US1956781A - Glass grinding apparatus - Google Patents

Description

Y 1934' F. B. WALDRON GLASS GRINDING APPARATUS Filed Sept. 21, 1933 fi'c'deric iarhes [vi draw 1 W A var/rays Patented May 1, 1934 1,956,781 GLASS GRINDING APPARATUS Frederic Barnes Waldron, Prescot, England, as-

signor to Pilkington Brothers Limited, Liverpool, England, a company of England Application September 21, 1933, Serial No. 690,449 In Great Britain September 22, 1932 2 Claims.

This invention relates to glass grinding apparatus and has for its object means for forcing the abrasive towards the glass.

In glass grinding apparatus in which the grinding tool does not operate on the upper surface of horizontally placed fiat glass, as, for example, in apparatus in which the two surfaces of flat glass are ground simultaneously, it has been found dimcult to maintain a supply of abrasive, (comld monly sand and water) between the grinding surface and the glass.

The grinding tool commonly used is a rotating disc provided with nogs or blocks of cast iron generally of rectangular form.

According to the present invention, each block has its leading face inclined to the radius forwardly (in reference to the direction of rotation) and outwardly, and also forwardly away from its operative surface.

In the accompanying drawing:- Figure l is a plan [(partly broken away) of the operative surface of'a grinding tool according to the invention;

Figure 2 is a section thereof along the line 22 of Figure 1;

Figure 3 is a section along the crooked line 3-3 of Figure 1;

Figure 4 is a diagrammatic plan showing a single block; and

Figure 5 is a perspective view of Figure 1, looking down at an angle of to the horizontal. The circular disc 1, with operative surface 2, commonly made in cast iron, is attached to the flange 3 of the tool. The disc 1 has a central aperture 4, surrounding which, is an annular channel 5 with an approximately central web 11. Outside this channel 5, is the operative surface 2, which is divided into three rings by two circular grooves 6. Of these three rings, the two inner ones are divided up into blocks or-nogs 7 by grooves 8, while the outer ring has similar grooves 8 which do not, however, extend tothe periphery of the disc 1.

Assuming the disc 1 to rotate in the direction of the arrows shown in Figures l and 5,. the

grooves 8 are inclmed to the radii outwardy and forwardly in the direction of rotation, as seen in Figurel." 'rFur-ther, the grooves are inclined to the surface oi' gthe disc, as shown in Figure 3, the

inclination being"3forwardly away from the operative surface, that is to say, forwardly and downwardly in the tool shown.

Abrasive (commonly sand and water) is supplied through the hole 9 to the central aperture 4 65 and passes below the inner wall 10 of the channel 5. Apertures 12 in the web 11 (only one such aperture is represented in Figure 1) permit the abrasive to rise into the upper part of the channel 5, and from this the abrasive is forced outwardly along the grooves 8 by centrifugal force.

By reason of the inclination of the grooves, the abrasive, in moving outwardly under centrifugal force, tends to move upwardly towards the operative surface. Referring to Figure 4, which shows a single block, with operative surface 2 and inclined surface 13 formed by the inclined groove 8, imagine a pxrticle of abrasive C. The centre of the tool being at O, the particle is acted on by centrifugal force in the direction of CD, and by gravity downwards from the paper. If the particle were able to move in the direction CD, it would be accelerated in moving outwardly, because its velocity would increase with its radius. If it moved along the bottom of the groove, in the direction CE, its motion would be still further accelerated. The particle can be accelerated in its circular motion only by pressure exerted on it by the surface 13 and, since this is inclined, the pressure has an upward vertical component, which, by suitable choice of inclinations and 30 speeds, can be sufficient to overcome the downward force of gravity.

The particle, in fact, will tend to move along a path such as CF, in which its motion is not accelerated, and this path brings it from the bot- 35 tom of the groove to the operative surface.

The essential feature of the invention therefore lies in each block '7 having its leading face 13 inclined to the radius outwardly and forwardly and forwardly away from its operative surface. The leading faces 13 are shown shaded in Figure 5.

The tool described above, gives blocks of this form and can be conveniently manufactured from a disc of cast iron. The tool, however, may be constructed by bolting blocks on to a fiat disc. The circular grooves 6 do not form an essential part of the invention, but it is preferable for the sake of better distribution, that the inclined grooves 8 should be connected by cross grooves.

The circular grooves 6 or other cross grooves may be so inclined, that the inner face of each block is inclined inwardly away from the operative surface, so that the centrifugal force acting on the abrasive against the inner faces, tends to move it towards the operative surface. The abrasive is not, however, so readily engaged between the operative surface and the glass, as when it is brought to the surface at the leading faces of the blocks. 1

The inclination of the leading faces of the blocks to the radii, is preferably made greater, the greater the distance of the block from the centre.

The invention is particularly applicable to glass grinding apparatus operating on the underside of the glass, when gravity tends to keep the abrasive the leading face of each block being inclined both to the radius and to the operative surface, the inclination to the radius being such that as the radius increases the face extends from the radius in the direction of rotation and the-inclination to the operative plane being such that portions away from the operative surface are further forward than portions nearer to the operative surface.

2. In glass grinding apparatus a grinding runner having its operative surface formed into blocks by grooves in a disc adapted to lead the abrasive outwardly and cross-connecting grooves, the first mentioned grooves being inclined to the radii forwardly and outwardly and also inclined to the operative surface in a direction forwardly away from the surface.

FREDERIC BARNES WALDRON.

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