JP2008014686A - Pin with light conductor member and injection molding die provided with the pin with light conductor member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an ejector pin provided with a light conductor with a comparatively simple structure, attaining a small size and making the adjustment of the length of the ejector pin easy. <P>SOLUTION: The ejector pin provided with the light conductor comprises: a cylindrical hollow shaft part; a cylindrical spacer internally fixed with a heat resistant adhesive material being in contact with the hollow shaft; and an optical fiber bonded to the cylindrical spacer internally being in contact with the cylindrical spacer with the heat resistant adhesive material. The ejector pin constituted with the optical fiber, the cylindrical spacer and the tip face of the hollow shaft essentially in one same surface solves the problem. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light guide for a temperature sensor for guiding light to the temperature sensor. In particular, the present invention relates to a pin with a light guide for measuring the temperature of a resin in a cavity of a molding die.

  In recent years, in the injection molding method of molding a product by injecting and filling a resin into a cavity of a molding die, there is an increasing demand for shape accuracy and miniaturization of a molded part. Also, newly developed high-functional materials need to be controlled more precisely at high temperature and high pressure than before in order to exhibit their performance. In order to meet these requirements, so-called intelligentization is progressing, in which the temperature and pressure in the mold cavity during injection molding are measured and fed back to the molding conditions.

  Specifically, a sensor for measuring the resin pressure in the cavity of the mold and a sensor for measuring the resin temperature are provided, and such information is fed back to the molding machine.

  As a method for measuring the resin temperature in the mold cavity, there are a method of measuring indirectly by a thermocouple embedded in the mold, and a method of measuring directly from the infrared radiation of the resin. In this case, the infrared radiation emitted from the resin is often transmitted to the infrared detector using the optical fiber bundle as a light guide.

  FIG. 4 shows an infrared radiation light guide disclosed in Patent Document 1. The light guide also functions as an ejector pin provided in the mold. The ejector pin 100 is provided with a hollow portion 1 penetrating the inside. A diameter-enlarged portion 2 is provided at one end of the hollow portion 1 of the ejector pin 100 facing the cavity surface C of the mold, and a support sleeve 3 having a tapered hole is accommodated therein, and the support sleeve 3 is tapered. The sapphire cone 4 is accommodated.

  The large-diameter end of the sapphire cone 4 is arranged in substantially the same plane as the end portion of the ejector pin, and the small-diameter end is connected to a flexible bundle-like optical fiber 5 arranged in a cable shape in the hollow portion 1. The other end of the optical fiber 5 is provided with a light receiving portion and a calculating portion (not shown) for infrared radiation, and the calculating portion calculates the resin temperature in the mold from the infrared light incident on the light receiving portion.

  Here, FIG. 5 shows an ejector pin 200 having the function of an infrared radiation light guide studied by the applicant of the present invention in the process leading to the invention according to the application. In FIG. 5, the same reference numerals are used for parts common to FIG. 5A is a top view, FIG. 5B is a sectional view taken along the line aa ′, and FIG. 5C is a left side view. The ejector pin 200 has a hollow shaft shape in which a hollow section 1 having a circular cross section penetrating the inside is provided, and a single-line optical fiber 5 passes through the inside as a light guide, and the gap between the optical fiber 5 and the hollow shaft section 6 is between It is fixed with an epoxy adhesive 7.

JP 58-137721 A

The infrared radiation light guide disclosed in Patent Document 1 is a combination of an ejector pin and the function of the infrared radiation light guide, and the temperature of the infrared radiation light guide is not added to the mold. Enable measurement.
Further, since the sapphire cone 4 is supported by the support sleeve 3 with a tapered surface, and the support sleeve 3 is supported by a step with respect to the enlarged diameter portion 2 of the hollow portion 1, even if the resin pressure in the mold increases, the sapphire cone 4 does not deviate, and the molded product does not deteriorate in quality such as dents.

