RU2227776C2 - Method for making vulcanite-binder abrasive wheels - Google Patents

Abstract

FIELD: manufacture of large-height polishing and grinding wheels. SUBSTANCE: method comprises steps of rolling abrasive mass to sheets; blanking annular semifinished products of rolled abrasive mass; packing them on mandrel of blanking apparatus; compacting prepared pack. Before rolling, abrasive lumpy mass is shaped to round cross section blank by means of worm extrusion process and received round semifinished product is flattened by rolling process. EFFECT: lowered labor consumption, enhanced efficiency of method. 2 dwg

Description

The invention relates to the abrasive industry, namely to the production of preforms of predominantly large-sized circles of high height.

A known method for the production of blanks of grinding wheels on a volcanic bond, including rolling abrasive lumpy highly porous masses on sheets with a height of 6-13 mm, cutting from them ring semi-finished products, assembling them into piles on a table of a cutting press, transferring piles to the packaging section, assembling packages from piles to the mandrel of the lower molding plate, transferring the bags to the pressing section and sealing the bag by pressing in the mold [1]. In this way, grinding and polishing wheels are obtained predominantly with an outer diameter of 200 to 500 mm and a height of 50 to 250 mm.

The main disadvantages of this method are the high complexity, low quality sheets and pressed blanks and a large percentage of return and irrecoverable losses.

The high complexity of the method is due to the high complexity of the rolling operations from the abrasive mass of the sheets, as well as the manual operations of assembling the stacks, transferring them to the packaging section, assembling the packages and transferring them to the pressing section.

The low quality of the sheets is associated with the formation of flaws and cracks on the lateral edges of the sheets during rolling, and the low quality of pressed blanks is associated with the formation of delaminations in the contact planes of the ring semi-finished products.

A large percentage of recyclable waste (over 30% of the mass of sheets goes into the flake when cutting annular semi-finished products) is associated with the presence of tears and cracks on the lateral edges of the sheets, and a large percentage of irrevocable waste (scrap of blanks reaches up to 50% of their total mass) is mainly connected with the contamination of the surfaces of the ring semi-finished products in the manual operations of assembling stacks and packages and the formation of delays at their contact during pressing.

The closest in technical essence and the achieved result to the proposed method is a method for the production of abrasive wheels on a volcanic bond, including rolling from a lump of abrasive mass of a sheet, cutting annular semi-finished products from it, packing them on a mandrel of a cutting device and compressing the packet by pressing each subsequent felled annular semi-finished product to previous [2].

This method of manufacturing abrasive wheels reduces laboriousness by eliminating the manual operations of assembling piles and bags, as well as the operations of transporting them. To improve the quality of pressed blanks by eliminating the contaminating surfaces of the ring semi-finished products of manual operations, and to reduce marriage by bundles to almost zero.

However, the method still has other significant drawbacks consisting in the high complexity of the sheet rolling operations, the low quality of the sheets and the large percentage of returnable waste.

The high complexity of the operations of the sheet rolling process is associated with the performance of multi-pass rolling on a single-cage mill. In the first pass, a semi-finished sheet is rolled from a lump of highly porous abrasive mass. This semi-finished product does not have a predetermined density, defects are formed on its surface in the form of voids and unformed sections, so a flat roll is manually folded from the semi-finished sheet by hand and again set into the mill rolls. These operations are repeated at least three times.

Low quality sheets, i.e. the presence of flaws and cracks on the lateral edges of sheets is explained by the low plastic properties of the volcanic mass containing up to 70% of abrasive grains, as well as its free flow during rolling in sheet width directions.

A large percentage of recyclable waste in the form of outer lining of ring semi-finished products is associated with defects on the edges and near the edges of the sheets.

The objective of the invention is to reduce the rolling passes, the elimination of surface defects of the sheets due to the favorable stress state circuit upon receipt, reduction of return waste.

The problem is achieved in that in the known method for the production of abrasive wheels on a volcanic bond, including rolling sheets from an abrasive lump, cutting annular semi-finished products from them, packing them on a mandrel of a cutting device and subsequent sealing of the bag, according to the invention, they are shaped before rolling the abrasive lump round cross-section by worm extrusion, and rolling rounding out the conditioning of this round semi-finished product under the condition S _cr = (1.10-1.15) D _to h _l , where S _cr - area a cross-section of a round semi-finished product equal to the cross-sectional area of the sheet S _l ; D _to - the diameter of the cut from the sheet of the ring semi-finished product; h _l - the height of the sheet, equal to the height of the annular semi-finished product h _to .

