JP2007098714A - Resin molding device, method for manufacturing resin molded object and resin molded object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To mold a resin molded object requiring a through hole passing through a face and a back or a space between both sides etc. without generating a weldline. <P>SOLUTION: The resin molding device is equipped with a molding die for forming a cavity which forms the external shape of a molded object, a core etc. moving mechanism which makes the cavity coincide with the shape of a target molded object by introducing a core etc. for forming the through hole in the molded object into the cavity passing through a hole of the molding die, a melted resin injection device for injecting a melted resin into the cavity and a control device. In addition, the molding die has a fitting recessed part which fits into the apex of the core etc. after the cavity of such a shape as to coincide with the shape of the molded object is formed by the introduction of the core etc. moving mechanism. Further, the control device enables the injection of the melted resin into the cavity in a state that the core etc. is half-introduced in the cavity, then moves the core etc. fully introduced into the cavity after the injection, and compresses the melted resin. Further, even after the compression, the control device enables the introduction of the core etc. until the apex of the core etc. fits into the fitting recessed part and thereby, achieves the completion of work to open the through hole. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for molding a resin molded product that requires a through-hole penetrating the front and back surfaces or between both side surfaces.

  In recent years, environmental problems are regarded as a problem, and the treatment of petroleum-based resins widely used for electrical appliances has a large environmental load and causes various problems. In order to solve this problem, attempts to use a non-petroleum resin derived from a living organism called a biodegradable resin have recently been widespread. Unlike biodegradable resins, this biodegradable resin is less likely to generate carbon oxides and nitrogen oxides even when incinerated. Have the benefits.

  On the other hand, biodegradable resins are harder and more brittle than petroleum-based resins, and have a weak point in that mechanical properties represented by heat distortion temperature decrease when the temperature rises. Therefore, as a composite technique, a necessary amount of an inorganic filler (for example, talc, calcium carbonate, etc.) is added to improve heat resistance. However, when a biodegradable resin whose heat distortion temperature is raised by such a method is molded using an injection molding machine, the part called the resin fusion part (weld line) where the strength is significantly reduced at the position opposite to the resin injection port There is a problem that occurs.

  For example, a square decorative frame 2 is attached around a central circular operation dial 1 as shown in FIG. 7 on the front surface of a circuit breaker attached to a control center that opens and closes a low-voltage motor. As shown in FIG. 8, the decorative frame 2 has a large-diameter circular hole 3 for passing the operation dial 1 in the center of a rectangular plate and a small-diameter screw insertion hole 4 for passing a fixing screw in the corner. It has a shape that penetrates.

  The decorative frame 2 is formed by injecting resin into an injection mold 6 as shown in FIG. 9, for example. This injection mold 6 is a combination of an upper mold 7 and a lower mold 8, and the figure is a cross-sectional view of the injection mold 6 in a separated state. The upper mold 7 has a columnar core 10 protruding downward in the center, and an upper mold recess 11 having the same shape as the planar shape of the decorative frame 2 is formed around the upper mold 7. A sprue 12 serving as a passage for molten resin is provided in the center of the core 10 so as to penetrate vertically, a runner 13 is formed horizontally from the lower end, and a gate 15 that opens to the cavity 14 is provided at the tip. ing.

  On the other hand, the lower mold 8 is formed with a rectangular lower mold recess 16 that matches the planar outer shape of the decorative frame 2. The depth of the lower mold recess 16 is adjusted so that the sum of the depth of the upper mold recess 11 matches the height of the core 10. In addition, projecting pins 17 for forming the screw insertion holes 4 project from the two corners of the lower mold recess 16. The gate 15 is opened at a position toward the two protruding pins 17. When the upper mold 7 and the lower mold 8 are clamped, a cavity 14 for forming the decorative frame 2 having the shape shown in FIG. 8 is formed therebetween.

