RU2457942C1 - Method of preparing moulds for production of reinforced rubber articles - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of rubber articles by curing on mould and may be used for making reinforced shock-absorbers and elastic thrust hinges. Proposed method comprises mounting mould on press bottom plate, attaching male die to press top plate, placing elastomer in mould loading chamber and lowering male die therein. Note here that expanding ring is made with outer diameter fitting with loading chamber inner diameter. Then, expanding ring is arranged on loading chamber bottom to lower male die into the latter to contact with expanding ring. Male die is centered relative to loading chamber and attached to press top plate. Then, male die is lifted to remove expanding ring elastomer is placed into loading chamber to down male die and level elastomer surface. Thereafter, male die is lifted to place expanding ring on leveled surface, and lowered again.

EFFECT: higher reliability.

3 dwg

Description

The invention relates to the field of engineering, in particular to the technology of manufacturing rubber products by vulcanization in the mold, and can be used in the manufacture of reinforced shock absorbers and elastic supporting joints (EOS).

Known molds for the manufacture of reinforced rubber products (see, for example, patents of the Russian Federation No. 2131998 and 2302944).

These molds contain a cylindrical loading chamber filled with an elastomer with a punch moving in it, a forming block and a gating system.

Hydraulic presses are used for pressing, providing constant pressure on the pressed part during the whole pressing time, while the upper movable plate is pressed against the press mounted on the lower fixed plate and the mold fixed on it with the elastomer loaded into it when moving the press plunger it with a mold punch, and the elastomer is extruded from the loading chamber through the gating system into the forming block, where the elastomer is pressed.

There is a method of preparing a mold for manufacturing reinforced rubber products, including installing a mold on the lower press plate, fastening the mold punch with the upper press plate, placing the elastomer in the mold loading chamber and lowering the punch into it (see IM Bulanov, VV Vorobei. Technology of rocket and aerospace structures from composite materials. - M.: Publishing House of MSTU named after NE Bauman, 1998 - pp. 165-168) - the closest analogue.

The application of the known method in the manufacture of an EOS of a large-sized nozzle block of a solid propellant rocket engine (RDTT) has shown that in a mold prepared for operation with a cylindrical loading chamber of significant size when the punch moves under the pressure of the press, elastomer can exit out of the loading chamber outward, by a gap between the punch and the inner wall of the loading chamber.

This leads to the need for secondary loading of the mold chamber with an elastomer to provide the amount required for molding the product, which leads to an increase in the cost and complexity of the method.

Additional centering of the punch relative to the loading chamber before fastening it to the upper press plate, which can be done in preparation for the mold to work in a known manner to ensure a uniform perimeter gap between the punch and the inner surface of the loading chamber, does not completely exclude the possibility of the elastomer leaving the loading chamber chambers outward in the gap between the punch and the inner wall of the loading chamber, since with large dimensions of the loading chamber and, accordingly, of the punch, the amount of guaranteed uniform clearance can be significant.

Thus, the preparation for the operation of the mold in a known manner does not exclude the possibility of the elastomer leaving the pressing chamber from the loading chamber to the outside through the gap between the punch and the inner wall of the loading chamber, which reduces the reliability of the mold.

The technical task of this invention is the development of a process for preparing for the operation of the mold, which increases the reliability of the mold by eliminating the possibility of elastomer exit during pressing from the loading chamber to the outside by the gap between the punch and the inner wall of the loading chamber.

The technical result is achieved by the fact that in the method of preparing the mold for manufacturing reinforced rubber products, including installing the mold on the bottom plate of the press, fastening the punch of the mold with the top plate of the press, placing the elastomer in the loading chamber of the mold and lowering into it a punch, an expanding ring is made, the outer diameter of which corresponds to the inner diameter of the loading chamber, a expanding ring is installed on the bottom of the loading chamber, and lowered into the loading chamber at the punch, before contact with the expanding ring, center the punch relative to the loading chamber and fasten it to the upper press plate, then lift the punch and extract the expanding ring, place the elastomer in the loading chamber, lower the punch and align the surface of the elastomer, then lift the punch, install the expandable ring on the aligned surface of the elastomer and again lower the punch into the loading chamber.

