JPH0446207B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates generally to the manufacture of rubber products, and more particularly to molds for making annular articles of polymeric material.

The invention is most suitable for use in making toothed endless flat belts.

Other possible applications include making a series of circular articles from polymeric materials.

[Conventional technology]

Secondary forming surface (forming surface) for placing the molded product
a core with an annular insert together with a surface, two half-moulds, and a sealing element for pressure-sealing the forming interior or cavity of the molds; Molds for making tubular elastic shells are known. The sealing element is in the form of a groove in the plane where the mold halves are joined closely to the core, which extends along a generating line of the outer forming surface of the core. A similar type of seal is provided on the molding surface of the annular insert. The core is centered with respect to the mold half due to the tapered surface of the insert which is received by a corresponding groove in the mold half (1981
(See Bulletin No. 39, USSR Inventor Certificate No. 874386).

However, the complete pressure sealing of the molding interior space within this mold is such that while the mold halves are radially drawn together, the polymeric material fills the sealing groove and closes the mold halves. This is not possible as it will continue to escape through the gap between the joint surfaces. Therefore, sufficient pressure to produce a complexly shaped press-formed workpiece in the forming interior of the mold is not available by the time the joint of the mold halves closes, which means that the lining material ( This is especially true when using lining fabrics.

Molds for making hollow articles of polymeric material are also known, comprising two half molds and a composite core held in assembled position by a clamping device and a mandrel. The core has a shaped outer surface on which the molding is placed. The core is centered with respect to the halves when the halves are drawn together by means of a mandrel and a tapered insert on the distal face of the core and cooperating with a tapered hole in the halves. Aligned. The internal molding space is created at the joint between the mold halves by providing a recess in one mold half and a protrusion that enters the recess in the other mold half. pressure sealed along the sides. At the end, the molding interior space is sealed by a tapered insert of the core, which can be combined with the respective hole of the mold halves (Publication No. 6 of 1982, USSR Inventor's Certificate, etc.)
(See No. 905111).

One of the disadvantages of the above-mentioned molds is that the polymeric substances tend to flow outward through the gaps between the faces of the mold halves and the inserts, especially at the beginning of the press-forming process. At the time of
The problem is that the pressure sealing of the internal molding space of the mold is insufficient. By the time a complete pressure seal is obtained, the press forming procedure is finished and therefore the pressure developed in the forming interior space is not sufficient to accurately replicate the shape of the article.

[Problem that the invention seeks to solve]

The present invention provides a means for pressure sealing the molding interior space or cavity of the mold to ensure reliable pressure sealing of the molding interior space throughout the entire process of press forming the article, thereby improving the quality of the final product. It is an object of the present invention to provide a mold for making a circular article of polymeric material, which is configured to produce a circular article of polymeric material.

It is therefore an object of the present invention to provide a mold for making annular articles of polymeric material that allows for the production of articles of higher quality.

[Means for solving problems]

This object of the invention is to provide a core with a shaped outer surface for placing the molded article, holes for draining excess polymeric material, and a two mold halves surrounding a surface and partially surrounding an end face of said core, and means for pressure sealing a cavity of the mold to prevent molding material from escaping the cavity. According to the present invention, in a mold for making an annular product of a polymeric substance, when the half-split molds are joined to each other while surrounding the outer molding surface of the core, the core of these half-split molds is The length of the portion facing the outer molding surface of the core is equal to the length of the generatrix of the molding outer surface of the core,
On the other hand, the means for pressure sealing the cavity includes two members fixedly attached to one of the mold halves on opposite sides thereof, and the mold halves are connected to each other. This is achieved by having a U-shaped shape that surrounds these half molds in the area to be joined, and also during the press molding process, a part of the end faces of these half molds and the core are connected to the core of the member. This is achieved by enclosing the parts corresponding to the opposing upper and lower sides of the character.

Preferably, holes for draining excess polymeric material are provided on the end sides of each mold half in the area where the mold halves form the article. Each hole for discharging excess polymeric material is preferably closed by a spring-loaded plunger, the spring-loaded plunger having an opening for discharging excess polymeric material in the open position of the plunger. There is a relief hole leading to the hole.

[Effect]

Providing a plunger in the hole for expelling excess polymeric material controls the compression pressure of the molding interior space of the mold, thus providing optimal conditions for obtaining high quality polymeric material articles. make it possible.

The mold for making the circular article of polymer material embodying the present invention is structurally simple, but
Ensures complete pressure sealing of the cavity while making articles of polymeric material, resulting in a higher quality final product.