  The molding is performed by clamping the upper mold 7 and the lower mold 8 and injecting molten molding resin into the cavity 14 through the sprue 12, the runner 13, and the gate 15. FIG. 10 shows the flow of the molten resin injected into the cavity 14.

  The molten resin injected from the two gates 15 a and 15 b branches into two hands and flows along the periphery of the core 10. And it joins in the A1 and A2 part of a figure, and is cooled and solidified. The merged portion of A1 and A2 is called a weld line. Also around the two projecting pins 17, the molten resin is small and bifurcated, merges at B1 and B2 portions of the flowchart, and is cooled and solidified. Therefore, weld lines are also formed in the B1 and B2 portions.

  Such a weld line is formed at a portion where the resin whose temperature has decreased by flowing in the cavity joins. In the weld line, the molding resins are not completely adhered and solidified, and a minute gap is generated. For this reason, the bond strength of the resin is weak and cracking is likely to occur with a slight stress. It is known that this weld line is likely to occur when a protrusion for forming a through hole is formed in a cavity such as a core or a protruding pin on the forward extension line of the gate as in the above example. It has been.

In order to form a through hole in the formed product, a protrusion such as a core or a protruding pin must be provided in the cavity. Various devices have been proposed in the past that do not cause a weld line even if such protrusions exist (see, for example, Patent Documents 1 and 2). However, it is hard to say that all of them have achieved sufficient results.
Japanese Patent Laid-Open No. 2003-340889 Japanese Patent Application No. 2004-109975

  The present invention has been made in view of such circumstances, and its object is to provide a technique for molding a resin molded product that requires a through-hole penetrating the front and back surfaces or between both side surfaces without causing a weld line. There is.

  The invention according to claim 1 for solving the above problem is a resin molding apparatus (20) for molding a resin molded product (2) that requires through holes (3, 4) penetrating the front and back sides or between both side surfaces. The mold (25) for forming the cavity (14) for forming the outer shape of the molded product, the core (10) for forming the through hole, the projecting pin (17), or both (hereinafter referred to as the following) The core or the like is provided at the tip, and the core or the like is inserted into the cavity through the holes (44, 45) formed in the molding die so that the cavity has the shape of a molded product having a desired through hole when the penetration is completed. The core moving mechanism (26), the molten resin injection device (22) for injecting the molten resin into the cavity through the resin injection hole (56) provided in the molding die, and the control device ( 23), and The mold has a fitting recess (53, 54) that fits with the tip of the core or the like that further moves in after the moving mechanism such as the core enters and a cavity having a shape that matches the shape of the molded product is formed. And the control device causes the molten resin injection device to inject the molten resin in a state where the core or the like is semi-penetrated through the hole formed in the mold, and after the injection, the core or the like is moved by a moving mechanism such as the core. The molten resin injected and moved into the molding die is compressed, and after the compression, the penetration movement is continued until the tip of the core or the like is fitted in the fitting recess of the molding die, thereby completing the through hole. It is the resin molding apparatus characterized by controlling so that an intrusion movement may be stopped after.

Since the resin molding apparatus having such a structure injects the molten resin in a state where the core or the like is half-penetrated into the cavity, that is, in a state where the through-hole is not completed as it is, a branched flow of the injected molten resin hardly occurs. It has the advantage that lines are less likely to occur.
Further, after the molten resin is injected, the core or the like is further moved into the cavity to complete the through hole. In the process of completing the through hole, the volume of the cavity is reduced and the injected molten resin is compressed. For this reason, even if a weld line occurs during the molten resin injection, the minute gap generated in the weld line due to the volume reduction of the molten resin due to compression is crushed and disappears. Therefore, there is an effect that a resin molded product having a through hole can be molded firmly without causing a weld line.

  The invention according to claim 2 is the resin molding apparatus according to claim 1, wherein each tip portion of the core or the like is inclined so that a substantially central portion of each tip protrudes from the outer edge portion. It is the resin molding apparatus characterized.

