MXPA96003307A - Process and tool for the production of a concave surface from an eyeglass crystal piece - Google Patents

Abstract

The present invention discloses a process for the manufacture of a surface from an eyeglass lenspiece, which is suitable for both hardened material and plastic material. A symmetric rotatably discoidal-shaped tool is used which comprises a relatively large diameter, and with which at least in two working steps- an insertion-mechanization step and a molding step using material extracted along a spiral-shaped course- the material is extracted from the working piece with a high rectification and milling yield. A spiral-shaped line results from the latter working step which runs inwardly from the outside with a reduced residual tip height and a tip separation relatively large. The surface so manufactured requires only a reduced rectification and polishing process. In an alternate embodiment of the present invention, an edge mechanization process can be included in the process for adjustment of the lenses frame shape as well as a process for the formation of a facet in the eyeglass lenses edge. The tools for performing the rectification and milling processes are further disclosed.

Description

PROCEDURE AND TOOL FOR THE PRODUCTION OF A CONCRETE SURFACE FROM A GLASS PIECE OF ANTEOJOS DESCRIPTION OF THE INVENTION The present invention relates to a method for the production of a concave surface from a piece of spectacle glass, in accordance with the general concept of claim 1, and also includes tools for the execution of the procedure in glass parts for hardened eyeglasses and plastic. In a known process of the kind referred to in the introduction (DE 42 10 381 A1), the tool and the work piece are controlled during the entire course of the process, so that the extraction of material takes place exclusively along the length of the process. a spiral shaped course. In this way, it is possible to mold the concave surface corresponding to the surface of the end lens, however, this is achieved with a reduced machining efficiency. In the event that greater extractions of material with the tool are to be carried out in this way, both the workpiece and the tool must move several times along the course terminally to each other, which in the completion of Glass recipes for glasses leads to undesirable long processing times.

The object of the present invention is to propose a method of the kind proposed in the general concept of claim 1, with which a greater machining performance can be achieved both with hardened materials as well as with plastic materials for the manufacture of surface forms common concaves in the optics of the glasses of glasses with the result of a uniform surface quality and shorter processing times in a precise and economical way. The object of the present invention also comprises the preparation of suitable tools for the execution of the process. The object presented is achieved through the features of claim 1. Advantageous additional configurations of the method are presented in claims 2 to 5, as well as a clarification in greater detail. The special tools for carrying out the process are indicated in claims 6 and 7 of which claim 6 contains the tool configuration for hardened materials and claim 7 the tool configuration for plastic materials. The stepwise division of the process of the present invention into two stages of work, that is, into an insertion-processing stage and a second stage of work with the extraction of the material along a spiral-shaped course, causes processing times , extremely reduced. In the insertion-processing stage, high machining yields and, where appropriate, grinding are possible, so that the main portion of the material of the workpiece is quickly extracted. The continuous step of insertion or insertion-processing saves the many necessary cuts of the known methods in the case of glass pieces for thicker glasses. From the insertion-processing stage, at least in the area of the outer margin, a surface corresponding to the external contour of the internal surface of the optically effective glasses glass is achieved. The method of the present invention enables the manufacture of surfaces with greater accuracy. With its help, several common surface forms can be manufactured in the spectacle optics industry, that is, toric, prismatic, off-center, multifocal or atoric in glass and plastic. Preferably, a process of marginal processing has been integrated into the method according to the present invention and according to claim 2, with which it is possible to manufacture, not only glasses of comfortable thin glasses, but also for the subsequent adaptation of the crystals in the frame and also achieved a reduced working time with less wear of the tool by the eyeglass manufacturer.

