenness of the punch is transferred to the sintered body. In any one of Claims 1 thru | or 5,
The method for producing a cavity-forming mold, wherein the pulsed current pressure sintering method is any one of a discharge plasma sintering method, a discharge sintering method, and a plasma activated sintering method . In any one of Claims 1 thru | or 6,
In the machining step, the nickel-phosphorus sintered body is cut with a diamond cutting tool.   A cavity-forming mold manufactured by the method defined in any one of claims 1 to 7.

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