The transformation of the lump mass into a semi-finished product of circular cross section by means of screw extrusion significantly reduces the complexity of sheet production by reducing the rolling passes. In the proposed method, the sheet is obtained by one operation of screw extrusion and single-pass rolling. Compared with the known method, in which four-pass rolling with manual operations is carried out in three passes of assembly of flat rolls from sheet semi-finished products and feeding them to the mill rolls, the number of forming operations is halved.

Since the semi-finished product of circular cross section is extruded under the action of a stress circuit with comprehensive compression, defects on its surface do not arise. Subsequent flattening of the round semi-finished product by rolling also does not lead to the formation of flaws and large macrocracks. When flattening, only individual minor defects and microcracks occur on the lateral edges of the sheets.

Improving the quality of the sheets allows you to reduce the return waste going into the external environment, after the cutting of the ring semi-finished products.

When the cross-sectional area of the round semi-finished product and the sheet is S _cr = S _l <1.10 D _to h _l, defects in the form of microcracks may appear on the ring semi-finished products cut from the sheet. When the cross-sectional area of the round semi-finished product and the sheet S _cr = S _l > 1,15 D _to h _l when cutting annular semi-finished products, the percentage of waste in the form of an external layer increases.

The proposed method is illustrated in figures 1 and 2, where figure 1 shows a diagram of a screw extrusion and rolling, figure 2 is a view along arrow A for rolled and semi-finished after extrusion.

The proposed method is as follows.

The abrasive mass is fed into the loading device of the screw extruder (not shown). Rotating the worm 1, the lump mass 2 is crushed, mixed, compacted and moved along the arrow V _e relative to the body of the extruder 3. At the exit from the housing 3, the mass 2 enters the extrusion zone formed by the profile head 4.

In the head, the mass is deformed according to the all-round compression scheme and gives it the shape of a semi-finished product 5 of circular cross section. After this, the semi-finished product 5 is set in the rolling rolls 6 and lead its conditioning, receiving sheet 7.

The proposed method was tested in ZAO “Rossi”. In an extruder with a worm diameter of 150 mm and a working case length of 1500 mm, a round semi-finished product with a diameter of d _e = 54 mm was obtained from the abrasive mass of grade 14A 10-N ST B. This round semi-finished product is flattened in one pass of rolling into a sheet with a height of h _l = 10 mm and a width of b _l = 226 mm. There were no tears or cracks on the lateral edges of the sheet. Ring semi-finished products with an outer diameter of D _k = 205 mm were cut from a sheet, intended to produce a grinding wheel with an outer diameter of 200 mm, a height of 100 mm and an opening diameter of 127 mm.

Thus, the cross-sectional area of the sheet S _l = S _cr exceeded the area D _to h _k intended for cutting circular semi-finished products by 1.10 times, i.e. return losses in the cloud reduced by more than 2 times.

The proposed method is expediently used in the production of high (more than 50 mm high) grinding and polishing wheels on a volcanic bond.

Sources of information taken into account:

1. Technological instructions for the manufacture of volcanic and flexible polishing wheels. Chelyabinsk, South Ural Central Scientific Research Institute, 1970, S.4-60.

2. RF patent №2107609 M. Cl ⁶ . B 24 D 18/00. A method of manufacturing an abrasive tool and a device for its implementation, from 03/27/98.

Claims (1)

A method of manufacturing abrasive wheels on a volcanic bond, including rolling abrasive lump into sheets, cutting annular semi-finished products from them, packing on the mandrel of a cutting device and subsequent sealing of the bag, characterized in that before rolling the abrasive lump mass they give a round cross section by worm extrusion, and rolling perform the conditioning of this round semi-finished product, provided S _cr = (1.10-1.15) D _to h _l , where S _cr - the cross-sectional area of a round semi-finished product, equal to the cross-sectional area of the sheet S _l ; D _to - the diameter of the cut from the sheet of the ring semi-finished product; h _l - the height of the sheet.

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