For those who use the procedure, the advantage is that a smaller inventory of semi-finished crystals with different diameters is possible. When carrying out the three stages of work, elaboration of the margin, insertion and elaboration along the course in spiral form according to claim 3 in a continuous manner, very short production times are achieved. These work stages can be achieved in a single clamping or blocking of the work piece. When the perimetral edge of the workpiece must be provided with a facet, a stage of facetting work can also be connected according to claim 4 in the course of the procedure, so that with the inclusion of the elaboration process marginal, can be made in total four stages of immediate and successive work with a single subjection or blocking of the work piece. Between both rotational displacement axes c and b, an "angle determined between 90 and 120 ° is possible." Preferably, this angle has been determined according to claim 5, at 105 °, hence with the b-axis of the workpiece ordered vertically, the c axis of the workpiece is placed in relation to the horizontal with an angle of only 15 °, this angle is avoided during the grinding or milling process, also the case of extremely concave spectacle lens surface, a collision between the use of the tool or the tool itself with the glass margin of the telescope The grinding tool that is indicated in claim 6 for carrying out the procedure in a hardened glass spectacle part is extremely advantageous in view of the configuration of the grinding lip, since the cutting geometry remains constant also during grinding, only the diameter of the tool takes at However, it is easy to compensate for the rectification by measuring the thickness of the glass of the rectified telescope and the immediate calculation in the control program. The milling tool according to claim 7 for carrying out the method in a piece of plastic eyeglass lenses is configured in relation to its disc-shaped rotation, with which milling cuts are distributed on the perimeter. The machining performance of this milling tool is high since in the cut a toric envelope surface is defined. It is possible to advantageously increase the dwell time of the milling cut, when the cutting plates of the milling tool are rotatably held in accordance with claim 8. In this way, several fields of the cutting plates can be rotated in one direction. working position, before the cutting plates have to be changed for reasons of wear or that their outside diameter must be rectified. The present invention is explained in more detail in relation to the schematic drawings. There it is shown: Figure 1 is a side view of partial and disintegrated section of a milling and grinding machine for spectacle lenses, Figure 2 is a front view of the machine of Figure 1, Figure 3 is a side view of the grinding tool, Figure 4 is a side view of Figure 3, after using the grinding and wear tool, Figure 5 is a side view of the milling tool, Figure 6 is an amplified feature of the milling tool according to Figure 5, corresponding to the cutting circle VI, Figure 7 is a front view of the milling tool in the direction of arrow VII in Figure 5, Figure 8 of the tool and the workpiece , during the marginal processing procedure,]) two views, ie a side view 'and a previous view of the tool, Figure 9 is a tool and work piece during the work stage of training facets, in two views, in a similar manner to Figure 8, Figure 10 is a tool and work piece during the insertion work stage, in two views, similar to Figures 8 and 9, Figure 11 is a tool and piece of work during the work stage with elaboration along the course in spiral form in two views in a similar way to Figures 8, 9 and 10, Figure 12 is a top view of the tool according to the stage of work with elaboration of the course of terminal form and, Figure 13 is a cut disintegrated and amplified through the tool according to line 13-13 in Figure 12. In the machine of grinding and milling are represented in Figures 1 and 2 to simplify only the supporting, driving and executing parts of the tool 1 and the tool 2. The tool 2 is held along an axis 3 equidistantly, to a use 4, which can be rotated by means of an electric motor 5, where you can c Ontrolar the number of revolutions. The tool 1 is locked on a tool holder 6 which is attached to a use 7 concentrically. The use 7 is operated in a rotary manner and is controlled numerically by a servomotor 8. The work piece 1, the tool holder6, the use 7 the motor 8, as well as all the parts described, attached to