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(11) | EP 0 451 333 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Apparatus for grinding the edge of a glass sheet |
| (57) The invention relates to an apparatus for grinding the edge of a glass sheet, said
apparatus comprising a substantially horizontal glass sheet carrying table, a rotatable
drive shaft (7), a grindstone (1) attached to drive shaft (7) and having its periphery
formed with one or more V- or U-shaped grooves (2), said grindstone (1) being adapted
for vertical movement relative to the plane of a carrying table. Drive shaft (7) is
surrounded by a tubular axle (8) rotating therealong and rotatably journalled (9)
to a body (6), said drive shaft (7) being axially shiftable inside the axle. The end
of drive shaft (7) opposite to grindstone (1) is through the intermediary of a rotary
joint (13) engaged by adjusting means (14-18) for adjusting the axial position of
drive shaft (7) relative to body (6). Thus, the transmission of rotating power to
the drive shaft can be effected from a driving motor which is stationary in a constant
position. |
[0001] The present invention relates to an apparatus for grinding the edge of a glass sheet, said apparatus comprising a substantially horizontal glass sheet carrying table, a rotatable drive shaft, a grindstone attached to the drive shaft and having its periphery formed with one or more V- or U-shaped grooves, the grindstone being adapted for vertical movement relative to the plane of the carrying table. This type of apparatus is known e.g. from DE patent publications 2 127 298 and 3 706 886. In the latter, a grindstone along with its driving motor is vertically movable, whereby the masses to be moved are great and the adjustment accuracy suffers. On the other hand, in Patent publication DE 2 127 298 a glass sheet is supported between ball-coated plates and the plates are adjustable relative to a framework. Also in this case the adjustment necessarily involves the movement of great masses and the adjustment is slow and tedious to perform.
[0002] An object of the invention is to provide an apparatus adapted for the vertical adjustment of a grindstone, wherein the masses to be moved are small and which provides for a high adjustment precision and whereby the adjusting movements can be performed readily and quickly.
[0003] This object is achieved by means of the invention on the basis of the characterizing features set forth in the annexed claims.
[0004] One embodiment of the invention will now be described in more detail with reference made to the accompanying drawings, in which
- fig. 1
- is a schematic side view of the requirement for vertical adjustment of a grindstone with varying glass thickness.
- Fig. 2
- shows schematically the requirement for vertical adjustment of a grindstone when using different grinding grooves of the same grindstone for glasses of varying thickness.
- Fig. 3
- is a vertical section of the structural design of an apparatus of the invention, and
- fig. 4
- is a vertical section of the enlarged detail IV in fig. 3.
[0005] Referring to fig. 1, reference numeral 1 designates a grindstone having its periphery provided with a V-shaped grinding groove 2. A glass sheet 3 or 4 is carried on a table 5 which is stationary in vertical direction. By displacing grindstone 1 in vertical direction, the plane of symmetry of grinding groove is brought to coincide with the centre line of the edge of glass sheet 3 or 4. This is followed by moving grindstone 1 or table 5 in horizontal direction until the rim edges of glass sheet 3 or 4 come to contact with the flanks of grinding groove 2. Grindstone 1 is rotated around the vertical axis while moving it along the edge of glass sheet 3 or 4. Alternatively the table is moved in horizontal direction. Grinding table 5 may also rotate. As grindstone 1 is rotating, the sharp edges of glass sheet 3 or 4 are being symmetrically ground. The thickness of glass sheet 4 is e.g. 2 mm and the thickness of glass sheet e.g. 2,5 mm.
[0006] As the thickness of a glass sheet changes, a grindstone 1 is moved in vertical direction, i.e. in the direction orthogonal to the plane of the glass sheet, either upwards to a position II or downwards to a position I depending on whether the new glass sheet is thicker or thinner. On the left-hand side in fig. 1 there is shown a thinner glass sheet 4 which is carried on a table 5 lying on the same level as the right-hand side table. The question can be about a common stationary table 5 for effecting the grinding of the 2,0 mm and 2,5 mm thick glass sheets included in a pair of glass sheets on an automatic line alternately in successive stages I and II. At each stage I and II the grindstone 1 is placed on a level for bringing its grinding groove 2 symmetrically into contact with the side edges of glass sheet 3 or 4. The necessary shifting distance for a glass sheet is half of the difference in glass sheet thickness, e.g. in this case 0,25 mm.
[0007] In fig. 2, the same components are indicated by the same reference numerals as in fig. 1. The apparatus of fig. 2 differs from fig. 1 in that grindstone 1 is provided with two grinding grooves 2' which are U-shaped. The narrower groove 2' can be used for form grinding the edge of thinner glass sheets 4 and the wider groove 2' is used for form grinding the edge of a thicker glass sheet 3. Thus, the shape and number of grinding grooves in grindstone 1 can vary.