  Immediately before the tip of the core or the like is fitted into the fitting recess, the molten resin existing in front of the tip of the core or the like flows out into the cavity. When the tip of the core or the like has a protruding shape, the molten resin flows out smoothly into the cavity, so the molten resin is compressed immediately before the through hole is formed in the molded product and the through hole is formed. There exists an effect that formation is performed smoothly.

Further, the invention according to claim 3 is the resin molding apparatus according to claim 1, wherein each tip portion of the core or the like is a groove that gradually becomes deeper as it goes to the outer edge between the substantially central portion of each tip and the outer edge. A resin molding apparatus in which one or several (70) are formed.
In such a configuration, the same effect as that of the second aspect of the invention can be obtained.

  According to a fourth aspect of the present invention, there is provided the resin molding apparatus according to the first aspect, wherein the molding die includes three upper molds (29), an intermediate mold (30), and a lower mold (31). It is composed of a mold, and a hole for allowing the core and the like to enter is provided in the lower mold, and a cavity for forming the outer shape of the molded product is formed at the mating portion of the intermediate mold and the lower mold, and is fitted to the tip of the core and the like. The fitting recess to be mated is a resin molding apparatus characterized in that a through hole (50, 51) having the same shape is provided in the intermediate mold and the surface of the upper mold facing the through hole is flattened. is there.

  If the molding die is configured in this way, the resin residue remaining in the fitting recess after molding can be easily removed.

According to a fifth aspect of the present invention, in the resin molding apparatus according to any one of the first to fourth aspects, the molding die is provided with a pressure sensor (63) for detecting the pressure of the molten resin injected into the cavity. The mounting and control device starts intrusion movement into the molding die of the core or the like by the core etc. moving mechanism when the pressure detected by the pressure sensor reaches a predetermined threshold value. Device.
By detecting the pressure of the molten resin in this way, it is possible to accurately grasp the timing when the core or the like starts to enter and move into the molding die.

  According to a sixth aspect of the present invention, in the resin molding apparatus according to any one of the first to fourth aspects, the molding die further includes a temperature sensor (64) for detecting the temperature of the molten resin injected into the cavity. The mounting and control device starts intrusion movement into the molding die of the core or the like by the movement mechanism of the core or the like when the temperature detected by the temperature sensor reaches a predetermined threshold value. Device.

  By detecting the temperature of the molten resin in this way, it is possible to accurately grasp the time when the core or the like starts to enter and move into the molding die.

The invention according to claim 7 is a resin molded product manufacturing method for molding a resin molded product that requires a through-hole penetrating the front and back sides or between both side surfaces, and the molded product formed in the molding die. A molten resin injecting step for injecting a molten resin into the cavity in a state where a core or the like for forming a through hole is half-penetrated through a hole provided in a molding die into a cavity for forming an outer shape, and injection of the molten resin When the pressure in the cavity reaches a predetermined threshold, the molten resin compression process compresses the molten resin injected by moving the core into the cavity and the cross-sectional shape of the core in the molding die. After completion of the molten resin compression process, the core and the like are further moved in until the tip part is fitted into the fitting recess to complete the through hole required by the resin molded product. Through-hole And forming step, a resin molded article manufacturing method characterized by having a.
Such a resin molded product manufacturing method has the same effect as that of the first aspect of the invention.

The invention according to claim 8 is the method of manufacturing a resin molded product according to claim 7, wherein in the molten resin compression step, the temperature of the molten resin in the cavity is a predetermined value instead of the pressure in the cavity. The resin molded product manufacturing method is characterized in that when the threshold value is reached, the core or the like is moved into the cavity.
Such a resin molded product manufacturing method also has the same effect as that of the first aspect of the invention.