these, are placed in a coordinating device of the machine and can therefore be moved together on axes of linear displacement at right angles x and y. The collective central axis of parts 1, 6, 7 and 8 falls with the rotation displacement axis b of workpiece 1. The collective central axis of tool 2, axis 3, use 4 and motor 5 they fall with the rotary displacement axis c of tool 2 and with a tool adjustment axis, z (Figure 1). The linear displacement axes x, y, and the rotation offset axis b are controlled by CNC, while the rotation displacement axis c can only be adjusted in terms of the number of revolutions. The z-axis only serves for the pulse adjustment of the tool 2 on the rotation displacement axis c. Since all CNC axes are linked in the use of the tool, a simpler feed is achieved. The tool can be moved in a defined loading and unloading position, so that manual devices for automatic tool exchange can also be used. In the example described, the angle a determined by the construction of the machine between both axes of rotation b and e has a value of 105 °. The angle is determined in this way by the construction of the machine and can not be changed. The use of the tool 4 with the tool 2 fixed thereto, and with its corresponding electric motor 5, as well as the other joined parts that are not described in such detail, can be adjusted by keeping the angle a, determined by the construction to adjust the tool 2 on the middle of workpiece 1 with a right angle in relation to the axis of displacement x. For this purpose, the aforementioned adjustable parts are connected by means of a load arm 9 with a driving shoe 10 which can be moved in the direction of adjustment provided in a driving bed 11 of the machine. Between the driving skids 10 and the driving bed 11, there is a stringed use 12 which serves for the adjustment, which on the one hand can rotate, but is placed without being able to move in the driving bed 11 and on the other hand inserted in a corresponding rope of the driving shoe 10. For a clarification in more detail of the tool 2 configured as a grinding tool reference is made to Figures 3 and 4. As it follows from this, the grinding tool has its form of disc, with a grinding lip 13 configured in the shape of a ring that is on its perimeter. At the front end of the grinding lip 13 asymmetrically configured, its radius is amplified in relation to use 4, whereby its largest radius runs on a cutting edge with circular shape 14. For the execution of the procedure, this edge must be adjusted. cut on the tool so that it is directed approximately radially with respect to the center of the tool. The back surface 15 of the grinding lip 13 which is located on the cutting edge 14 on the end of the use is configured considering the angle determined by the construction so that the rear surface runs under the angle a in relation to the axis of rotation c of the tool. A vertical through the corresponding deepest point 16 of the cutting edge 14, establishes the rear surface 15 according to the type of a radial sleeve line. The corresponding deepest point 16 is always in the plane of both axes of linear displacement x and y. This is made clearer with a comparison of Figures 3 and 4. The cutting edge 14 is always determined by means of the radius of the grinding lip and is also with the continuous wear of the tool directed approximately radially in relation to the center of the tool. In Figure 4, the new contour of the tool in dotted lines is indicated next to the wear contour. In view of this special geometry of the tool, the cutting edge becomes sharper during the grinding process so that the shape of the work surface is not affected. The reduction caused by the grinding of the radius of the cutting edge can be easily considered in the machine calculation program. The grinding lip material 13 consists of the finely divided diamond portions. Likewise, the grinding lip is formed by sintered material, in which the finely distributed diamond portions are included, or the diamond parts are galvanically joined and held on the grinding lip 13 in an annular manner. For the description of the milling tool 2 'provided for the process with plastic, reference is now made to Figures 5 to 7. As can be seen from Figure 5, the milling tool 2' is configured in the form of a disk in relation to its form of rotation. For this purpose, the milling tool 2 'is provided with a multiplicity of support arms 17, in the example eight uniformly distributed are shown, which project from a central hub portion 18 outwards.

