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(11) | EP 0 197 233 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A machine for working circular profile edges of slabs of marble, granite, and the like |
| (57) 57 A machine for working at least part-circular profile edges of slabs of marble,
granite, and the like, the machine comprising a flat conveyor belt (3) for supporting
a slab, two uprights (6, 7) located close to the opposed ends of the conveyor surface,
and a tool holding device (35) carried on the uprights (6, 7). Said device (35) includes two double articulated parallelograms (13, 24) (DAP), identical to and confronting each other, which are carried on respective ones of the uprights (6, 7), each DAP (13,24) having a fixed side extending across the respective upright perpendicularly to the conveyor belt, two crank levers (14, 16) whose pivot pins (15, 17) are supported on a respective one of the uprights, and two connecting rods (18, 19) interlinking the two crank levers (14, 16); the device further includes a tool holding table (35), extending between the two DAP's (13, 24) and having its opposed ends journalled to the connecting rods (18, 19), a plurality of power-driven tools (47) received on the table and facing the conveyor belt, and means (50) of shifting the crank levers (14, 16) about their respective pivot pins. Thus, the tools (47) can be shifted angularly around the slab edge to enable the working of circular profile edges thereon. |
BACKGROUND OF THE INVENTION
[0001] This invention relates to a machine for working circular profile edges of slabs of marble, granite, and the like, which comprises a flat conveyor belt for supporting a slab, two uprights positioned close to the opposed ends of the conveyor surface, and a tool holding device carried on said uprights.
[0002] Machines for working, in particular polishing, edges of marble, granite, and the like slabs automatically have long been available. Such prior machines can polish straight edges, or at most, flat inclined edges. Where, by contrast, an edge of a slab having a circular profile is to be polished, manual polishing must be resorted to. This adversely affects processing costs; in fact, not only is the time required for the operation lengthened, but highly skilled labor must be available.
SUMMARY OF THE INVENTION
[0003] Accordingly, it is an object of this invention to provide a machine for working circular profile edges of slabs of marble, granite, and the like, which enables automatic working, specifically polishing, of the edges even where these have circular profile shapes.
[0004] This object is achieved, according to the invention, by a machine as indicated, characterized in that the tool holding device comprises:
two double articulated parallelograms, identical to and confronting each- other, being carried on respective ones of said uprights, each double articulated parallelogram including a fixed side extending across a respective one of said uprights perpendicularly to said conveyor belt, two crank levers whose pivot pins are supported on the respeet- ive one of said uprights, and two connecting rods interlinking said two crank levers;
a tool holding table extending between said two double articulated parallelograms and having its opposed ends journalled to said connecting rods;
a plurality of power-driven tools received on said tool holding table and facing said conveyor belt; and
means of shifting said crank levers angularly about their respective pivot pins.
[0005] Thus, the tools may be displaced around the edge of a slab (by just moving the crank levers of the double articulated parallelograms) to permit working of circular profile edges.
[0006] According to another peculiar aspect, a machine according to the invention also comprises a means of adjustably moving the tools to and away from the conveyor belt surface to accommodate different thickness slabs.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Further features and advantages of a machine according to the invention will become apparent from the following description of a preferred embodiment thereof, in conjunction with the accompanying drawings, where:
Figure 1 is a partly sectional perspective view of a machine according to the invention;
Figure 2 is a perspective view showing diagrammatically some details of the linkages in the machine of Figure 1;
Figure 3 is a sectional view showing the machine of Figure 1 at work on a slab;
Figures 4 and 5 are diagrammatic perspective views showing a detail of the linkages in the machine of Figure 1, at two different stages of a slab working; and
Figures 6 and 7 show respectively diagrammatic perspective views of a detail of the linkages in the machine of Figure 1, at two different stages of a slab working.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0008] With reference to the drawing figures, generally indicated at 1 is a machine for working, specifically polishing, edges on slabs of marble, granite, and the like. The machine 1 comprises a bed 2 which provides support for a flat conveyor belt 3; the belt 3 is set substantially horizontally and carries and moves the slab 4 being worked. For convenience in the operations two lead-in rolls 5 are provided.
