RU2180284C2 - Method of producing abrasive tool - Google Patents

Abstract

FIELD: producing grinding and polishing wheels based on vulcanite binder. SUBSTANCE: method includes rolling the vulcanite forming abrasive mixture into plates, cutting-out annular workpieces from the plates, assembling them into a set on the rod, and preliminarily pressing without die block with the force of 0.1-0.2 from the force of final pressing. Finally the wheel is pressed in a die by means of molding plates. Spacers of vulcanite mass without abrasive grains are interposed between set and plates. Size of the spacers is determined from equality of their volumes before and after final pressing. EFFECT: enhanced quality and strength of abrasive wheels. 2 dwg

Description

 The invention relates to the abrasive industry, namely the manufacture of grinding and polishing wheels on a volcanic bond.

 A known method of manufacturing an abrasive tool on a volcanic bond with an outer diameter of more than 250 mm, a height of more than 100 mm, including preparing the abrasive mixture, rolling the mixture into plates, cutting rings out of them, a set of rings of a bag consisting of 12-30 or more rings, subsequent pressing of this package in the mold on the press and vulcanization of the compacts [1].

 The disadvantage of this method is the intense barrel formation during the pressing process as a result of significant friction forces arising on the contact surfaces of the molding plates and the package of ring blanks, which leads to inhomogeneous deformation and does not allow to obtain an equal density pressing along the height, there are also gaps on the side surface of the pressed circle and delamination on the contact planes of the individual rings.

 The closest in technical essence and the achieved effect to the proposed one is a method of manufacturing an abrasive tool, in which they take a volcanic molding abrasive mixture, roll it into plates, cut annular blanks from the plates, which are assembled into a bag on a rod, after which the bag is pre-compacted without a matrix with a force of 0.1-0.2 of the final pressing force in the mold [2].

 This method significantly reduces the possibility of splitting caused by air sealing on the contact surfaces of the rings, but the phenomenon of barrel formation and the associated inhomogeneity of deformation, different density of the workpiece in height, which reduces the quality of the circles and their strength, are preserved. With this method, significant energy costs in the operations of pressing and extruding the workpiece from the matrix.

 The problem solved by the invention is the elimination of barrel formation by changing the direction of the vector of the active friction forces on the contact surfaces of the tool with the package and thereby improving the quality and strength of the abrasive tool, as well as reducing energy costs for pressing operations.

The problem is achieved in that in the method of manufacturing an abrasive tool, in which a vulcanite molding abrasive mixture is rolled into plates, annular blanks are cut out of them, they are assembled into a bag on a rod, and the bag is pre-compacted without a matrix with a force of 0.1-0 , 2 of the magnitude of the final pressing force, and the final pressing of the circle in the mold using molding plates, use annular gaskets made of a volcanic mass that does not contain abrasion grain, placed between the package and the molding plates, the size of the gaskets is determined from the condition of equal volumes V and V _1, respectively, before final pressing and after, taking into account the precipitation of each gasket by an amount not exceeding half the allowance for the height of the pressed circle and the size of it outer and inner diameters, while
V = 0.25π (D ² -d $\genfrac{}{}{0ex}{}{\text{2}}{\text{vn}}$ ) h,
where D _n and d _EX = (d + 0,75b) - respectively, the outer and inner diameters of the annular gasket,
h is the height of the gasket equal to the height of the annular workpiece;
d and b are the inner diameter and width of the pressed tool, respectively.

V ₁ = 0.5h ₁ F _fc ,
where h ₁ and F _fc - respectively, the allowance for height and the area of the annular surface of the extruded circle.

The fact that they use ring gaskets made of a volcanic mass that does not contain abrasive grain, placed between the bag and the molding plates, and the size of the gaskets is determined from the condition that their volumes are equal to V and V _1, respectively, before final pressing and after, taking into account the precipitation of each gasket on a value not exceeding half the allowance for the height of the pressed circle and the size of its outer and inner diameters, while
V = 0.25π (D $\genfrac{}{}{0ex}{}{\text{2}}{\text{n}}$ -d $\genfrac{}{}{0ex}{}{\text{2}}{\text{vn}}$ ) h,
where D _n, d _ext = (d + 0,75b) - respectively outer and inner diameters of harvested annular gasket;
h is the height of the annular gasket equal to the height of the annular blank;
d and b are the inner diameter and width of the pressed tool, respectively.

