JPH036411Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a plunger used in a mold for resin molding.

[Conventional technology]

Plungers that have been used for resin molding molds so far have been made of steel and have a one-piece shape, or the head 1 is made of cemented carbide as shown in Figure 6, and the steel holder 3 has a flat surface. Brazed types are known. This head uses cemented carbide,
The carbide head has greater wear resistance compared to the head wear of steel plungers, resulting in a longer service life.

[Problem that the invention attempts to solve]

However, when a carbide head is brazed to a steel holder in one plane, distortion occurs in the brazing surface due to the difference in thermal expansion coefficient between carbide and steel, and brazing stress occurs. This brazing stress often caused problems such as breakage at the brazed portion during the manufacturing process and during use. If the carbide head is damaged, the entire plunger is usually discarded. In some cases, it is possible to reuse the holder, but since the brazing temperature is 700 to 800°C, the accuracy of the holder is likely to be lost, and the brazed head must be ground to ensure accuracy. This process is necessary, and the cemented carbide itself is expensive.
In either case, the cost burden is large.

The object of the present invention is to solve the above-mentioned problems and provide an economical and high-performance plunger for resin molding that is inexpensive and free from head damage due to brazing stress.

[Means for solving problems]

In order to achieve the above object, the present invention has the following structural requirements. That is, it is a plunger for resin molding that is composed of a head, a joining member, a holder part, and a bolt, and one end of the joining member is fitted into a recess on the back side of the head made of cemented carbide or ceramic. , the other end of the joining member is removably attached to the holder part with a bolt from the rear of the holder part, and the other end of the joining member is attached to the head part so as to be fitted and adhered to the head part. 1. A plunger for resin molding, characterized in that a plurality of grooves are formed in the longitudinal direction of the outer peripheral surface at one end, that is, the joint part, to relieve stress generated by brazing the head.

[Effect]

Due to the difference in thermal expansion coefficient between the cemented carbide or ceramic head and the steel joint member, the stress generated by brazing is dispersed and absorbed by the multiple unbrazed grooves in the joint of the joint member, and the stress is significantly reduced. This reduces head damage and prevents damage to the head. The effect of reducing this brazing stress is that the cross-sectional shape of the joint is solid with grooves, hollow with grooves, and hollow with split shapes, in that order.
Moreover, the greater the number of grooves and the greater the groove depth, the greater the effect. However, making it hollow, increasing the number of grooves, or increasing the depth of the grooves will reduce the strength of the joint, so the outer diameter of the plunger,
It is necessary to select it appropriately within a range that maintains the required strength depending on the conditions of use.

Furthermore, since the bolt 4 has a long shaft, it is difficult for the joint member to loosen due to its tension, and the joint member having a head can be securely screwed into the holder part by screwing the joint member with a bolt from the rear of the holder part. be able to.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of the plunger, and FIG. 2 is an exploded view of the plunger, with a portion of FIG. 1 cut away. 1st
2, the plunger of the present invention consists of a head 1 made of cemented carbide (equivalent to JIS K40), a joining member 2 and a holder part 3 made of steel, and a hexagon socket head bolt 4.

The head 1 has a cylindrical recess 11 . The joining member 2 includes a fitting portion 23 and a plurality of longitudinal grooves 2.
2, and an inner diameter threaded portion 24 on the opposite side of the joint portion 21. The holder part 3 has an inner diameter fitting part 31 at one end and a hexagon socket head bolt 4 inside.
It has a bolt hole 32 and a counterbore portion 33 for accommodating it, and is screwed onto a ram (not shown) of a press machine by a threaded portion 34 at the other end opposite to the inner diameter fitting portion 31.

After the head recess 11 is fitted into the joint part 21 of the joint member 2 and fixed by brazing, the head outer diameter part 12 and the fitting part 23 of the joint member are arranged so that they have approximately the same center line as the inner diameter threaded part 24. The outer periphery is polished to the desired dimensions.