[0008] The shifting of grindstone 1 in vertical direction is effected by only shifting grindstone 1 and its driving shaft 7, as explained in more detail hereinafter with reference to figs. 3 and 4. Grindstone 1 is secured to the bottom end of driving shaft 7. Drive shat 7 is journalled to a body 6 through the intermediary of a tubular axle 8 by means of bearings 9. The relative rotating motion of drive shaft 7 and tubular axle 8 is transmitted by means of torque rods 10 which permit the axial movement of drive shaft 7 and its associated grindstone 1 relative to tubular axle 8. The top end of drive shaft 7 is fitted with a belt pulley 11 rotated by a drive motor (not shown) through the intermediary of a belt 12.
[0009] The top end of drive shaft 7 is engaged through the intermediary of a rotary joint 13 by a piston rod 15 extending through a pneumatic cylinder 14. Pneumatic cylinder 14 is fitted in a bowl-shaped portion 16 which is fastened to body 6 by means of its external thread 17. The bottom of bowl-shaped portion is provided with a set screw 18 which limits the upward movement of the piston of cylinder 14 by hitting the top end of piston rod 15.
[0010] For example, when grinding 2,0 mm and 2,5 mm glass according to stages I and II in fig. 1, the operation of adjusting means proceeds as follows:
1) for 2,0 mm glass the position I of grindstone 1 is adjusted with thread 17 (lower position adjustment)
2) for 2,5 mm glass the position II of grindstone 1 is adjusted with screw 18 (upper position adjustment)
3) pneumatic cylinder 14 is used to shift grindstone 1 from position I to position II. In position I the piston cylinder 14 responds to the cylinder base and in position II piston rod 15 responds to screw 18.
[0011] It can be appreciated from the above that the upper and lower position of a grindstone can be adjusted at high percision and, after completing the adjustment, the grindstone can be shifted rapidly and automatically between positions I and II. For example, the vertical adjustment of grindstone 1 provided with a single groove 2, 2' can correspond to a setting range from 1,5 mm glass thickness to 6 mm thickness, in which case the adjustment distance of a grindstone is 2,25 mm. Such a small adjustment distance can be readily achieved with the solution shown in fig. 3. A corresponding structural design, with slightly modified dimensions, can also be used for fulfilling the adjustment requirement shown in fig. 2.
1. An apparatus for grinding the edge of a glass sheet, said apparatus comprising a substantially
horizontal glass sheet carrying table (5), a rotatable drive shaft (7), a grindstone
(1) attached to drive shaft (7) and having its periphery formed with one or more V-
or U-shaped grooves (2, 2'), the grindstone being adapted for vertical movement relative
to the plane of carrying table (5), characterized in that said drive shaft (7) is enveloped by a tubular axle (8) rotating therealong
and rotatably journalled (9) to a body (6), said drive shaft (7) being axially movable
inside the axle, and that the end of drive shaft (7) opposite to grindstone (1) is
engaged through the intermediary of a rotary joint (13) by adjusting means (14-18)
for adjusting the axial position of drive shaft (7) relative to body (6).
2. An apparatus for grinding the edge of a glass sheet, said apparatus comprising a substantially
horizontal glass sheet carrying table (5), a rotatable drive shaft (7), a grindstone
(1) attached to drive shaft (7) and having its periphery formed with one or more V-
or U-shaped grooves (2, 2'), the grindstone being adapted for vertical movement relative
to the plane of carrying table (5), characterized in that said drive shaft (7) journalled for axial movement relative to a body (6)
is engaged through the intermediary of a rotary joint (13) by adjusting means (14-18)
for adjusting the axial position of drive shaft (7) relative to body (6) and that
said drive shaft (7) is further connected by means of power transmission units (11,
12) to a positionally stationary driving motor.
3. An apparatus as set forth in claim 1 or 2, characterized in that said adjusting means include a power cylinder (14) fitted in a bowl-shaped
portion (16) which is axially shiftable to various adjusting positions by means of
a thread (17).
4. An apparatus as set forth in claim 3, characterized in that the bottom of bowl-shaped portion (16) is fitted with a set screw (18) to
which a piston rod (15) extending through power cylinder (14) responds when the piston
of cylinder (14) is shifted in the direction corresponding to the adjusted position
of a grindstone for a thicker glass sheet (3).
5. An apparatus as set forth in claim 3 or 4, characterized in that the piston of power cylinder (14) limits the shifting movement of drive shaft
(7) in the direction corresponding to the adjusted position of grindstone (1) for
thinner glass sheets (4), said adjusted position being settable by means of a thread
(17) on said bowl-shaped portion (16).