Rattaro, Camillo (Viale Villa Chiesa 40 a/3, Genova, I-16155, IT)
Rattaro, Camillo (Viale Villa Chiesa 40 a/3, Genova, I-16155, IT)
| 1. | Device for supporting workpieces during machining, and in particular to support spectacle lenses, comprising a supporting member (13,1) on which are arranged two clamp means (2) each designed to grip in the middle a portion of a lens (30), means (12,11) being provided for moving the said supporting member (13,1) on a horizontal plane relative to a fixed tool (20,22), which device is characterized in that there are defined for each clamp means (2) a first axis more or less parallel to the midplane in which the gripped portion of the lens (30) lies, and perpendicular to the clamping direction of the said clamp means (2), and a second axis perpendicular to the said first axis lying in the same plane, each of the said clamp means (2) being able to be rotated about the said first and second axes by means of suitable rotary drive means (201,211, 221,301, 303, 403), and the said first axes of the two clamp means (2) being parallel to each other. |
| 2. | Device according to Claim 1, characterized in that the said clamp means (2) are able to be rotated about their respective first axes through equal angles in opposite directions, rotary drive means (211,221, 301) being provided for rotating the said clamp means (2) in a strictly mutually correlated manner. |
| 3. | Device according to Claim 1, in which the said supporting member comprises a plate (13) on which there is positioned a hollow body (1) provided with at least one wall (501) perpendicular to the plane of the said plate (13), the said clamp means (2) being connected to and projecting from the said wall (501) of the said hollow body. |
| 4. | Device according to Claim 3, in which the said clamp means (2) are connected to hubs (101) projecting from the said wall (501) and attached to rotary drive means (211,221, 301) located inside the said hollow body (1). |
| 5. | Device according to Claim 4, in which the said rotary drive means comprise two coaxial gearwheels (301) integral with the said hubs (101), each engaging with the respective threaded portion (221) of a shaft (211) running at right angles to their axes. |
| 6. | Device according to Claim 5, in which the said shaft (211) can be turned from the outside relative to the said hollow body by means of two fingerwheels (201) mounted on its two ends and projecting from the side walls (601) of the said hollow body. |
| 7. | Device according to Claims 4, in which the said clamp means (2) each comprise articulatedjaw means (102,702, 202), each of the two elements (102,702, 202) of the said jaw means being provided, at the furthest end from the said articulation (602,142) with pad means (103,203) that are designed to accommodate the said lens (30) and that are connected in a pivoting manner to their respective element (102,202). |
| 8. | Device according to Claim 7, in which at least one of the said pad means (203) is provided with rotary drive means (303, 403)'for rotation about an axis perpendicular to the axis of the said hub (101). |
| 9. | Device according to Claim 8, in which the said rotary drive means comprise a rod (303) projecting radially from the said pad (203) and inserted in a sliding manner into a tube (403) containing elastic return means (323) and having at its free end a pin (413) capable of engaging with a plurality of cavities (302) formed in a portion (702) of the respective element (202,702) of the said jaw means. |
A support for machining spectacle lenses must guarantee the best possible control of the area to be machined, the best working accuracy and the least possible risk of damage to the object being machined. In recent years, with the introduction of new types of spectacles with minimal frames, the problem of how the lenses are to be machined, and how they are to be supported during this process, has become much more acute than in the past.
European patent application EP-A-0 739 683 in the name of the present applicant disclosed a support for machining spectacle lenses comprising a base on which are arranged two clamp means each capable of gripping one portion of a lens.
Each clamp means defines an axis that is more or less perpendicular to the portion of lens being gripped. Each clamp means is positionable and lockable with this axis oriented in any direction within an imaginary cone having a vertex through which this axis passes. Positioning means are provided for moving the said base along a horizontal plane with respect to a fixed tool.
An apparatus of this type permits a wide spectrum of adjustments to the positions of the lenses with respect to the tool that is to work on the lenses, but it is felt that access to the edges of the lenses is quite limited. In addition, the position of each lens has to be adjusted individually, and because of the typical ratios of mirror symmetry found in the lenses of the same pair of spectacles, this aspect considerably complicates the use of the supporting device.