The invention according to claim 9 is a resin molded product characterized in that a molten resin of biodegradable resin is used as the molten resin and is molded by the resin molded product manufacturing method according to claim 7 or 8. is there.
A biodegradable resin tends to generate a weld line. However, a biodegradable resin molded product manufactured by such a method does not generate a weld line, and therefore has a strong and strong advantage even in a shape having a through hole.

  Hereinafter, for one embodiment of the resin molding apparatus according to the present invention, a rectangular decorative frame having a large-diameter circular hole 3 at the center and a through-hole of a small-diameter screw insertion hole 4 at the corner shown in FIGS. The case where (resin molded product) 2 is formed will be described as an example. FIG. 1 shows an apparatus configuration of the resin molding apparatus 20. The resin molding apparatus 20 of the present embodiment includes a molding die apparatus 21, a molten resin injection apparatus 22, and a control apparatus 23.

  Among these, the molding die device 21 includes a molding die 25, a core moving mechanism 26, and a mold opening / closing mechanism 27. The molding die 25 is a die for forming a cavity (mold inner space) 14 that determines the outer shape of the target resin molded product 2. From the top, the upper die 29, the intermediate die 30, and the lower die 31 are formed. It consists of three molds. The upper mold 29 is fixed to the upper fixing frame 33 of the mold opening / closing mechanism 27 through a fixed side mounting plate 32. The lower mold 31 is fixed to a slide frame 37 of the mold opening / closing mechanism 27 via a spacer block 35 and a receiving plate 36. The slide frame 37 of the mold opening / closing mechanism 27 is configured to be movable up and down along the guide column 38 by a hydraulic drive mechanism (not shown), and is configured to move the lower mold 31 up and down by moving the slide frame 37 up and down. It has become.

  The intermediate mold 30 is located between the upper mold 29 and the lower mold 31. FIG. 1 shows a state in which the slide frame 37 is raised and three molds are clamped. The intermediate mold 30 is attached to the upper mold 29 so as to be suspended. When the slide frame 37 is lowered from the state of FIG. 1, the intermediate mold 30 is lowered while being placed on the lower mold 31, and the parting 41 between the upper mold 29 and the intermediate mold 30 is opened. When the parting 41 is opened by a certain distance, the intermediate mold 30 is suspended from the upper mold 29, and the intermediate mold 30 is not lowered any further. Instead, the parting 42 between the intermediate mold 30 and the lower mold 31 is opened, and the lower mold 31 is lowered. When the slide frame 37 is raised, the three molds are clamped in a state as shown in FIG. In the process of raising the lower mold 31, the intermediate mold 30 is positioned at a predetermined position of the lower mold 31. For this purpose, a guide mechanism (not shown) by fitting is provided.

  The cavity 14 that determines the outer shape of the rectangular resin molded product 2 shown in FIG. 8 has a cross section equal to the square of the resin molded product 2 at the mating portion of the intermediate mold 30 and the lower mold 31 and has a depth of It is formed by providing concave portions 42 and 43 whose total is equal to the thickness of the resin molded product 2. Further, the lower mold 31 has a through hole 44 through which the core 10 for providing the large-diameter circular hole 3 at the center of the resin molded product 2 and a protruding pin 17 for providing the small-diameter screw insertion hole 4 at the corner. A through-hole 45 is provided through.

  Both the core 10 and the projecting pin 17 are fixed to a support body 47, and the support body 47 is supported by a hydraulic cylinder 48 fixed to a receiving plate 36 so as to be vertically movable. Thus, the core 10, the protruding pin 17, the support body 47, and the hydraulic cylinder 48 constitute the core moving mechanism 26.

  When the support 47 is raised by the hydraulic cylinder 48, the core 10 and the projecting pin 17 inserted into the through holes 44 and 45 opened in the lower mold 31 enter the cavity 14. And when those front-end | tips reach the bottom of the recessed part 42 provided in the intermediate metal mold | die 30, the shape of the cavity 14 becomes equal to the shape of the target resin molded product 2 shown in FIG.