However, the ejector pin 100 is difficult to process because of its complicated structure, and it is difficult to produce an ejector pin with a small diameter. The ejector pin 100 having a large diameter cannot be used for molding small precision parts.
Although the length of an ejector pin changes with each metal mold | die, the said ejector pin 100 needs to manufacture after deciding a dimension previously on a structure. Therefore, it was difficult to prepare a semi-finished product in advance and deliver a pin whose length was adjusted according to the customer's order in a short delivery time.
Moreover, it becomes very expensive due to the complicated structure, and it is practically difficult to provide a plurality of ejector pins in one mold.

  The ejector pin 200 with an infrared radiation light guide studied by the applicant shown in FIG. 5 in the course of making the invention according to the application is simpler in structure and thinner than that disclosed in Patent Document 1. Ejector pins can be made and the price can be relatively low. Moreover, since the hollow shaft portion 6 has the same cross-sectional shape regardless of where it is cut, prepare a semi-finished product with the hollow shaft portion having the same long dimension in advance, and install an ejector pin whose length is adjusted according to the customer's order. Can be delivered with short delivery time.

  Here, ejector pins are often made of tool steel (SKD) with excellent hardness and corrosion resistance because they are repeatedly used in harsh environments exposed to corrosive gas generated from resin under high pressure during molding. Tool steel is difficult to drill due to its hardness, and it is difficult to provide a long hole with a small diameter. In the ejector pin 200 shown in FIG. 5, even if the hollow section 1 having a circular cross section has a small inner diameter, it becomes φ2 mm, and a gap as large as the radius of the optical fiber 5 is formed around the optical fiber 5 having a diameter of φ1 mm. It was necessary to fill the portion with epoxy resin 7.

  Therefore, in the ejector pin 200 shown in FIG. 5, the optical fiber 5 is displaced from the center of the hollow portion 1 while the epoxy resin 7 is hardened, so that the appearance as a product is not good and the measurement position accuracy is sometimes deteriorated. Further, as shown in FIG. 6, since the epoxy resin layer 7 is thick, voids 8 may be generated inside. When the hollow shaft portion 6 is cut at, for example, the bb ′ portion, there is a problem that the void 8 is exposed on the surface and a smooth surface cannot be obtained.

  Therefore, the present invention solves the problem of the ejector pin disclosed in Patent Document 1 and FIG. 5, positions the optical fiber at the center of the hollow shaft portion, prevents the formation of bubbles in the adhesive layer, and places the shaft portion at an arbitrary position. It is an object of the present invention to provide a light guide pin with a relatively simple structure that can be cut at a high speed. Here, the “pin” is used as a term including the above-described ejector pin, a core pin that does not have a protruding function of a molded product, and a pin for temperature measurement at a high temperature.

  A pin with a light guide according to the present invention includes a cylindrical hollow shaft portion, a tubular spacer inscribed in the hollow shaft portion and fixed by a heat resistant adhesive, and a heat resistant adhesive inscribed in the tubular spacer. It has a columnar light guide to be fixed, and the light guide, the tubular spacer, and the front end surface of the hollow shaft portion substantially form the same surface.

  Moreover, the pin with a light guide according to the present invention can use an optical fiber having a core and a clad layer as a light guide, and a material in which the thermal expansion coefficient of the tubular spacer is larger than the thermal expansion coefficient of the hollow shaft. It can be. Moreover, the pin with a light guide according to the present invention can be incorporated into a molding die.

According to the present invention, since the pin with a light guide is realized with a relatively simple structure, it is possible to make a pin with a small diameter, and there is an effect that it can be used for molding management of small precision parts.
Moreover, since the price can be made relatively low, it is possible to provide a plurality of pins with light guides in one mold, and there is an effect that enables more strict management of molding conditions.

Also, the hollow shaft part has the same cross-sectional shape regardless of where it is cut, so a long semi-finished product with a long hollow shaft part having the same dimensions is prepared in advance, and the length of the pin is adjusted according to the customer's order. This has the effect of enabling delivery with a short delivery time.
Further, the optical fiber is positioned at the center of the hollow shaft portion, and there is an effect of preventing the generation of bubbles in the adhesive layer.

