US2176481A - Apparatus for producing ground and polished glass strip - Google Patents

Description

Oct. 17, 1939. B WALDRQN AL 2,176,481

APPARATUS FOR PRODUCING GROUND AND POLISHED GLASS STRIP Original Filed March 4, 1958 2 Sheets-Sheet 1 Mmvrwm F. B. WALDRON El AL Oct. 17, 1939.

APPARATUSFOR PRODUCING GROUND AND POLISHED GLASS STRIP Original Filed March 4, 1938 2 SheetsSheet 2 hwmrwrs Patented Oct. 17, 1939 UNITED STATES PATENT OFFICE APPARATUS FOR PRODUCING GROUND AND POLISHED GLASS STRIP Liability Acts Application March 4, 1938, Serial No. 193,908

Renewed August 10, March 10, 1937 4 Claims.

This invention relates to the simultaneous grinding and polishing of both sides of a continuous strip of glass, and has for its object an improved method and apparatus for maintaining the grinding and polishing tools central relatively to the strip.

In the type of apparatus to which the invention relates, the rotary grinding tools are provided with grooves through which the abrasive passes from the centre towards the periphery, but the periphery is formed with a continuous ring which is in contact throughout with the glass; this peripheral ring prevents the rapid escape of the abrasive under the action of centrifugal force.

Now it has been found impracticable to produce a continuous strip of glass so straight laterally, that, while driven through the grinding and polishing apparatus (constituted bya large number of grinding and polishing tools operating on the upper and under surfaces of the strip), it remains central relatively to the tools. If the strip, at any point, deviates from the central position by more than a certain amount, the abovementioned peripheral ring reaches beyond the edge of the strip on one side, and there is then nothing to prevent the abrasive in the grooves from being thrown outwardly from them. The result is that the tool is insufliciently provided with abrasive and ceases to operate effectively.

In the case of polishing tools, which consist usually of felt covered discs rotatably mounted at a plurality of points on a rotating frame, the outermost discs have to overlap the edges of the strip in order that effective polishing may be obtained. If, however, the overlap exceeds a certain amount the surfaces of the discs become injured by the edges of the glass and are no longer in the condition in which they produce effective polishing.

If, therefore, the strip deviates from its central position by more than a certain amount, the discs overlap the edges insufficiently at one side and too much at the other, and are in consequence injured.

In our co-pending application for Letters Patent of even date herewith we have described a device whereby, when the strip deviates from its central position force is applied to it to bring it back to its central position. This device has been found effective so long as the deviations of the strip are small, but, in practice, the deviations are such that, if sufficient force is applied to the strip to bring it central, it is liable to break.

According to the invention, the tools are car- 1939. In Great Britain ried on frames which are adapted to slide transversely of the strip, and means are provided for slidably moving the said frames, so that the two tools of a pair of tools are moved simultaneously and equally, transversely of the strip. Pref- 5 erably, the frames are moved by a motor and a, switch is operated directly or indirectly by a transverse movement of the strip, and a hunting gear is provided to operate the motor to move the said frames in the same direction as the movement of the strip and by approximately the same amount.

In the accompanying drawings:

Figure 1 is a plan View of one grinding tool of a grinding apparatus, with its accompanying framework;

Figure 2 is a vertical section thereof along the line A-A of Figure 1;

Figure 3 is a view from the left hand side of Figure 1; and

Figure 4 is a diagrammatic view of a step by step switch circuit.

The strip of glass l is driven through the apparatus by pairs of rollers not shown. It is ground between pairs of grinding tools 2, of which there are fifteen to twenty, and these are followed by a larger number of polishing tools, when the strip is polished in the same apparatus. The shafts 3 of the tools are rotated (by means not shown) in bearing blocks 4, which are adapted to slide in frames 5. Means, not shown, are provided for raising and lowering the tools in the frames 5. The frames 5 rest on rectangular frames 6, and the lower frames 5 on rectangular frames 1.

The supporting framework of the apparatus consists of vertical box columns 8 which support transverse box girders 9 and longitudinal box girders ID. The girders I 0 which continue to the left of Figure l are omitted. The transverse girders 9 carry slides II on which the rectangular frames 6 rest and can slide, and slides l2 are fixed to the lower ends of the column 8 on which the rectangular frames 1 rest and can slide. The tools 2 can therefore be moved transversely of the strip of glass I by the sliding of the frames 6 and I on the slides II and I2.

The means for moving the tools transversely are as follows: Two nuts 13 are fixed to the frame 6, one near each end, and two nuts M- to the frame 1. Screws l5 and I6 engage the nuts l3 and I4 respectively and carry bevel wheels l1 and I8 respectively. The two bevel wheels I! are connected together by bevel wheels IS on a shaft 20 in the longitudinal girder ID. The shaft 20 also carries bevel wheels 2| which engage bevel 55 wheels 22 on two vertical shafts 23 in the columns 6. The vertical shafts 23 carry at their lower ends bevel wheels 24 which drive the bevel wheels I 8 on the screws l6 through bevel wheels and a shaft similar to the bevel wheels 2| and I9 and shaft 26. By the above-described gearing, the four screws l5 and I 6 are turned simultaneously on turning the shaft 20, and thereby the frames 6 and 1, carrying the tools 2, are moved transversely together, and always remain coaxial.

The screws may be turned by a hand wheel geared to the shaft 20, but preferably they are turned by a motor connected to an automatic device. The motor 25 turns a worm wheel 26 on a shaft 21 which carries a bevel wheel 28 engaging the bevel wheel l9. When the edges of the strip are cut before the strip enters the grinding apparatus, the location of the strip is conveniently ascertained by one edge of it, and Figures 1 to 3 show a device whereby the motor 25 is turned in one direction or the other so as to maintain the axis of the tools 2 always at a fixed distance from one edge of the strip. Thereby, when the strip is cut to constant width, the axis of the tools may be maintained over the centre line of the strip whatever may be the position of the strip in a transverse direction.

