SU1729783A1 - Process for manufacturing products from expanding granules - Google Patents

Abstract

Usage: technology of making tubular seamless shells for coating paint-roller rollers. SUMMARY OF THE INVENTION: After compaction in the form of a granule based on foaming vulcanizing polyethylene, it is heated at a temperature of 20-40 ° C below their melting temperature until it is fully heated. Cooled at 18-20 ° C. After sintering, it is re-cooled at 10-20 ° C. The preform is removed from the mold and the outer layer is removed. The processed billet is foamed freely and cured on a metal gauge. 1 tab., 2 Il.

Description

The invention relates to a method for processing foaming granules to obtain tubular seamless shells by the pressing method and can be used in various industries, in particular for the production of lining shafts of dyeing machines in the furniture industry.

The closest to the present invention is a method of manufacturing products from an expandable thermoplastic composition, including compaction of the composition in the form, sintering, cooling, removal of the workpiece, its mechanical processing, subsequent foaming in the form. According to the configuration and size of the finished product, and curing intended to obtain floats.

However, this method cannot be applied to obtain large-sized seamless shells (outer diameter of the coating 200-300 mm, length up to 1500 mm, coating thickness up to 50 mm) due to the peculiarities of their structures and the requirement for the quality of the internal structure of the foam material products.

The purpose of the invention is to improve the quality of products with a central hole and the expansion of technological capabilities.

The goal is achieved by the fact that according to the method of manufacturing products from foaming granules based on vulcanizing polyethylene, including molding the workpiece by compacting the granules in a mold, sintering in a heat transfer medium and cooling, removing the blank, machining it and then foaming, the compacted granules are further heated before sintering at a temperature below their melting temperature by 20–40 ° C until complete heating, followed by cooling to room temperature, mechanical processing Application is accomplished by removal of its outer layer, and then carried out after free foaming with (L

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blowing curing on a metallic caliber.

The proposed method was implemented in the manufacture of tubular seamless pneumopolyethylene shells with dimensions of 250x165x1500 mm for rolls of paint-spreading machines used in the furniture industry for applying primer coatings and water-soluble dyes.

FIG. 1 shows a form for sintering blanks; in fig. 2 - shaft with a sheath of foamed workpiece.

The form is made detachable and contains a cylindrical body 1 located along the central axis of the form core 2, a cover 3, an insert 4 made in the form of a glass for pressing the material.

The housing 1, the core 2 and the insert 4 form the shaping cavity of the workpiece 5. The insert 4 is held in the housing with the aid of a collar 6.

The casing 7 is installed with a tension on the metal paint roller 8.

Example 1. In a mold cavity for sintering, pour a polyethylene composition of foaming vulcanizing brand 108-58P (TU 6-06-1753-79) or 108-59A (TU 6-54.0203492-30-89) in the form of granules with a bulk density of about 0. , 60 g / cm in the amount of 4.1 kg. An insert 5 is placed into the forming cavity from above and using a press (not shown) with a force of 5 ms, the composition is compacted to a density of 0.74-0.76 g / cm3.

After compaction of the composition with a collar 6, insert 4 is fixed and the mold is placed in a thermal furnace with a temperature of 70-90 ° C, where it is heated for 30 minutes to fully warm the composition, not to allow it to melt (polyethylene melting point is 110 ° C). Temperature control is carried out on the surface of the mold, and the full warm-up time is established experimentally.

At the end of the warm-up period, the form is removed from the thermal furnace and kept in air at room temperature until cooled for 4-5 hours.

Then the mold is again placed in a thermal oven, but already with a temperature of 185 ± 5 ° C and maintained at this temperature for 2-3 hours to sinter the preform. When this occurs, the melting of polyethylene, thermal decomposition of the porophore and dicumyl peroxide, which are part of the composition, and spatial macromolecules are crosslinked.

At the end of the sintering process, the form is removed from the thermal furnace, cooled in air.

Allow it to reach room temperature, decompress and remove the preform. The resulting preform has the shape of a tubular product with dimensions; outer diameter 125. mm,

internal diameter is 80 mm, length is 750 mm.

The outer surface of the tubular billet is machined on a lathe to remove the outer crust and open the pores on the entire outer surface to a depth of 2-5

mm This makes it possible to ensure uniform heating throughout the entire volume of the workpiece at a subsequent stage — the foaming stage.

In addition, the removal of the outer crust of the workpiece provides an intermediate control of the method — control of the operation of sintering the workpiece by the absence or presence of dark spots on the cut characterizing the poorly performed technological

sintering operation. The processed high-quality billet is placed in a thermal furnace heated to 130 ± 5 ° C and held there for 2-3 hours to effect free foaming, as a result of which it increases its size by about 2 times. At the end of the foaming mode, the uncured hot billet is removed from the thermal furnace and freely put on a metal gauge with an outer diameter of 165 mm, then cooled to 20-30 ° C. Cooling foaming, the preform hardens.

After curing, the resulting shell is removed from the gauge and a visual inspection is performed. A quality shell should have a uniform, finely cellular structure without bubbles.

After that, the shell 7 can be supplied to the consumer, where it is pulled on

A metal paint roller 8 is machined to a required diameter on a lathe and polished.

Examples 5-7 (control). The method is performed with foreign values.

the preheating time, while increasing the heating time above the optimum does not affect the quality of sintering and foaming of the workpiece.

Examples 8 and 9 (control). The method is carried out with foreign values of the preheating temperature of the composition.

Examples 10-11 (control). The method is performed with foreign press fitting values.

Example 12 (control). The method is carried out without preheating the compacted composition.

Example 13 (control). The method is carried out without machining the workpiece.

Example 14 (control). The method is performed without using a metal gauge.

Example 15 (prototype). The method is carried out according to the method prototype without preheating the compacted composition at 70-90 ° C, without machining the sintered billet and when foaming in a restrictive form on the outer diameter.

The modes of performing the method of the surface quality of the obtained shells are shown in the table.

The use of the proposed method provides an improvement in the quality of the structure of foamed products, which are characterized by uniformity, fine porosity, the absence of bubbles.

The method is characterized by simplicity of technology and tooling and can be used in specialized industries.

The foamed polyethylene shells obtained by the method used as coatings of paint-roller shafts have extremely good

impregnating ability and are characterized by good resistance to varnishes, paints, organic solvents, which significantly increases the service life of coatings in

in the form of polyethylene shells up to 1 g instead of 2 months. The maintainability of such coatings is improved due to the simplicity of their replacement, and repair is carried out in the conditions of furniture production.

Claims (1)

Invention Formula The method of manufacturing products from expandable granules based on foaming vulcanizing polyethylene, including their compaction in the form, sintering, cooling, removing the workpiece, its mechanical processing, subsequent foaming and curing, characterized in that with the aim of improving the quality of products with a central hole and expansion of technological capabilities, before sintering, compacted granules are additionally heated in the form at a temperature below their melting temperature by 20–40 ° C until complete heating followed by cooling to room temperature, the workpiece is machined by removing its outer layer, after which free foaming is carried out, followed by curing on a metal gauge. Phage. 2