Carrying out the centering of the punch relative to the loading chamber at the beginning of the preparation process for the operation of the mold, before loading the elastomer and when the expanding ring is installed on the bottom of the loading chamber, makes it possible to most easily center with the most accurate simulation of the working conditions of the mold and carry out further operations on preparation with a centered punch bonded to the upper press plate.

The centering of the punch relative to the cylindrical loading chamber of the mold, which can be carried out, for example, using a specially designed detachable centering ring, allows for an even gap between the punch and the inner surface of the loading chamber, which is important for reliable operation of the mold.

Aligning the surface of the elastomer in the loading chamber before installing the expansion ring allows you to most easily and without tilt to install the expansion ring on the aligned surface of the elastomer, which is required for reliable operation of the mold.

Installing the expanding ring on the aligned surface of the elastomer without skew eliminates the possibility of jamming of the expanding ring in the loading chamber when it moves together with the punch and completely eliminates the possibility of extruding the elastomer during mold operation into the guaranteed gap between the punch and the loading chamber.

The developed set of technological operations carried out in a strictly defined sequence allows you to best prepare the mold for work while ensuring the required manufacturability.

The essence of the method is illustrated by drawings.

Figure 1 shows a diagram of a mold with an expandable ring mounted on the bottom of the loading chamber.

Figure 2 shows a diagram of a mold with an elastomer in the loading chamber and a punch installed to level the surface of the elastomer.

Figure 3 shows a diagram of the mold with an expandable ring mounted on the aligned surface of the elastomer.

Preparation of the mold for work by the proposed method is carried out in three stages as follows.

An expansion ring is made whose outer diameter corresponds to the inner diameter of the mold loading chamber.

The expanding ring is made in the form of a spring ring with a through cut in one of the cross sections.

Install the pre-assembled mold on the lower fixed plate of the press and fix it (not shown in the figures).

In the process of preparing the mold for operation, first, an expansion ring 2 is installed on the bottom of the loading chamber 1.

Lower the punch 3 into the loading chamber 1 until it contacts the expanding ring 2, center the punch 3 relative to the loading chamber 1 and fasten the punch 3 with the upper press plate (not shown in the figures).

Then the punch 3 is lifted and the expanding ring 2 is removed, the elastomer 4 is placed in the loading chamber 1, the punch 3 is lowered and the surface of the elastomer 4 is aligned with it.

Then raise the punch 3, install the expanding ring 2 on the aligned surface of the elastomer 4 and again lower the punch 3 into the loading chamber 1.

During the pressing process, when moving the plunger of the press, its upper movable plate with the punch 3 moves to the mold, as a result of which the punch 3 together with the expanding ring 2 moves along the walls of the loading chamber 1 and the elastomer 4 is pressed into the product.

Using the proposed method, which increases the reliability of the mold, a number of high-quality EOSHs of large-sized RDTT nozzle blocks were manufactured while ensuring the required manufacturability.

Claims (1)

A method of preparing a mold for manufacturing reinforced rubber products, comprising installing a mold on a lower press plate, fastening a mold punch to an upper press plate, placing an elastomer in a mold loading chamber and lowering a punch into it, characterized in that an expansion ring is made, the outer diameter of which corresponds to the inner diameter of the loading chamber, the expansion ring is installed on the bottom of the loading chamber, the punch is lowered into the loading chamber until it contacts p with a clamping ring, center the punch relative to the loading chamber and fasten it to the upper press plate, then lift the punch and take out the expanding ring, place the elastomer in the loading chamber, lower the punch and align the surface of the elastomer, then lift the punch, install the expandable ring on the leveled surface of the elastomer and again lower the punch into the loading chamber.

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