An embodiment of the present invention will be described with reference to FIGS. Here, the same reference numerals are used for parts common to the prior art. 1A is a top view, FIG. 1B is a sectional view taken along the line aa ′, and FIG. 1C is a left side view. The ejector pin 300 has a cylindrical hollow shaft portion 6, and a flange portion 11 having a diameter larger than that of the hollow shaft portion 6 is provided at the lower end thereof. A lid member 13 is fixed to the lower surface of the flange portion 11. Since the part of the collar part 11 is not exposed to high temperature, the lid member 13 can be fixed to the collar part 11 by a known method such as screwing or bonding.
In the present embodiment, tool steel (SKD61) is used for the ejector pin main body portion constituted by the hollow shaft portion 6, the flange portion 11, and the lid member 13.

  The hollow shaft portion 6 is provided with a hollow portion 1 having a uniform circular cross section passing through the inside in the axial direction. The hollow portion 1 has a uniform cross section above the center in the length direction of the hollow shaft portion 6. A diameter-expanded portion 2 having a larger diameter is provided. In this specification, “the cross section is uniform” means that the cross-sectional shape of the portion is substantially the same.

  A stainless steel (SUS) tubular spacer 10 is fixed to the enlarged diameter portion 2 with an adhesive. Since the ejector pin 300 is cut at the portion of the tubular spacer 10, the ejector pin 300 is fixed to the enlarged diameter portion 2 by an adhesive over the entire axial length of the tubular spacer 10. Epoxy resin can be used as the adhesive, but since the ejector pins are exposed to high temperatures exceeding 300 ° C during molding, heat resistant adhesives such as alkali silicate adhesives that are heat resistant to temperatures above 500 ° C A material is preferred.

  A single-wire optical fiber 5 is inserted into the tubular spacer 10, and the surface of the optical fiber 5 is fixed to the inner surface of the tubular spacer 10 with an adhesive 14. A heat-resistant adhesive is also suitable for the bonding of this portion. The optical fiber 5 has a two-layer structure in which a cladding layer as a reflective layer is provided on the surface of the core so as to function as a light guide. The optical fiber 5 is made of silica glass, Ge (germanium) or P (phosphorus) is added to the core, and B (boron) or F (fluorine) is added to the cladding.

The optical fiber 5 is bent 90 degrees at a predetermined ratio at a position corresponding to the flange portion 11, and is led out of the ejector pin 300 from the groove 12 provided on the lower surface of the flange portion 11.
The optical fiber 5 is connected to a light receiving unit 21 that receives infrared rays. The light receiving unit 21 is connected to a display unit 25 of a laptop personal computer through variable resistors 23 and 24 as a preamplifier 22, a zero adjuster, and a gain adjuster. Is done.
Infrared light incident on the optical fiber 5 from the tip of the ejector pin 300 passes through the optical fiber 5 and is photoelectrically converted by the light receiving unit 21 and finally converted into a temperature signal and displayed on the display unit 25. Alternatively, the temperature signal is fed back to the control unit of the injection molding machine and used.

  In this embodiment, the optical fiber 5 has a diameter of 1 mm, and the tubular spacer 10 has an inner diameter of 1.1 mm, an outer diameter of 3 mm, and a length of 100 mm. The SUS tubular spacer was formed by pultrusion, and a tube having a small inner diameter could be obtained relatively easily. The hollow shaft portion 6 used had an inner diameter of 3.1 mm, an outer diameter of 5 mm, and a length of 200 mm. The flange 11 has a diameter of 9 mm and a thickness of 5 mm, and the lid member 13 has a diameter of 9 mm and a thickness of 3 mm.

  The ejector pin 300 according to the present embodiment has a length of 200 mm and an outer diameter of 5 mm, which is the same size as a standard ejector pin having no light guide. Therefore, the ejector pin 300 can be used in place of the ejector pin even in an existing mold for small precision parts.