V ₁ = 0.5h ₁ F _fc ,
where h ₁ and F _fc - respectively, the allowance for the height and the area of the annular surface of the moldable circle, will allow you to change the friction conditions on the contact surfaces of the tool - the workpiece, reduce the friction coefficient on these surfaces to a sufficient minimum and thereby prevent significant barrel formation starting from the very beginning of the pressing process, to create a uniform stress-strain state in the moldable circle and to increase the uniformity of the circle in height, reduce energy costs. Elimination of significant barrel formation during the pressing process creates favorable conditions for the unhindered removal of air from the limits of the mold volume, which will help to eliminate the delays caused by this reason, and thereby avoid the need for a bagless preliminary pressing of the bag.

 The restriction of the settlement of each of the annular gaskets to a value corresponding to half the allowance to the height of the formed circle and to the size according to its outer and inner diameters, i.e. prior to contact with the matrix wall, it will allow for subsequent machining to remove the remaining layer of the volcanic mass at a lower cost than peeling the vulcanized abrasive volcanic mass and to minimize the flow of excess volcanic mass into the gap between the upper molding plate and the matrix wall.

 Figure 1 shows the package installed in the mold before pressing, figure 2 - package in the mold after pressing.

 In figure 1, 2 are indicated: 1 - rod, 2 - lower molding plate, 3 - ring matrix, 4 - lower ring gasket, 5 - package assembled from ring blanks, 6 - upper ring gasket, 7 - upper molding plate, 8 - molded circle, 9, 10 - the upper and lower planes of the package.

 The method is as follows.

 Pre-made ring gaskets 4 and 6 of a volcanic mass that does not contain abrasive grain, the size of which is determined by the relationships given in the description. Then, on the lower molding plate 2 mounted on the rod 1, which are installed in the annular matrix 3, lay the lower annular gasket 4 and on the rod 1 collect a package 5 of annular blanks, which lower plane 10 rests on the said gasket 4. After assembling the package on it the upper plane 9 install the upper annular gasket 6 and cover it with the upper molding plate 7. Next, the force necessary to obtain a pressed abrasive wheel 8. is applied to the upper molding plate 7. After the presses are finished Nia carried ejection circle 8 of compacted annular array 3.

According to the proposed method were made grinding wheels on a vulcanite bond with an outer diameter of 500 mm, an inner 305 mm and a thickness of 250 mm. The pressing bag was composed of 25 ring blanks. The thickness of one workpiece averaged 12 mm. The height of the annular gasket was taken equal to the annular billet, which allowed rolling the original plates of various compositions on the same equipment without its readjustment. The inner diameter d _ext annular gasket was set at 378 mm, and an outer _n D - 455 mm according to the given formula. Initially, to control the change in the shape and size of the deposited bag during the pressing process, step-by-step pressing was performed with the pressing removed from the die after each pressing step until the side surface of the bag contacted the die wall. A visual review of pressed blanks at various stages of pressing did not establish the presence of a barrel. When using a measuring tool, it was possible to establish that the size of the barrel did not exceed 0.2-0.3 mm.

 The proposed method is advisable to use in the abrasive industry in the production of grinding and polishing wheels on a volcanic bond.

Sources of information
1. Abrasive materials and tools. Directory. / Ed. V.A. Rybakova. - M.: Research Institute for Engineering, 1976, p. 197.

 2. RF patent 2096166. A method of forming an abrasive tool. In 24 D 18/00. Publ. BI 32.11.11.97.

Claims (1)

A method of manufacturing an abrasive tool in which a vulcanite molding abrasive mixture is rolled into plates, annular blanks are cut out of them, assembled into a bag on a rod, and the bag is pre-compacted without a matrix with a force of 0.1-0.2 of the value of the final pressing force , and the final pressing of the circle in the mold using molding plates, characterized in that they use annular gaskets made of a volcanic mass that does not contain abrasive grain, between the bag and the molding plates, the size of the gaskets is determined from the condition that their volumes are equal to V and V _1, respectively, before the final pressing and after, taking into account the precipitation of each gasket by an amount not exceeding half the allowance for the height of the pressed circle and the size of its outer and inner diameters, while
V = 0.25π (D $\genfrac{}{}{0ex}{}{\text{2}}{\text{n}}$ -d $\genfrac{}{}{0ex}{}{\text{2}}{\text{vn}}$ ) h,
where D _n and d _EX = (d + 0,75b) - respectively, the outer and inner diameters of the annular gasket;
h is the height of the annular gasket equal to the height of the annular blank;
d and b are the inner diameter and width of the pressed tool, respectively;
V ₁ = 0.5h ₁ F _fc ,
where h ₁ and F _fc - respectively, the allowance for height and the area of the annular surface of the pressed circle.

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