〔Example〕

The mold for making a toothed belt from a polymeric material consists of two half-split molds 1 and 2 (Fig. 1), and
It comprises a core 3 having an outer surface shaped with a toothed surface on which a molding 4 is arranged, the molding comprising:
It comprises a lining, a carrying cord, and a polymeric material (the materials making up the molding are not shown in the drawings).

The core 3 is of two types extending in the axial direction, mounted on the central shaft 7 and held in its mounted state by cover plates 8, 9 (FIG. 2) drawn together by a nut 10. including sectors 5 and 6.

The mold halves 1, 2 (FIG. 1) have cylindrical inner surfaces, so that the mold halves surround the shaped surface of the core 3, and the shell 12 (FIG. 3) has a cylindrical inner surface. Adjacent to the end surface of the core 3, the tapered end surface 13 is correspondingly adjacent to the tapered side surface of the cover plates 8, 9. Tapered surface 13 of shelf 12 of half-split molds 1 and 2
The engagement of the core 3 with the tapered side surfaces of the cover plates 8, 9 ensures alignment of the core 3 with respect to the cylindrical shaped surface 11 of the mold halves 1, 2.

The mold halves 1, 2 are used to mold the core in order to pressure seal the molding internal space or cavity defined by the space between the shaped surface of the core 3 and the cylindrical mold surface 11 of the mold halves 1, 2. The length H (Fig. 2) of the portion of these half molds facing the outer molding surface of the core when the outer molding surface is surrounded and joined to each other is the length H of the outer molding surface of the core 3. Equal to the length of the generatrix. What is used as a sealing means is fixedly attached to the half-split mold 2 on its opposite side with a bolt 15, and the half-split mold 1, 2
(FIG. 1) are two members 14 extending along the sides and overlapping the joint. Each member 14 is
As best seen in Figure 2, it is shaped like a U-shape, and the inside of the U-shape faces the half molds 1 and 2. Since the length of the inner surface of the member 14 corresponding to the vertical line of the U-shape is equal to the length H (FIG. 2) of the half-split molds 1 and 2 (FIG. 1),
The member 14 surrounds the mold halves 1, 2 in the area where the mold halves 1, 2 join together. In addition, a portion 1 corresponding to the opposing upper and lower sides of the U-shape of the member 14
6, the member 14 surrounds a portion of each end face of the mold halves 1, 2 as well as the core 3 during the press molding process. The height h (Fig. 1) of the member 14 is
It must be sufficient to overlap the joint between mold halves 1 and 2.

Excess polymeric material is transferred from this inner space to the shell 12 of the half molds 1 and 2 (Fig. 3) at the inner space for press molding at the farthest position from the joint between the half molds 1 and 2. A hole 17 (FIG. 4) is provided which serves to drain the water. The locations of these holes 17 are indicated by circles A in FIG.

In the embodiment described herein, two closely spaced holes 17 (FIG. 4) are provided in each mold half 1,2. The bore 17 is closed by a plunger 19 which is biased by a spring 18. Plunger 19 (FIGS. 4 and 5) has a central relief hole 20 that can communicate with bore 17 (FIG. 4) when plunger 19 is open.

The force of the spring 18 is adjusted with a screw plug 21.

The mold according to the invention is operated in the following manner.

A lining is placed on the installed core 3, after which the carrying cord is wrapped and a layer of polymeric material is applied thereto. Then, the core 3 together with the molded product 4 is placed in the lower half mold 2 such that its end face is placed in the space defined by the inner surface of the shelf 12 of the half mold 2. The weight of the core 3 together with the molding 4 causes it to partially lower into this space and align coaxially with the cylindrical-forming surface 11 of the lower mold half 2. Thereafter, the lower half mold 2 is molded so that the side surface of the upper half mold 1 is placed inside the U-shaped part of the member 14 fixedly attached to the lower half mold 2 on its two opposing sides. Place the upper half mold 1 on top of the core 3 together with the object 4. The upper half mold 1 partially surrounds the end surface of the core 3 on the inner surface of the shelf 12. The member 14 overlaps the joint between the mold halves 1 and 2 and partially overlaps the core 3. In this method, the core 3 together with the molding 4 occupies the internal molding space. The hole 17 for draining excess polymeric material is closed by a plunger 18. In this state, the mold is adjusted between the plates of the vulcanization press to draw the upper and lower mold halves together, thereby moving them radially. As the halves are drawn together more tightly, the core 3 is moved into its cylindrical shape by the cooperation of the tapered surfaces of the cover plates 8, 9 and the tapered surface 13 of the shield 12. Center and align with respect to the formed surface. The pressure of the polymeric material in the molding internal space without pressure leakage increases to its optimum value, thereby causing the polymeric material to have the property of following the shape of the core 3 as it occupies the shape of the molding. Ensures that the lining stretches evenly. The spring-loaded plunger 19 is adjusted to the optimum pressure, and when this pressure is reached, the mixture of polymeric and gaseous substances flows out through the hole 17 for draining the excess polymeric material and the plunger 19 It moves and leaks out as waste through the escape hole 20 to the outside. As a result of discharging the excess polymeric substance and gaseous substance, the pressure in the molding internal space without pressure leakage is reduced to the optimum pressure again due to the plunger 19, and a hole is opened for discharging the excess polymeric substance. 17, thus maintaining the pressure of the polymeric material therein, which ensures a relatively high quality pressing. After the upper and lower half molds 1 and 2 are joined, the volume of the internal space for molding becomes stable and leakage of excess polymeric material is stopped, but a plunger with closed hole 17 for discharging excess polymeric material is used. 19 maintains the pressure of the polymeric material in the molding internal space without pressure leakage until the vulcanization process is completed.