  FIG. 2 is a cross-sectional view of a general mold. This mold is movable as a second mold plate provided with a fixed mold plate 32 provided with a cavity 31 and a fixed mold plate 32 provided with a core 33. They are opened and closed separately at the interface with the side mold plate 34. When the cavity is filled with resin, the ejector pin 300 functions as a light guide to measure the resin temperature, and functions as an ejector pin that protrudes from the core and protrudes out of the mold when the mold is opened. To do. In FIG. 2, the optical fiber 5, the light receiving unit 21, and the like are omitted.

The hollow shaft portion 6 has the same cross-sectional shape regardless of where it is cut as long as the tubular spacer 10 is fixed. Therefore, a semi-finished product having a long hollow shaft portion having the same dimensions is prepared in advance and ordered by the customer. The delivery of the pin with the length adjusted accordingly is made possible in a short period of time.
Further, since the gaps between the optical fiber 5 and the tubular spacer 10 and between the tubular spacer 10 and the enlarged diameter portion 2 are as narrow as 0.1 mm, the heat-resistant adhesive layer becomes thin and there is no fear that voids are generated inside. Further, the optical fiber 5 is not displaced from the center of the hollow shaft portion 6.

  The structure of the ejector pin 300 is verified from the viewpoint of the pressure resistance against the resin pressure during molding and the corrosion resistance against the gas volatilized from the resin. When the outer diameter of the hollow shaft portion 6 in the above embodiment is 5 mm, the outer diameter of the tubular spacer 10 is 3 mm, and the diameter of the optical fiber 5 is 1 mm, the hollow shaft portion 6 is 64% and the tubular spacer 10 is 32%. The optical fiber 5 is 4%, and the hollow shaft portion 6 and the tubular spacer 10 are mainly subjected to resin pressure during molding. In this embodiment, the tubular spacer 10 is supported by a step between the enlarged diameter portion 2 and the hollow portion 1 of the hollow shaft portion 6 and is bonded to the enlarged diameter portion 2 so that it does not shift and has a sufficient pressure resistance.

Next, since the tubular spacer 10 is made of SUS from the viewpoint of corrosion resistance, the corrosion resistance is not so inferior to that of SKD. The optical fiber 5 is also an oxide and has a relatively good corrosion resistance. A heat-resistant adhesive used as an adhesive is also mainly composed of an inorganic binder such as sodium silicate and potassium silicate and a filler such as alumina and zirconia, and has relatively good corrosion resistance. Therefore, the ejector pin 300 has no problem in terms of corrosion resistance.
As a material for the tubular spacer 10, aluminum or iron / copper whose surface is corrosion-resistant coated may be used in addition to SUS.

  Next, an outline of a method for manufacturing the ejector pin 300 will be described. First, a heat-resistant adhesive is applied to the outer surface of the tubular spacer 10 and inserted into the enlarged diameter portion 2 of the hollow shaft portion 6. The adhesive may be applied to the enlarged diameter portion 2. Next, the inner surface of the tubular spacer 10 is filled with a heat-resistant adhesive, and the optical fiber 5 bent in advance from the side of the flange 11 is inserted into the tubular spacer 10. The bending process of the optical fiber 5 can be performed by a known method such as thermoforming. After the optical fiber 5 is fitted into the groove 12 provided in the flange 11, the lid member 13 is fixed to the flange 11. And it heat-drys and is completed as a semi-finished product.

  The ejector pin 300 is cut within a range where the tubular spacer 10 is provided to adjust the length. Cutting is performed with a cutting grindstone while using a cutting fluid. Then, the tip is ground and flattened, and the surface of the optical fiber 5 is polished to complete.

  FIG. 3 shows an ejector pin 400 as another embodiment of the present invention. The configuration and main points in the figure are the same as those of the ejector pin 300 shown in FIG. The difference from the ejector pin 300 is that the enlarged diameter portion 2 is not provided in the hollow shaft portion 6.

