RU2455101C1 - Heat-insulation pads for dies - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to metal forming, particularly, to isothermal moulding of magnesium and aluminium alloys. Heat-insulation pad arranged under die and die plate comprises metal sheets. Flexible interlayers are arranged between said sheets. Said sheets are made from metal with heat conductivity lower than 30 W/m·degree while interlayers feature heat conductivity lower than 1 W/m·degree. Pad base and top sheet feature thickness exceeding that of interlayers. Pad base and top sheet have grooves to receive thread bush and flanges aligned therewith. Top sheet is secured to base by said thread bushes and flanges that may displace axially.

EFFECT: decreased heat transfer from hot die to press components, hence, slower die cooling.

2 cl, 1 dwg

Description

The invention relates to equipment for metal forming and can most effectively be used for isothermal stamping of parts from aluminum and magnesium alloys.

An analogue of the claimed technical solution is the “Stamp for hot deformation”, copyright certificate of Y.M. Okhrimenko et al. No. 462647, announced on March 12, 1973, in which the stamp is equipped with a heat-insulating casing to reduce heat loss. The disadvantage of the analogue is low heating efficiency and increased heat loss through the supporting surfaces of the stamp, because tool blocks (stamp) with a punch and die fixed on them are supported by monolithic gaskets that do not provide sufficient thermal insulation of the stamp from the press in which it is installed.

The prototype of the claimed technical solution is a heat-insulating device, described in the book "New in the creation and research of forging machines", Moscow 1983 (Sat. Scientific works of VNIIMETMASH), in the article by V.P. Linz and E. B. Shaykevich " Thermal insulation device for a powerful hydraulic press die ”, p. 34 ... 37.

According to the prototype, as a heat-insulating device, you can use a set of several thin steel plates or sheets - a multilayer gasket in which the very border between the sheets (microroughness) prevents the transfer of heat from the heated stamp to the press parts.

The disadvantage of the prototype is the high heat loss through a set of steel sheets to the parts of the press due to the high thermal conductivity of the sheets.

The technical result of the invention is to reduce heat dissipation from the heated stamp to the parts of the press and, therefore, reduce its cooling rate.

The technical result is achieved by replacing steel sheets with high thermal conductivity with sheets with a thermal conductivity of less than 30 W / m · deg, between which flexible gaskets are installed with a thermal conductivity of less than 1 W / m · deg; the top sheet is bolted to the base with threaded sleeves and flanges, while the base of the pillow and the top sheet have a thickness exceeding the thickness of the intermediate sheets and are made with grooves for mounting the threaded sleeves and flanges aligned with them, with the possibility of their axial movement.

The proposed thermal insulation pillow is depicted in figure 1.

The pillow consists of alternating sheets of metal 1 with low thermal conductivity and flexible gaskets 2 in the form of sheets or fabric mainly based on oxide ceramics. Grooves are made in the base of the pillow 3, into which the flanges 4 are inserted, coaxially with which the threaded sleeves 5 are located, fastened with pins in the top sheet 6. The base of the pillow 3 and the top sheet 6 are pulled together by bolts 7. In sheets 1 and gaskets 2 in the attachment points grooves are made with a diameter not less than the diameter of the protruding part of the threaded bushings 5. Parts 3, 6 and 7 can be made of a material with low thermal conductivity, or of die steel. The pillow is centered on a sub-die plate 8 with a sleeve 9 and, if necessary, a hole is made in it for the ejector of the press. Stamp 10 is placed on the pillow. The upper pillow, unlike the lower one, is additionally equipped with flanges 4 for attaching the pillow directly to the upper sub-stamp plate 11 with bolts 12.

Before work, screw bolts are screwed into the holes of the threaded sleeves 5 and the pillow is mounted on a sub-stamp plate 8, which is placed on the press table. The alignment of the pillow with the sub-die plate is provided by the centering sleeve 9. The eyebolts are turned away. Similarly, the upper cushion 13 is attached to the upper sub-stamp plate.

Heated to the calculated temperature stamp 10 is installed on the lower cushion mounted on the lower sub-stamp plate, and is attached to the sub-stamp plates 8 and 11.

The decrease in heat flux on the contact surface of metal surfaces with a thermal conductivity of less than 30 W / m · deg, according to V. M. Popov “Heat transfer in the contact zone of detachable and integral connections” Moscow, Energy 1971 (see page 109), is from 2 to 5% for each contact pair, and for non-metallic materials with thermal conductivity less than 1 W / m · deg up to 10%. Therefore, heat removal from heated dies to sub-stamp plates is difficult and decreases with an increase in the number of contact pairs. However, during stamping, the heat sink increases slightly, thermal expansion of the cushion occurs, especially due to the compression of gaskets made of low-conductivity ceramics. Thus between the heads of the bolts 7, 12 and the ends of the flanges in contact with them, gaps are formed, the size of which is less than the gap "A" (see figure 1). Therefore, the performance of the pillows is not disturbed. The heat transfer from the die to the sub-die plates 8 and 11 through the bolts 7 and 12 is negligible due to their small cross section.

The use of heat-insulating pillows is especially advisable for isothermal stamping of large-sized parts from aluminum and magnesium alloys on large presses. To maintain the temperature of isothermal stamping of multi-ton dies, it is necessary to heat them not only after installing the dies, but also during the stamping process, so the use of pillows can reduce energy costs during operation of the installation.

Since the stamping temperature of aluminum and magnesium alloys does not exceed 400 ... 480 ° C, and the average pressure of isothermal stamping is 30 ... 32 kg / mm ² , for example, sheets of titanium alloy OT4 with a thermal conductivity of less than 15 can be used as a material with low thermal conductivity W / m · hail, thickness from 2 to 6 mm with gaskets made of heat-insulating paper based on silicon, calcium and magnesium oxides 1 mm thick with thermal conductivity 0.25 W / m · hail or fiberglass 0.2… 0.5 mm thick .

The present invention reduces energy consumption and heat loss from the dies to punch plates during operation of the dies due to

- the use of metal sheets with a thermal conductivity of less than 30 W / m · deg, between which flexible gaskets are installed with a thermal conductivity of less than 1 W / m · deg;

- fastening the top sheet with the base with bolts using threaded bushings and flanges, while the base of the pillow and the top sheet have a thickness exceeding the thickness of the intermediate sheets, and are made with grooves for installing threaded bushings and flanges aligned with them with the possibility of axial movement;

- the use of connecting parts of pipes and flanges with the possibility of installing disks with evenly spaced openings.

Claims (2)

1. A heat-insulating pillow for dies, containing metal sheets located between the stamp and the sub-stamp plate, characterized in that the sheets are made of metal with a thermal conductivity of less than 30 W / m · deg, between which flexible gaskets are installed with a thermal conductivity of less than 1 W / m · deg . 2. Pillow according to claim 1, characterized in that the upper metal sheet is fastened to the base of the pillow with bolts using threaded bushings and flanges, while the base of the pillow and the upper metal sheet have a thickness exceeding the thickness of the intermediate sheets between them, and are made with grooves for installation of threaded bushings and flanges aligned with them with the possibility of their axial movement.