It is therefore an object of the present invention to provide a supporting device, particularly for spectacle lenses, that will enable the workpiece to be machined with greater freedom of approach by the tool, and that will enable the two lenses of one pair of spectacles to be positioned in such a way as to maintain their typical symmetry.
The subject of the present invention is therefore a device for supporting workpieces during machining, and in particular to support spectacle lenses, comprising a supporting member on which are arranged two clamp means each designed to grip in the middle a portion of a lens, means being provided for moving the said supporting member on a horizontal plane relative to a fixed tool ; there are defined for each clamp means a first axis more or less parallel to the mid-plane in which the gripped portion of the lens lies, and perpendicular to the clamping direction of the said clamp means, and a second axis perpendicular to the said first axis lying in the same plane, each of the said clamp means being able to be rotated about the said first and second axes by means of suitable rotary drive means, and the said first axes of the two clamp means being parallel to each other.
In a preferred embodiment, the said clamp means are able to be rotated about their respective first axes through equal angles in opposite directions, rotary drive means being provided for rotating the said clamp means in a strictly mutually correlated manner.
Other advantages and features of the device according to the present invention will become clear in the course of the following detailed description of one embodiment. This is provided by way of non-restrictive example with reference to the attached sheets of drawings, in which: Figure 1 is a perspective view of an apparatus for machining lenses using the device according to the present invention; Figure 2 is a perspective view of an enlarged detail of Figure 1, with the clamp means rotated to a different position from the latter figure ; Figure 3 is a similar view to Figure 2, except for the fact that the clamp means have no lenses and that the view here includes a partial cutaway; and Figure 4 is a side elevation view with parts in section of a detail of Figure 1.
Figure 1 illustrates an apparatus for machining spectacle lenses using the device according to the present invention. Reference 10 denotes a base on which there stands, via two uprights 21, the tool 20 equipped with the working head 22. On the base 10 in the portion beneath the working head 22, is a guide 11 on which a slide 12 travels. The plate 13 on top of the slide 12 can be moved relative to the said slide in a direction perpendicular to that of the guide 11, by drive means operated through the fingerwheel 14, and not examined in greater detail here. Mounted on the edge of the plate 13 nearest the uprights 21 of the tool 20 is the hollow body 1, from whose wall 501 overlooking the plate 13 there project two rotatable hubs 101, to which the clamp means 2 are attached via a connection to the plate 702 of these means. The said clamp means 2 comprise a rocker 102 which pivots in the fork 602 made at one end of the said plate 702. This rocker 102 has a pad 103 at one end to clamp the lens 30, and at the other end is connected to the adjustment screw 502.
The pad 203, which grips the lens 30 from the other side from the pad 103, is mounted so as to be able to tilt on the arms 202 projecting from the plate 702. The two fingerwheels 201 project out from the sidewalls 601 of the body 1.
Figure 2 shows an enlarged detail of the apparatus of Figure 1, specifically the body 1 from which the clamp means 2 of the device according to the present invention project. The same numerals are used for the same parts. The figure shows greater detail of the clamp means 2; the plate 702 of each of the said clamp means 2 is attached to the hub 101 projecting from the body 1 by the screws 402; and each hub 101 has a radially projecting pointer 111 whose movements can be gauged against a graduated scale 121 formed on the wall 501 of the body 1. The pad 203 is able to pivot with respect to the clamp means 2 to allow the spindles 213 to be inserted into the recesses 212 in the arms 202. The pad 203 is also fitted with a radial rod 303 which engages with a cube 403. The latter has a radially projecting tab 423, while its free end ends in a pin 413 which fits into one of the cavities 302 formed in the plate 702. The other pad 103 is connected to the fork 122 of the yoke 112 fitted to the outward end of the rocker 102. The other end of this rocker 102 is hinged to the fork 602 of the plate 702 of the clamp means, and it is at this end that the adjustment screw 502 is mounted on the said rocker. It should be observed that the two clamp means 2 are both rotated through 90° compared with their position shown in Figure 1, and in mutually opposite directions. The heads of the two adjustment screws 502 of the rockers 102 do not interfere with each other.