In the ejector pin 300, in order to provide the enlarged diameter portion 2, it is necessary to perform drilling of the hollow portion 1 and drilling of the enlarged diameter portion 2, and finish processing such as reamer processing in order to adjust the shape of both steps. .
In the ejector pin 400, since the diameter-expanded portion 2 is eliminated, the above-described processing is only the drilling of the hollow portion 1, and the number of processing steps can be reduced.

In the ejector pin 400, the tubular spacer 10 cannot be supported by the step of the enlarged diameter portion 2, which is disadvantageous compared to the ejector pin 300 in terms of pressure resistance. As a countermeasure, a material having a larger thermal expansion coefficient than that of the hollow shaft portion 6 was used for the tubular spacer 10.
When resin injection pressure is applied to the ejector pin 400, the temperature of the mold including the ejector pin is close to 300 ° C. Since a highly rigid heat-resistant adhesive is filled between the hollow shaft portion 6 and the tubular spacer 10, a stress in the vertical direction is generated on the contact surface between the hollow shaft portion 6 and the tubular spacer 10 due to the difference in expansion coefficient. Thereby, the shift | offset | difference of both contact surface direction was able to be prevented.

In this embodiment, the thermal expansion coefficient of tool steel (SKD61) used as the material of the hollow shaft portion 6 is 125.4 × 10 ⁻⁷ , and the thermal expansion coefficient of SUS used as the tubular spacer 10 is 173 × 10 ^−7. It is. The strain due to the difference in expansion coefficient between the two at a molding temperature of 250 ° C. is assumed to be about 0.1%.

  As long as the thermal expansion coefficient of the tubular spacer 10 is larger than that of the hollow shaft portion 6 in the ejector pin 400, the material is not limited to the above example. For example, when tool steel (SKD61) used as the material of the hollow shaft portion 6 is used, aluminum or the like can be used as the tubular spacer 10.

It is a figure which shows the structure of the ejector pin with a light guide which concerns on one Embodiment of this invention. It is the figure which incorporated the ejector pin with a light guide which concerns on one Embodiment of this invention in the metal mold | die. It is a figure which shows the structure of the ejector pin with a light guide which concerns on one Embodiment of this invention. It is a figure which shows the structure of the conventional ejector pin with a light guide. It is a figure which shows the structure of the ejector pin with a light guide in the process leading to this invention. It is a figure which shows the structure of the ejector pin with a light guide in the process leading to this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hollow part 2 Expanded diameter part 3 Support sleeve 4 Sapphire cone 5 Optical fiber
6 hollow shaft portion 7 epoxy adhesive 8 void 10 tubular spacer 11 flange portion 12 groove 13 lid member 14 heat-resistant adhesive material 21 light receiving portion 22 preamplifier 23 zero adjuster 24 gain adjuster 25 display portion 31 cavity 32 fixed side template 33 Core 34 Movable side template

Claims (4)

A cylindrical hollow shaft,
A tubular spacer inscribed in the hollow shaft portion and fixed with a heat-resistant adhesive;
A cylindrical light guide that is inscribed in the tubular spacer and fixed with a heat-resistant adhesive,
The pin with a light guide, wherein the light guide, the tubular spacer, and the front end surface of the hollow shaft portion constitute substantially the same surface. 2. The pin with a light guide according to claim 1, wherein the light guide is an optical fiber having a core and a clad layer. The pin with a light guide according to claim 1, wherein a thermal expansion coefficient of the tubular spacer is larger than a thermal expansion coefficient of the hollow shaft. A first template having a cavity and a second template having a core and being movable relative to the first template are combined, and a resin is provided between the cavity and the core. In a mold for molding a molded product by filling
A cylindrical hollow shaft,
A tubular spacer inscribed in the hollow shaft portion and fixed with a heat-resistant adhesive;
A cylindrical light guide that is inscribed in the tubular spacer and fixed with a heat-resistant adhesive,
A molding die, comprising: the light guide, a pin with a light guide, the tubular spacer, and a tip end surface of the hollow shaft portion forming substantially the same surface.

Images