  In the molding die 25 of the present embodiment, the core 10 and the projecting pin 17 are connected to the core 10 and the corresponding portion of the intermediate die 30 so that the intrusion can continue even after reaching the bottom of the concave portion 42 of the intermediate die 30. Through holes 50 and 51 having the same cross-sectional shape as the protruding pin 17 are provided. The lower surface of the upper mold 29 facing the through holes 50 and 51 is formed flat. The space formed by the through holes 50 and 51 provided in the intermediate mold 30 and the flat portion of the upper mold 29 facing the through holes 50 and 51 is fitted with the respective distal ends of the core 10 and the projecting pin 17. It functions as the recesses 53 and 54. In this way, the tip portions of the core 10 and the projecting pin 17 are configured so as to finally reach the upper mold 29 and the parting 41 of the intermediate mold 30.

  The molten resin is injected into the cavity 14 through a resin inflow path that connects the sprue 56 provided in the upper mold 29, the runner 57 provided in the intermediate mold 30, and the gate 58 opening in the cavity 14. An opening 60 is provided in the fixed side mounting plate 32 facing the inlet of the sprue 56, and the nozzle 61 of the molten resin injection device 22 is brought into contact with the inlet of the sprue 56 through the opening 60 to perform resin injection.

  The control device 23 is for controlling the operation of the resin molding device 20 by issuing command signals such as operation start, stop, and moving direction to each drive device (not shown) that drives each movable part of the resin molding device 20. is there. A pressure sensor 63 and a temperature sensor 64 for detecting the pressure and temperature of the molten resin injected into the cavity 14 are embedded in the upper mold 29, and detection values of these sensors are input to the control device 23. ing. The tip of the protruding pin 17 is formed at the same height as the tip of the core 10.

  Next, the molding method of the resin molded product 2 having two types of through holes, the circular hole 3 and the screw insertion hole 4 shown in FIG. The control flow and the situation in the cavity 14 in the molding process will be described with reference to FIG. In the first step S <b> 1 of the flow shown in FIG. 2, the control device 23 causes the mold 25 to be clamped. The mold clamping is performed by instructing a hydraulic drive mechanism (not shown) of the mold opening / closing mechanism 27 to raise the slide frame 37.

  In the subsequent step S2, the tips of the core 10 and the protruding pin 17 are raised to a predetermined position when the molten resin is injected into the cavity 14. Positioning of the core or the like is performed by instructing a control device (not shown) provided in the core or the like moving mechanism 26 to drive the hydraulic cylinder 48. FIG. 3 (1) shows the situation in the cavity 14 in a state where the core 10 and the tip of the protruding pin 17 are positioned by this instruction. The core 10 and the projecting pin 17 are positioned so that their tips are positioned slightly before being fitted into the through holes 50 and 51 (fitting recesses 53 and 54) provided in the intermediate mold 30. This positioning is performed using a core movement mechanism position detection sensor (not shown) attached to the core movement mechanism 26.

  If the core moving mechanism 26 is thus positioned, in the next step S3, the molten resin injection device 22 is instructed to inject the molten resin. The molten resin is injected from the molten resin injection device 22 into the cavity 14 through the nozzle 61, the sprue 56, the runner 57, and the gate 58. In the present embodiment, the injection is stopped in a state where about 95% of the space including the cavity 14 and the fitting recesses 53 and 54 is filled with the molten resin. That is, the filling is stopped in a state where about 5% of the unfilled space remains.

  Filling the molten resin to leave about 5% of the unfilled space is also possible by measuring the amount of molten resin injected by the molten resin injection device 22, but in this embodiment, the molten resin in the cavity 14 is filled. Judge by pressure. The pressure of the molten resin in the cavity 14 is detected by the pressure sensor 63 described above, and the value is input to the control device 23. The control device 23 checks the detection value of the pressure sensor 63 in step S4, and when the detection value becomes equal to or greater than a predetermined threshold value, the control device 23 proceeds to step S5 and stops the injection of the molten resin. The detected value of the pressure sensor 63 when about 5% of the unfilled space remains is obtained in advance through experiments or the like. (2) of FIG. 3 shows a state in the cavity 14 in a state where the injection of the molten resin 72 is finished while leaving an unfilled space of about 5%.