A roller 29 (Figures 2 and 3) on the arm 30 of a lever pivoted at 3| to a bracket 32, is pressed against the edge of the strips l by a spring 33 attached to the other arm 34 of the lever. The arm 34 is connected by a link 35 to the arm 36 of a lever pivoted at 31. The other arm 38 of this lever is forked to engage the arm 39 of a relay reversing switch 40 so connected to the motor 25 that a movement of the arm 39 in one or the other direction causes the motor 25 to turn in one or the other direction.

In operation, if the strip l moves to the right (as seen in Figure 3) pressing the roller 29 to the right, the forked arm 38 moves to the right; this moves the arm 39 of the switch 46 to the right, closing the motor circuit to turn the motor so that the screws l5 and I6 turn righthandedly. Thereby, the frames 6 and I are moved to the right, and, since the frame 6 carries the switch 40, this also moves to the right until the arm 39 breaks the motor circuit. In this way. the tools 2 carried by the frames 6 and I are caused to follow the transverse movement of the strip. The arm 39 is conveniently given play in the fork of the arm 38, so that small unimportant movements of the strip can occur without causing movement of the tools. The above is one form of the device commonly termed a hunting gear, in which one member is caused to follow any movement of another member. Another form is shown diagrammatically in Figure 4, in which 4| and 42 are switch arms turned by movement of the strip and of the tool frame respectively. Each switch arm has a series of contacts, such as a, b, c, A, B, C, connected as shown, and the two arms are connected to the mains through the armature 43 of the motor 25. In the position shown, the circuit is open; if the strip moves to turn the arm 4| to contact B, the circuit is closed, and the motor turns to move the tool frame, and the arm 42 to contact 12, when the circuit is broken.

Similarly, a further movement of arm 4| to contact C closes the circuit which is opened again when arm 42 is moved to contact 0. The arm 42 follows the arm 4| also in the other direction, provided that the motor is reversed. This is effected as follows: a second arm 44 is mounted friction-tight on the spindle of the arm 4| and is adapted to make contact with one of the two contacts 45 which are connected as shown to the relay coils 46 of a reversing switch 41, adapted to reverse the current through the shunt 48 of the motor. From the position shown, a movement to the left of the switch arm 4| carries with it the arm 44, to make contact with the left hand contact 45, to reverse the motor shunt field. The arm 44 remains in this position during any subsequent movement of the arm 4| in the same direction, but reverses the motor field on a reverse movement of the arm 4|.

In our above-mentioned co-pending application for Letters Patent, devices are described which are adapted to ascertain the location of the strip with reference to its centre line, when the edges of the strip are not cut, and cannot, therefore, be used to determine the location of the strip. Any such device, which moves correspondingly to the centre line of the strip, may be used to move the switch arm 4|, or the appropriate part of any other hunting gear, instead of the roller 29 hearing against the edge of the strip.

Having described our invention, we declare that what we claim and desire to secure by Letters Patent is:

1. Apparatus for operating on a continuous strip of glass which is passed longitudinally through the apparatus, comprising a plurality of pairs of tools operating simultaneously on the upper and lower surfaces of the strip, with the two tools of each pair opposite one another, frames adapted to carry the tools and supports above the strip for the frames of the tools operating on the upper surface and supports below the strip for the frames of the tools operating on the lower surface, slideways on the supports transversely of the apparatus on which the frames are adapted to slide, means for holding the frames on the slideways in a predetermined operative transverse position relatively to the supports and to the strip, and means, operable when the strip moves transversely, for moving the frames to an operative position which is different relatively to the supports but substantially the same relatively to the strip.

2. Apparatus for operating on a continuous strip of glass which is passed longitudinally through the apparatus, comprising a plurality of pairs of tools operating simultaneously on the upper and lower surfaces of the strip, with the two tools of each pair opposite one another, frames adapted to carry the tools and supports above the strip for the frames of the tools operating on the upper surface and supports below the strip for the frames of the tools operating on the lower surface. slideways on the supports a transversely of the apparatus on which the frames are adapted to slide, means for holding the frames on the slideways in a predetermined operative transverse position relatively to the supports and to the strip, and means, set into operation by a lateral movement of the strip, for moving the frames to an operative position which is different relatively to the supports but substantially the same relatively to the strip.

3. Apparatus for operating on a continuous strip of glass comprising a plurality of pairs of tools operating simultaneously on the upper and lower surfaces of the strip, with the two tools of each pair opposite one another, frames adapted to carry the tools and supports above the strip for the frames of the tools operating on the upper surface and supports below the strip for the frames of the tools operatingvon the lower surface, slideways on the supports transversely of the strip on which the frames are adapted to slide, a motor connected by gearing with the two frames carrying the tools of a pair, a switch operated when the strip makes a transverse movement and a hunting gear comprising the said switch adapted to operate the motor to move the said frames in the same direction as the movement of the strip and by approximately the same amount.

4. In a glass grinding apparatus including a plurality of grinding tools arranged to operate simultaneously on both surfaces of a continuous strip of glass passing through the apparatus, the combination of means for shifting the grinding tools laterally, relatively to the strip to maintain the strip and grinding tools in centralized relation during the grinding period, and automatic means for controlling the operation of said shifting means to correct for any deviation from said centralized relation.

FREDERIC BARNES WALDRON.

FRANK EDWIN SIDCOMBE.

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