At the outer ends of the support arm 17, cutting plates 19 matching the diameter are fixed. The annular edges 20 of the cutting plates 19 are directed radially in relation to the axis of rotation c of the milling tool 2 'and define a toric envelope surface, which is indicated by dotted lines in Figure 5. The surrounding surface toric, is directed in relation to the plane configured by its largest radius in radial direction towards the center of the tool. Here is the corresponding deepest point 16 of the toric envelope surface always in the plane of both axes of linear displacement x and y. In Figure 6, it is shown that the cutting plates 19 are fastened to the support arms 17 in each case by a central screw 21. With the help of the screw 21, the determined turning position of the cutting plate 19 is fixed on the support arm 17. As indicated in FIG. 6 through the measurement of the angle β, it is used from the perimeter of the annular edge 20 for the milling process only an angle of approximately 90 °, hence only about a quarter of the perimeter of the annular edge is displaced for the milling process. This means that the cutting plates 19 after the first sectors of the cutting edges are worn can be rotated three times to a new position.

To clarify in more detail the course of the procedure, reference is now made to Figures 8 to 11. The development of this procedure comprises all possible work processes, that is, the edge machining procedure (Figure 8), the stage of facet formation work (Figure 9), the insertion work stage (Figure 10) and the machining of the surface in the field of the work stage of the present procedure along the spiral shaped course (Figure 11) ). In the view of the right side of Figures 8, 9, 10 and 11, the relative displacement of the center of the tool against the work piece in dotted lines is indicated. In fact, the tool does not move against the work piece, but vice versa, the work piece moves against the tool. The representation of the development of the method is carried out in the example of a machining of a piece of spectacle glass 1 of a hardened material by means of a grinding tool 2. Mechanization of a leg of plastic spectacle lenses is contemplated. by means of a milling tool. The steps of the edge machining process and facet formation are of free choice in the course of the process, but also preferably simultaneous procedures. Figures 8 to 11 show the sequence of the different steps used in the procedure. The axes x, y, b and c which are indicated only symbolically in Figure 8 are valid for all Figures 8 to 10. The locked workpiece 1 is then approached through a lateral placement on the x axis towards the tool 2 , where the workpiece 1 is placed on the shaft and against the tool 2 which remains fixed in place, until the workpiece 1 is approximately at an equal height with the tool axis and the edge of the tool. the work piece establishes a tangent with the cutting edge 14 of circular shape. Here the rotation of the tool and workpiece is carried out around the corresponding rotation displacement axes c or b to extract the material from the edge of the workpiece. Through the additional lateral movement of the workpiece 1 on the x-axis and continuous positioning on the axis, the machining of the lens part for the spectacle lens is now carried out through the contour of the perimeter indicated for it. By placing the work piece 1 on the shaft and taking the tool on the edge of the workpiece takes place approximately according to a spiral line. After terminal the contour of the perimeter, the process of facet formation of the edge of the perimeter of the work piece is performed by means of the tool.

Beta et pa of work is carried out in continuous succession with the other work stages under a constant rotation of the work piece and the tool. With this, the loss and direction of the formation of the desired facet of the workpiece 1 and of the tool 2 on the x axis is correspondingly approximated and the workpiece is also displaced with a displacement superimposed on the axis and down until the surface 22 of the desired facet is achieved. With a sequence of the continuous and additional process steps, the workpiece 1 against the tool 2 in the insertion stage is placed under constant rotation of the workpiece and the tool around the corresponding axes of rotation. -Mechanization through a coordinated movement, controlled by the program on the x and y axes, until the tool and the work piece are placed approximately in the relative position shown in Figure 10. At this point in the course of the procedure, The main quantity of material is extracted from the work piece. With this, a surface 23 with a discoidal shape is achieved as far as possible of the surface that must be produced. In addition, an outer margin 24 is achieved, which corresponds to the outer contour of the interior lens surface of the glasses optically effective. This concludes the insertion-mechanization stage. In addition, the last work step is carried out, which is clarified in Figure 11 with a continuous sequence, which is used to extract the residue of the material from the excess work piece, until the final shape of the surface is achieved. Here, a displacement is superimposed between the workpiece 1 which rotates around its axis b and the tool 2 fixed in place around its axis c in the direction of the x-axis and the y-axis with a spiral-shaped course of the machining pattern indicated in Figure 12 on the machining surface. In this last stage of work, the discoidal surface disappears that emerges from the insertion-mechanization stage, in fact the central tip of approximately conical shape of this surface. Due to the large diameter of the cutting edge 14 for shaping the tool 2, a very small groove is formed in the spiral machining line, in fact a very poor groove of the tip on the base of the slot. This implies, for example, with a diameter of the cutting edge 14 of 70 mm only 0.0642 mm, with a tip spacing of 5 mm. These relationships are represented in Figure 13. In addition, it results after the last stage of the procedure, in fact from the work stage with machining along the spiral pattern, a work surface, which has an exact previous shape so that the fine grinding and the polishing work are extremely reduced. For simplicity, the fabrication of a spherical-concave surface is shown and shown. Obviously, other surface shapes than those previously mentioned can also be manufactured by means of a corresponding program control of the x and y axes. A method for manufacturing a surface of eyeglass lens parts is described, which is suitable for hardened materials as well as plastic materials. For this, a tool with a symmetrical rotating disk with a large diameter is used, with the help of which, in at least two stages of work, an insertion-mechanization step and a molding step with inspection of the material Along a spiral-shaped course, material is extracted from the workpiece with high grinding or milling performance. Here, a spiral-shaped machining line running from the outside inwards with a reduced residual tip height with a relatively large tip gap results from the last work step. The surface produced requires only a fine grinding and a reduced grinding process. Optionally, a process of edge machining can be integrated into the process to adapt it to the frame as well as a process of forming facets of the edge of the lens of the glasses. In addition, tools for the execution of the rectification and milling procedures are proposed.