[0009] The machine 1 also comprises two vertical uprights 6 and 7 of box construction, placed on one side of the belt 3 close to the opposed ends thereof.
[0010] Associated with the upright 6 are an upper plate 8 and a lower plate 9.,With reference to Figures 6,7, each of said plates, 8,9, has a substantially rectangular shape, and is supported in a vertical position within a respective one of the uprights 6,7, it being adjustably positioned along said upright (6,7) between an upper position and a lower position. More specifically, each plate 8,9 is supported slidably on two straight guides 11 set at 45° off the vertical. The upright 6 also includes means of locking the plates 8 and 9, such as bolts, all indicated at 10.
[0011] The upright 6 supports, through the two plates 8 and 9, a double articulated parallelogram, generally indicated at 13, hereinafter referred to as DAP for brevity. More particularly, the DAP 13 comprises an upper crank lever 14 mounted pivotally on a pivot pin 15, carried on the upper plate 8, and a lower crank lever 16 mounted pivotally on a pivot pin 17, carried on the lower plate 9. Said pivot pins 15,17 define the fixed side 12 of the DAP 13 which extends across the upright 6 perpendicularly to the plane of the conveyor belt 3. The crank levers 14 and 16 are interlinked by two parallel connecting rods 18 and 19, associated with the crank levers 14 and 16 by pins 20,21 and 22,23, respectively.
[0012] Symmetrically likewise, the upright 7 supports two plates (not shown in the drawings) being mirror- images of the plates 8 and 9, whereon a DAP 24 is mounted which is identical to and confronts the DAP 13; the DAP 24 comprises, like the DAP 13, an upper crank lever 25 journalled to a pivot pin 26 which is carried on the upper plate (not shown), a lower crank lever 27 journalled to a pivot pin 28 carried on the lower plate (not shown), and two parallel connecting rods 29 and 30; the connecting rods 29 and 30 are respectively associated with the crank lever 25 through pins 31 and 32, and with the crank lever 27 through pins 33 and 34.
[0013] The two DAP's 13 and 24 support a tool holding table 35. In particular, the table 35 is provided with four pins 36,37,38,39, in opposed and aligned pairs (36 with 38, 37 with 39); by means of said pins 36,37,38,39, the table 35 can be associated with the crank levers 14,16,25,27.
[0014] Thus, the table is guided by the two DAP's 13 and 24, and is, therefore, movable angularly about an axis of rotation 44 extending parallel to the axes of the crank pins 15,17,26,28.
[0015] The table 35 supports a plurality of power-driven tools 45; more specifically, each tool 45 comprises an electric motor 46, a cup grinding wheel 47, and a device for shifting the grinding wheel along its rotation axis; this device is of conventional design and is only_schematically illustrated in the drawings at 48.
[0016] The machine 1 further comprises means of shifting angularly the crank levers (and hence, the table 35 with the tools 45) about their respective pins. Such means comprise, for each DAP, a sprocket wheel 49 attached to the crank lever 14 and mounted coaxially pivotally on the pin 1,5. The wheel 49 is kinematically connected to a drive unit, such as a cylinder-piston unit 50 which drives a rack 51 in engagement with a pinion gear 52; the pinion 52 is coaxially fast with a sprocket wheel 53, connected to the wheel 49 by a chain 54, for rotation therewith. The drawing figures only show details of the DAP 13, those relating to the DAP 24 being quite identical.
[0017] It should be noted that the table 35 with the tools 45, the two DAP's 13,24, the plates 8,9 for supporting and adjustably positioning the crank pins 15,17,26,28 on said DAP's, and the means (49,50,51, 52,53,54) of shifting the crank levers angularly about their respective pivot pins, form jointly a tool holding device.