Figure 3 shows the inside of the body 1: fingerwheels 201 are keyed to a shaft 211 on which the two threaded portions 221 are mounted and mesh with the gearwheels 301, the latter in turn keyed to the spindles 131 coaxially with the hubs 101. The shaft 211 runs through the holes 401 in the sidewalls 601 of the hollow body 1.
Figure 4 is a side elevation view with parts in section showing more clearly how the clamp means 2 clamp the lenses 30. A tapped through hole 132 is formed in that portion of the rocker 102 which is nearest the wall 501 of the body 1, and takes the adjustment screw 502. The free end of the shank of the screw 502 ends in an unthreaded tail 522, which sits in the cavity 141 formed radially in the said hub 101.
Around the outside of the said tail 522 is a helical spring 542 which presses against a washer 512 held against the bottom end of the threaded portion of the screw 502.
The rocker 102 is hinged to the plate 702 by the spindles 142 which engage with the fork 602.
Turning now to the manner in which the position of the pad 203 is adjusted, it can be seen that the radial rod 303 projecting from the said pad 203 is fitted at its free end with a plunger 313 which, inside the cylindrical chamber 433 formed in the tube 403, compresses a spring 323. The compression of the spring 323 forces the pin 413 on the end of the tube 403 into one of the cavities 302 formed in the plate 702.
The operation of the device according to the present invention will be obvious from the following account. The lens 30 clamp means 2 permit, in an apparatus of the type illustrated in Figure 1, a wide spectrum of possible adjustments of position relative to the working head 22 of the tool 20. No such opportunity existed with the known devices of the prior art. Specifically, as can be seen in Figure 2, the lenses can be rotated through any angle relative to the axis of rotation of each hub 101. This makes it easy to work even on the lateral surfaces of the lenses, which are always securely supported. Also, the particular rotary drive of the hubs 101, that is the threaded portions 221 on the shaft 211, make for extremely accurate control of the angles of inclination, which can easily be read by means of the pointers 111 and the graduated scales 121.
Another important feature is the fact that, as is clear from Figure 3, a rotation of the shaft 211 effected by turning one of the fingerwheels 201 causes both hubs 101 to rotate through an equal angle in mutually opposite directions. This system guarantees a mirror symmetry of the positions of the two lenses 30 in their respective supports. This symmetry is essential for correct machining of the lenses, which are intended to form the same pair of spectacles.
As described earlier, the pads 103,203 which grip the lens 30 can also pivot: the inclination of the pad 203 is adjusted by appropriately positioning the pin 413 of the tube 403, i. e. pulling on the tab 423 of the said tube to withdraw the pin 413 from the cavity 302 in which it is positioned, and moving the pin into the cavity 302 corresponding to the desired tilt. The spring compressed inside the chamber 433 of the tube 403 ensures that the position of the pad 203 remains stable. Clearly, means could be provided to allow a continuous variation of this angle of tilt, but the angles obtainable in this way can be regarded as satisfactory. The pad 103 will adjust itself to the position imposed on the pad 203, since the pad 103 is able to pivot freely relative to the fork 122 of the yoke 112.
The way the lens 30 is gripped in the clamp means 2 can be deduced from the illustration of Figure 4: when the adjustment screw 502 is made completely slack, the spring 542 exerts a certain force on the rocker 102 portion nearest the wall of the body 1. In this situation the lens 30 can be positioned between the pads, without the risk of its slipping out, as the spring produces a certain load on the pad 103. Once the lens 30 has been inserted, the tilt of the pads 103,203 can be adjusted in the manner described above. As the screw 502 is tightened, the pad 103 is pushed towards the lens 30 until the lens is perfectly secure. At this point the two clamp means 2 can be rotated as required relative to the axes of the respective hubs 101 by turning the fingerwheels 201 until the lenses are in the desired position for machining.