RU2131807C1 - Casting mold - Google Patents

Abstract

FIELD: production of electrically isolating parts from ceramics. SUBSTANCE: casting mold for manufacture of billets by hot slip pressure die casting method has plate covering signs, columns, sign holder, column signs, removable plate, die, main runner plate and auxiliary runner plate positioned between main runner plate and die. EFFECT: simplified construction and increased casting yield. 5 dwg

Description

 The invention relates to the production of ceramic parts mainly for electrical purposes and can be used in the ceramic industry.

The hot slip casting process consists of the following methods [1,2]: installation of the assembled injection mold with a sprue hole in the sprue plate on the sprue hole of the casting machine, then, after pressing the mold to the sprue hole of the casting machine and applying pressure, the hot slip is fed into the workspace injection mold. Typically, the temperature of the slip is selected 50-70 ^o C, pressure: 2.0 - 6 atm. After filling the working space of the injection mold, the supply of the slip stops and the process of solidification of the workpiece begins, as a result of which the workpiece acquires the necessary strength, then, after releasing the pressure of the clamp, the gate is cut and the mold is disassembled to remove the workpiece. The diameter of the sprue plate opening through which the hot slurry under pressure enters the working space of the injection mold, and its configuration along the height of the sprue plate are selected from the conditions for ensuring the quality of casting and the convenience of cutting the gate with minimal damage to the workpiece surface. In the case of a symmetrical workpiece, the sprue hole is usually positioned along the axis of the workpiece, usually in a single injection mold. The sprue hole can also be located along the axis of the sprue plate when developing a multi-place injection mold with relatively small diameters of the workpieces, which are arranged uniformly around the circumference in the matrix and symmetrically with respect to the sprue hole. The sprue hole, in this case, is selected according to the configuration as for a single injection mold and an additional sprue is made, which forms a special cavity in the sprue plate. Such an additional gate covers all working spaces and has a sufficient cross-section for supplying the required amount of slip in each working space when casting, including taking into account shrinkage phenomena. A massive sprue is formed, the cutting of which is very problematic, since the slip acquires sufficient strength during cooling. In FIG. 1 shows a casting consisting of ten blanks of electrical insulating bushings located on a gate. When breaking the workpieces from the gate (Fig. 2), the marriage is 100%, since the place and quality of the surface along the line of breaking is unpredictable. For contrast, the quality of the break line is unpredictable. To contrast the image of the configurations of fracture forms on the gate, they are tinted. In the workpiece from the end, the breaking shape is arbitrary. Other methods of separating blanks from the gate are extremely time-consuming.

 The aim of the invention is to increase the yield of workpieces after casting and, in particular, after cutting the gate to 100%. This goal is achieved by the fact that an additional sprue plate 2 - 3 mm thick, which is located between the main sprue plate and the die, is introduced into the known mold design.

 The essence of the invention lies in the fact that the cutting of each sprue of the billet blank is performed in the same modes and with the same tool as the main sprue, i.e. ensuring the quality of the end surface of each workpiece, which ensures 100% yield after casting. In FIG. Figure 3 shows the blanks of bushings with sprues, formed in the holes of an additional gate plate, which are cut after removing the additional gate plate at a time when the blanks of the bushings are still in the matrix (i.e., as provided for in the designs of known injection molds). The break points are tinted. In the workpiece from the end, the shape of the break-off is a regular circle. In FIG. 4 shows the construction of the mold in working position on the table of the casting machine, pressed against the gate hole.

 The mold consists of a plate 1, covering the signs 2, column 3, sign holder 4, removal plate 5, matrix 6, an additional sprue plate 7 with sprue holes 8, the main plate 9 with a sprue hole 10. After arranging the sprue hole 10 of the sprue plate 9 above the injection hole of the slip of the injection molding machine and the pressure of the injection mold presses P to the slip in the working spaces of the injection mold. The slurry is supplied under pressure Рш through the cavity 11 in the main runner plate 9 and the runner holes 8 in the additional runner plate 7. At the end of the filling cycle, a short time is automatically taken to start the workpiece. The pressure release Рш occurs simultaneously with the release of force P, after which the injection mold is removed from the table of the injection machine. Next, the sprue is cut in the sprue hole 10 of the main sprue plate 9 and this plate is removed from the casting columns 3. After that, the injection mold is installed on the supports 12 (Fig. 5) and the applied force Rl through the hole 13 separates the blanks of the bushings located in the matrix 6 from the gate, decorated in the cavity 11. The gate openings 8 in the additional gate plate are made on a cone, so that the workpieces of the products do not come out of the matrix 6 when removing the additional gate plate 7. Then, the gate is cut in each workpiece, followed by the removal of the workpieces from signs 2 and pushing them out of the matrix 6.

 The manufactured batch of ceramic electrical insulating two-channel bushings had higher electrical insulating characteristics compared to the broaching method, although this method is less time-consuming compared to hot slip casting. The drawback of the broaching method is the lack of uniformity in the structure of the workpiece and the need to observe the exact temperature regime of heating (with decreasing temperature of the slip, the pulling force increases sharply, with increasing - the slip melts) [1,2].

In the manufacture of a batch of such ceramic bushings in the amount of 50,000 pcs. from vacuum-tight corundum ceramics of the VU 100 - 1.2 grade (polycor), the yield after casting was 100%. Such products are used in the manufacture of twenty-five meter thermocouples to control the temperature of CHP boilers. There were no operating notes at temperatures of 1000 ^o C. Moreover, due to the higher quality of the ceramic structure of electrical insulating sleeves made by hot slip casting, compared to broaching, there was the exception of shunting e. d.s thermocouples with increasing operating temperatures. This increased the accuracy of temperature control, which improves fuel economy. Similar results were obtained at KAMAZ JSC in Naberezhnye Chelny and at the Almetyevsk submersible pump plant (Tatarstan) when casting silicon carbide o-ring blanks for submersible oil pumps and for the water pump of the KAMAZ-740 diesel engine. In the first case, the use of such o-rings made it possible to increase the operating time of the unit from 15,000 hours to 20,000 hours, in the second case, the warranty service life of the engine's sealing unit for the entire life of the engine of the Kamaz automobile was increased.

Bibliographic data
1. Gribovsky P.O. Hot slip casting of ceramic products. - M.: Gosenergoizdat, 1961, p. 250
2. Gribovsky P. O. Ceramic solid circuits - M .: Energy, 1971, p. 498x

Claims (1)

 Injection mold for the manufacture of billets by hot slip casting, consisting of a plate covering signs, columns, a sign holder, signs of columns, a removal plate, a matrix, a connector and a runner, characterized in that a second runner is introduced into the mold design between the main runner plate and the die.

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