[0018] The machine 1 also includes a counterweighing device resisting the rotation of the crank levers under the weight of the tool holding table 35. More specifically, that device comprises, for each of the two DAP's 13,24, a flexible cable 56 attached with one end to the upper crank lever 14,25 of the DAP, and with the other end to a counterweight 57 located at the end of an arm 58 attached pivotally to its respective upright 6,7. Each cable 56 is guided on six pulleys 59,60,61,62,63,64.
[0020] A slab 4 to be polished, having a circular profile edge 4a, is laid onto the conveyor belt 3 and entrained thereby in a position with the axis of the edge 4a coincident with the axis 44.
[0021] During this movement, the edge to be polished contacts in succession all of the grinding wheels 47, as with conventional machines. Differently from the latter, however, wherein the grinding wheels are mounted stationary and can only grind a flat edge, the tool holding table 35 of this machine 1 is constantly moved angularly about the axis 44, to repeatedly move back and forth over an arc of 180°.
[0022] In fact, the cylinder-piston unit 50 is driven constantly in both directions; the motion of the piston is thus transferred (via the rack 51, pinion 52, sprocket 53, chain 54, and sprocket 49) to the crank levers of the DAP's which will keep moving angularly back and forth about their respective pivot pins. Similarly to the crank levers, the table 35 will be moved back and forth about the axis 44.
[0023] The grinding wheels 47 on the table 35 will, therefore, follow the-surface of the circular profile edge 4a.
[0024] For adjusting the machine to polish slabs having different radii of curvature and/or different thickness dimensions, it will be sufficient to manipulate the two adjustment features of the machine.
[0025] Thus, as an example, for a different radius of curvature, the grinding wheels 47 should be shifted axially on the table 35 by means of the devices 48. In order to shift the center of curvature, it will be sufficient to displace the DAP's 13 and 24 relatively to the uprights 6 and 7; to this end, all of the bolts 10 would be loosened and the plates 8 and 9 slid along their respective guides 11 and 12, as far as a desired location. The 45° inclination of the guides provides for high locating accuracy.
[0026] It should be noted that the machine 1 can also work flat edges, in the same way as traditional machines; in fact, it would be sufficient to stop the cylinder-piston unit 50 and lock the grinding wheels 47 in a position providing a sought inclination on the slab.
[0027] Of course, it is also possible to work on the machine 1 edges of complex configurations, wherein the edge profile results from various combinations of straight and circular portions. It will be sufficient to work such portions separately, one after another, using appropriately selected machine settings.
two double articulated parallelograms (13,24), identical to and confronting each other, being carried on respective ones of said uprights (6,7), each double articulated parallelogram (13,24) including a fixed side extending across a respective one of said uprights (6,7) perpendicularly to said conveyor belt (3), two crank levers (14,16,25,27) whose pivot pins (15,17,26,28) are supported on the respective one of said uprights (6,7), and two connecting rods (18,19,29,30) interlinking said two crank levers (14,16, 25,27);
a tool holding table (35) extending between said two double articulated parallelograms (13,24) and having its opposed ends journalled to said connecting rods (18,19,29,30);
a plurality of power-driven tools (45) received on said tool holding table (35) arid facing said conveyor belt (3); and
means (49-54) of shifting said crank levers (14,16,25,27) angularly about their respective pivot pins (15,17,26,28).
a sprocket wheel (49) attached to one crank lever (14) and fitting coaxially rotatable on the pivot pin 15 of said crank lever (14); and
a drive unit (50) kinematically connected to said psrocket wheel.
a plate (8) pivotally supporting the pin (15) for said crank lever (14) and being carried slidably on the respective one of said uprights (6) by means of at least one prismatic guide (11) inclined at 45° on the fixed side of the double articulated parallelogram (13); and
means (10) of removably securing said plate to the respective one of said uprights.