  When the injection is finished, in the following step S6, the core moving mechanism 26 is instructed to pass through holes 50 and 51 (fitting recesses 53 and 54) in which the tips of the core 10 and the protruding pin 17 are provided in the intermediate mold 30. The core 10 and the protruding pin 17 are instructed to move upward until they are fitted. When the core 10 and the projecting pin 17 start to move upward according to the instruction, the volume of the space including the cavity 14 and the fitting recesses 53 and 54 decreases. Therefore, the unfilled space is crushed by pressure and the entire space is filled with the molten resin. It becomes the state. This state is shown in (3) of FIG.

  Even after the entire space is filled with the molten resin, the core 10 and the projecting pin 17 continue to move upward, and accordingly, the volume of the space combining the cavity 14 and the fitting recesses 53 and 54 further decreases. To do. As a result, the molten resin filling the cavity 14 and the fitting recesses 53 and 54 is compressed and its volume is reduced. This compression continues until immediately before the tips of the core 10 and the protruding pin 17 are fitted into the through holes 50 and 51 (fitting recesses 53 and 54) provided in the intermediate mold 30.

  When the core 10 and the tip of the projecting pin 17 are in a state of being slightly fitted into the through holes 50 and 51 (fitting recesses 53 and 54) (see (4) in FIG. 3), the volume of the cavity 14 is more than that. Therefore, the compression of the molten resin in the cavity 14 is stopped. The upward movement of the core 10 and the projecting pin 17 is stopped in a state where the tips are slightly fitted in the through holes 50 and 51 (fitting recesses 53 and 54). That the tip is slightly fitted in the through holes 50 and 51 (fitting recesses 53 and 54) is determined by the control device of the core movement mechanism 26 based on the detection value of the core movement mechanism position detection sensor. To stop the ascending movement.

  If the upward movement is stopped, it waits for the molten resin to cool and solidify in that state (step S7). After cooling and solidification, the core moving mechanism 26 is lowered (step S8), then the slide frame 37 is lowered (step S9), the mold is opened, and the molded product is taken out. Thereby, the intended resin molded product 2 of FIG. 8 is completed.

  The characteristic of the molding method of the resin molded product according to this embodiment described above is that the formation of the through-holes required for the molded product and the compression of the injected molten resin are executed simultaneously. In the conventional molding method described in “Background Art”, the molten resin is injected in a state where a core and a projecting pin for providing a through hole in the cavity are installed in advance. For this reason, there has been a problem in that the melted resin is bifurcated and flows around the core and the projecting pin, and a weld line is generated at the place where the branched flows are combined.

  On the other hand, in the molding method according to the present embodiment, the molten resin is injected in a state where the core and the projecting pin are half-penetrated into the cavity, that is, in a state where the through hole is not completed as it is. Since the core and the protruding pin are not completely intruded into the cavity, there is an advantage that the welded line is less likely to be generated because the injected molten resin is less likely to branch.

  Further, after the molten resin is injected, the core and the projecting pin are further moved into the cavity to complete the through hole. In the process of completing the through hole (the process of moving the core and the projecting pin further into the cavity), the volume of the cavity is reduced, so that the injected molten resin is compressed and the volume is reduced. For this reason, even if a weld line occurs during the injection of the molten resin, the minute gap generated in the weld line due to the volume reduction of the molten resin due to the compression is crushed and disappears. Therefore, according to the molding method of the present embodiment, it is possible to mold a strong resin molded product having a through hole without a weld line. This is particularly effective when a resin molded product having a through-hole is formed using a biodegradable resin (for example, polylactic acid resin) that easily generates a weld line.