Claims (8)

1. CLAIMS 1. A method for manufacturing a concave surface of a workpiece for eyeglass lenses (workpiece), which additionally corresponds to the inner surface of the eyeglass lens, by means of a milling or grinding tool , in which the locked workpiece and the tool move in a CNC control machining procedure with two linear displacement axes (x and y axes) and two axes 10 rotation movement under an angle (a) to which the workpiece (axis b) and the tool (axis c), with a relative approach movement, are sorted, with which the material is removed as required. length of a course of spiral form on the surface, and in which the The tool and the workpiece are moved by controlling them relative to each other in relation to the x, y, and b axes, a symmetric rotating discoidal tool is used as tool, which is configured in such a way that the deepest point (16, 16 ' ) of the tool is 20 in a plane defined by the axes dyx, characterized in that the extraction of material along the spiral-shaped course is connected to an insertion-machining work step, in which the workpiece rotates about the axis (b) and the tool moves at least in The direction of the axis and until a disc-shaped surface of the work piece is achieved in the field of the outer edge of the concave surface to be manufactured, so that at least in the field of the outer edge of the surface produced in the workpiece, the outer contour of the regimen corresponds to the inner surface of the optically effective telescope lens. The method according to claim 1, characterized in that before the step of inserting-machining the edge of the lens of the telescope to adapt it to the frame contour of the glasses, this is machined in a process without working of the edge, where the tool and the work piece are first approximated by a relative lateral displacement on the x axis between them, with which the tool and the work piece are placed through a relative displacement on the y-axis, until the The workpiece is located approximately at the same height as the tool axis and the edge of the workpiece touches the circular cutting edge of the tool, so that with the rotation of the tool and the workpiece around it of the corresponding rotation displacement axes (axes c and b) the material is extracted from the edge of the workpiece, thereby through a relatively lateral displacement on e the x-axis and a continuous feed on the y-axis, and a machining of the lens part of the goggles is performed on the contour of the perimeter provided by the shape of the frame of the goggles. 3. The method according to claim 1 or 2, characterized in that, in a single workpiece clamping, the step of machining the edge, the insertion-machining step and the process along a spiral shaped course continuously and sequentially. The method according to claims 1 to 3, characterized in that, before the insertion-machining step and, where applicable, after the machining process of the edge, the facet of the edge of the perimeter of the work piece is formed by means of of a tool, where the mechanization cover of the facet is carried out in a continuous sequence with the other stages of work. The method according to claims 1 to 4, characterized in that, the angle (a) between the axis of the workpiece (b) and the tool axis (c) during the entire work process is 105 °. 6. A disk-shaped grinding tool with an annular grinding lip for carrying out the method according to claims 1 to 5 for the production of a concave surface from a workpiece for the lenses of the glasses hardened, characterized in that, the grinding lip is configured asymmetrically on the tool and with its greater radius runs projecting on a cutting edge, which provides a circular shape, and because the grinding lip, is displaced, runs on the rear surface of the wall 15 of the mouth of the cut edge of the tool towards the axis of rotation of the tool (c) under the angle (a) between the work piece (b) and the axis of rotation of the tool (c). 7. The milling tool for carrying out the method according to claims 1 to 5, for the manufacture of a concave surface from a workpiece for plastic spectacle lenses, characterized in that it is configured in a discoidal relation to its rotation form and provided with a multiplicity of support arms uniformly distributed on the perimeter, and on whose outer ends are fixed cutting plates which are directed radially in relation to the axis of rotation (c) of the milling tool and whose edges define a toric envelope surface. The milling tool according to claim 7, characterized in that the cutting plates can rotate about their center and are fixed in the rotational position to the support arms.