After vulcanizing the molded product, the press plate is separated, then the half mold 1 is removed, and the core 3 is taken out together with the final product. After removing the core 3, the product is removed from it and later cut into products of the required width.

Before the next press forming operation, the holes 17 for draining excess polymeric material and the central hole 20 are cleaned of residual polymeric material. When the composition of the polymeric material, which is a parameter of pressure forming and vulcanization, is changed, products of even higher quality can be obtained by supplying the optimum pressure of the polymeric material suitable for the new processing conditions to the molding internal space of the mold. The force required to open plunger 19 with the purpose of obtaining
Adjustment is made by rotating the screw plug 21 acting at 8.

〔Effect of the invention〕

having means for pressure sealing the molding interior space or mold cavity and comprising means for regulating the pressure in the molding interior space, which is particularly adapted for operation with viscous polymeric materials; In addition, the relatively simple structure of the mold proposed here for making circular articles of polymeric materials makes it possible to control the molding process and obtain high-quality articles of polymeric materials. Become.

Pilot models of the proposed mold
has been tested. 1.5, 2, and 3 mm modulus toothed belts with wear-resistant linings on the teeth were fabricated. When tested on textile machines and stitchers, such belts have a 4 to
It could be used for 6 times longer.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of one half of a mold for making an annular article of polymeric material. Figure 2 shows the first
It is a sectional view taken along the line - in the figure. FIG. 3 is a sectional view taken along the line -- in FIG. 1. FIG. 4 is a longitudinal cross-sectional view showing a hole and a plunger for discharging excess polymeric material. FIG. 5 is a sectional view taken along the - line in FIG. 4. In the figure, 1 is the upper half type, 2 is the lower half type, 3
is a core, 4 is a molded product, 5 and 6 are sectors, 7 is a center shaft, 8 and 9 are cover plates, 10 is a nut, 11 is a half-split cylindrical inner surface, 12 is a shelf, 13 is a tapered surface, 14 15 is a bolt, 16 is a portion corresponding to the opposing upper and lower sides of the U-shape of member 14, 17 is a hole for discharging excess polymeric material, 18 is a spring, 19 is a plunger, and 20 is a center An escape hole, 21 is a screw plug, H is the length of the portion of the core 3 facing the outer molding surface where the half molds are joined, and h is the height of the member.

Claims (1)

[Claims] 1. A core 3 having a shaped outer surface for disposing a molded product 4, a hole 17 for discharging excess polymeric material, and during press molding,
Two mold halves 1, 2 surrounding the outer surface and partially surrounding the end face of the core 3, and the cavity of the mold are pressure-sealed to prevent molding material from escaping the cavity. A mold for making an annular article of a polymeric substance, the mold comprising a means for making a circular article of a polymeric material, wherein the half molds 1 and 2 are joined together surrounding the outer molding surface of the core. The length H of the portion of the half mold facing the outer molding surface of the core is equal to the length of the generatrix of the outer molding surface of the core 3, and the means for pressure sealing the cavity is formed of two 14, which are fixedly attached to one of the mold halves 2 on opposite sides thereof, and which are attached to one of the mold halves 1, 2 in the area where the mold halves 1, 2 join together. 2, and during press molding, the half molds 1, 2 and the A mold characterized by surrounding a part of the end face of the core 3. 2. A hole 17 is provided in each of the half molds 1 and 2 for discharging excess polymeric material on the end side surface of the half mold in the area where the article is to be molded, and a hole 17 is provided for discharging excess polymeric material. Each of said holes 17 for the purpose of the invention is closed by a spring-loaded plunger, characterized in that said plunger has, in the open position of said plunger, a relief hole 20 communicating with the hole 17 for draining the excess polymeric material; A mold according to claim 1.