(Modified embodiment)
The resin molding apparatus 20 and the molding method described above may be modified as follows.
(1) In the above embodiment, the state in which the molten resin is injected while leaving about 5% of the unfilled space in the cavity 14 is determined based on the detection value of the pressure sensor 64. Alternatively, the determination may be made based on the temperature of the molten resin in the cavity 14. Since the temperature sensor 64 for detecting the temperature of the molten resin injected into the cavity 14 is embedded in the upper mold 29 as described above, when the detected value reaches a predetermined threshold value. Stop pouring molten resin. The detection value of the temperature sensor 64 when about 5% of the unfilled space remains is obtained beforehand by experiments or the like.
(2) In the above embodiment, as shown in FIGS. 1 and 3, the tips of the core 10 and the projecting pin 17 are flat, but they may be formed so that the tips project from the periphery. FIG. 4 is an example in which the tip is projected in a substantially conical shape. The slope of the protrusion may be a gentle slope. FIG. 5 shows an example in which a gently inclined groove 70 is provided in a cross shape with the tip kept flat, (1) in FIG. 5 is a plan view of the tip, and (2) in FIG. 5 is (1) in FIG. It is sectional drawing along the AA in FIG.

  6 (1) shows the situation in which the molten resin is compressed using the core 10 and the projecting pin 17 with the tip protruding in this manner, and FIG. 6 (2) shows the cavity after the compression is finished. 14 shows the situation within 14. Immediately before the tips of the core 10 and the projecting pin 17 are fitted into the fitting recesses 53 and 54 of the intermediate mold 30 (see (1) in FIG. 6), the volume of the fitting recesses 53 and 54 decreases. The molten resin filling the inside flows out into the cavity 14 as shown by the arrows in the figure. Since the tips of the core 10 and the projecting pin 17 are projected, the molten resin flows out smoothly into the cavity 14. Therefore, there is an effect that the molded resin is compressed immediately before the through holes 44 and 45 of FIG. 8 are formed and the through holes 44 and 45 are smoothly formed in the molded product.

It is an apparatus structure of the resin molding apparatus 20 which is one Embodiment of this invention. It is the control flow which the control apparatus 23 performs. It is a figure explaining the condition in the cavity in the shaping | molding process of a resin molded product. This is an example in which the tips of the core 10 and the projecting pin 17 are projected in a substantially conical shape. This is an example in which a gently inclined groove 70 is provided in a cross shape while the tips of the core 10 and the protruding pin 17 are kept flat. It is a figure explaining the condition in the cavity in the process of compressing molten resin using the core 10 and the protrusion pin 17 of the shape which made the front-end | tip protrude. It is an example of a square resin molded product (decorative frame) 2 attached around a circular operation dial 1. It is an example of the shape of the resin molded product (decorative frame) which has a through-hole. It is an example of the resin molding die concerning a prior art. It is a figure which shows the mode of the flow of the molten resin inject | poured in the cavity of the resin molding die of a prior art.

Explanation of symbols

  In the drawings, 2 is a resin molded product (decorative frame), 3 is a through hole, 10 is a core, 14 is a cavity, 17 is a protruding pin, 20 is a resin molding device, 22 is a molten resin injection device, and 23 is a control device. , 25 is a molding die, 26 is a moving mechanism such as a core, 29 is an upper die, 30 is an intermediate die, 31 is a lower die, 44 and 45 are holes, 53 and 54 are fitting recesses, and 56 is a resin injection Holes (sprues) 50 and 51 are through holes, 63 is a pressure sensor, 64 is a temperature sensor, and 70 is a groove.