The joining member 2 is attached to the holder by fitting the fitting part 23 into the inner diameter fitting part 31 of the holder part 3 and screwing the hexagon socket head bolt 4 inserted from the rear of the holder part 3 into the inner diameter threaded part 24. 3
can be attached to. In addition, the positioning in the longitudinal direction is
This is done by abutting the end surface 13 of the head 1 brazed to the joining member 2 with one end 35 of the holder part.

Next, FIG. 3 is a cross-sectional view taken along arrow XX in FIG. 2, showing the cross-sectional shape of the joint 21 in the joint member 2. The stress generated by brazing is absorbed by the groove 22 that is not brazed. Although a slight change occurs in the groove width, the stress is dispersed and removed, and damage to the head due to brazing stress can be prevented.

FIG. 4 shows another example of the cross section of the joint shown in FIG.
In FIG. 4a, the joining part 21 is hollow and has a groove, and the hollow shape can be easily manufactured by passing a drill having the same diameter as the prepared hole when processing the threaded part 24. FIG. 4b shows a case where the groove 22 is hollow and the depth is equal to the thickness of the joint 21, that is, the cylindrical joint 21 is divided. Note that the shape of the head recess 11 and the joint portion 21 of the joint member 2 is the same as that of the fifth
It may also be conical as shown in the figure, which is better for the head 1.
Since concentricity can be achieved between the joint member 2 and the joint member 2, there is no fear of misalignment due to brazing, and the amount of polishing of the outer diameter portion 12 of the head after brazing can be set to be smaller.

Further, the cylindrical fitting portion between the joining member 2 and the holder portion 3 may also be formed into a conical shape (not shown), which maintains concentricity.

[Effect of idea]

The present invention allows the work to be carried out by simply replacing the joining member having a head, and by using a bolt with a long shaft, the joining member is tightly packed in the holder and securely fixed. In addition, by devising the shape of the brazed joint, we were able to significantly reduce the brazing stress, which was a major cause of failure in conventional carbide heads, resulting in longer life and an economical and A high-performance plunger for resin molding can be provided.

Furthermore, by providing a concave portion on the back of the head, it is possible to reduce the weight of cemented carbide or ceramic, which has a high unit price per gram, so that it can be manufactured at a lower cost than before.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a plunger for resin molding according to the present invention, Fig. 2 is a partially sectional exploded view of the plunger of Fig. 1, Fig. 3 is a sectional view taken along the XX arrow in Fig. 2, and Fig. 4a, b. The drawings are a cross-sectional view showing another embodiment of the plunger shown in FIG. 3, FIG. 5 is a cross-sectional view showing another combination of the head and the connecting member, and FIG. 6 is a partial cross-sectional view of a conventional plunger. DESCRIPTION OF SYMBOLS 1... Head, 2... Joining member, 3... Holder part, 4... Bolt, 11... Recessed part, 21... Joining part, 22... Groove.

Claims (1)

[Claims for Utility Model Registration] (1) A plunger for resin molding consisting of a head, a connecting member, a holder, and a bolt, wherein one end of the connecting member is made of cemented carbide or ceramic. The other end of the joining member is inserted into a recess on the back of the holder and fixed by brazing, and the other end of the joining member is bolted from the rear of the holder so that it is approximately concentric with the center line in the longitudinal direction of the holder. A plurality of grooves are formed in the longitudinal direction of the outer circumferential surface at one end of the joining member, that is, at the joining portion, which is removably attached to the holder part by a screw and is to be brazed and bonded to the head, A plunger for resin molding, characterized in that stress generated by brazing the head part is alleviated. (2) Utility Model Registration Claim 1: The plunger for resin molding, characterized in that the shape of the joint portion of the joint member is cylindrical or conical. (3) Utility Model Registration The plunger for resin molding according to claim 1, characterized in that the shape of the joint portion of the joint member is cylindrical or conical with a longitudinal hollow portion in the center. (4) The resin according to claim 3 of the utility model registration, characterized in that the depth of the groove is equal to the wall thickness of the joint part and the joint part is divided in the circumferential direction. Plunger for molding.