Claims (9)

A resin molding apparatus (20) for molding a resin molded product (2) that requires through holes (3, 4) penetrating the front and back surfaces or between both side surfaces,
A mold (25) for forming a cavity (14) for shaping the outer shape of the molded article;
A hole (44, 45) provided with a core (10) or a projecting pin (17) or both (hereinafter referred to as a core or the like) for forming the through-hole at the tip, and the core or the like opened in the molding die. ) And the like, the core moving mechanism (26) configured to enter the cavity through the shape of the molded article having the desired through hole when the penetration is completed,
A molten resin injection device (22) for injecting molten resin into the cavity through a resin injection hole (56) provided in the molding die;
A control device (23) for overall control of the resin molding device,
The molding die has a fitting recess (53) that fits with a tip portion of the core or the like that moves in even after the moving mechanism such as the core enters and a cavity having a shape that matches the shape of the molded product is formed. 54)
The control device causes the molten resin injection device to inject molten resin in a state in which the core or the like is half-penetrated through the hole into the cavity formed in the molding die, and the core movement mechanism after the injection The core or the like is moved into the molding die to compress the injected molten resin, and after the compression, the core or the like is moved into the molding die until the leading end is fitted into the fitting recess. A resin molding apparatus characterized by controlling to stop the intrusion movement after the through hole is completed.   The resin molding apparatus according to claim 1, wherein each tip portion of the core or the like is inclined so that a substantially central portion of each tip protrudes from an outer edge portion.   2. The resin molding apparatus according to claim 1, wherein one or several grooves (70) that gradually become deeper toward the outer edge are formed between each of the front ends of the core and the like between a substantially central portion of each front end and the outer edge. The resin molding apparatus characterized by the above-mentioned.   2. The resin molding apparatus according to claim 1, wherein the molding die includes three molds of an upper mold (29), an intermediate mold (30), and a lower mold (31), and the core and the like are formed. A hole for intrusion is provided in the lower mold, and a cavity for forming the outer shape of the molded product is formed in a mating portion of the intermediate mold and the lower mold, and the fitting that fits with the tip of the core or the like The concave portion is formed by providing through holes (50, 51) having the same shape in the intermediate mold and flattening the surface of the upper mold facing the through holes. The resin molding apparatus according to any one of claims 1 to 4, wherein a pressure sensor (63) for detecting the pressure of the molten resin injected into the cavity is attached to the molding die,
The controller starts the intrusion movement of the core or the like into the molding die by the core or the like moving mechanism when the pressure detected by the pressure sensor reaches a predetermined threshold value. Resin molding equipment. The resin molding apparatus according to any one of claims 1 to 4, wherein a temperature sensor (64) for detecting a temperature of the molten resin injected into the cavity is attached to the molding die.
The resin is characterized in that the control device starts intrusion movement of the core or the like into the molding die by the core or the like moving mechanism when the temperature detected by the temperature sensor reaches a predetermined threshold value. Molding equipment. A resin molded product manufacturing method for molding a resin molded product that requires a through-hole penetrating between the front and back surfaces or both side surfaces,
A core or the like for forming the through hole is semi-penetrated through a hole provided in the molding die into a cavity for forming the outer shape of the molded product formed in the molding die, and in this state, molten resin is introduced into the cavity. Molten resin injection step of injecting
A molten resin compression step of compressing the injected molten resin by moving the core or the like into the cavity when the pressure in the cavity reaches a predetermined threshold value due to the injection of the molten resin;
A fitting recess having a shape equal to the cross-sectional shape of the core or the like is provided in the molding die, and the core or the like is further fitted into the fitting recess after the molten resin compression step. And a through hole forming step of completing the through hole required for the resin molded product by intrusion and movement.   8. The method of manufacturing a resin molded product according to claim 7, wherein in the molten resin compression step, the core or the like is removed when the temperature of the molten resin in the cavity reaches a predetermined threshold instead of the pressure in the cavity. A method for producing a resin molded product, wherein the resin is intruded and moved into the cavity. A resin molded product, wherein a molten resin of a biodegradable resin is used as the molten resin, and is molded by the resin molded product manufacturing method according to claim 7 or 8.

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