JPS5845854A - Spectacle lens grinding machine - Google Patents

Abstract

PURPOSE:To improve the working accuracy and working efficiency of a grinding machine by providing on a lens grinding machine which froms contour of a spectacle lens, a detecting means for detecting the large diameter part of a lens where the feed speed of a whetstone is excessive and by controlling the working speed of revolution of the lens. CONSTITUTION:When a lens 1 to be worked is fixed to a rotary shaft 6, and the periphery of said lens is worked while following, a lens profile pattern 8, a large diameter part (1) of said lens profile pattern 8 is detected during the one revolution of a rotary shaft 6 by means of a control range setting frame 14 provided on a drum 13 rotating coaxially and a contactor 17 fixed to a machine frame 10, and the speed of revolution of the motor 2 is automatically controlled via a speed control device 18 such that the number of revolution of the motor 2 is reduced compared with a normal speed of revolution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a beading machine for machining and measuring the contour shape of a lens into a required die, and particularly to a control device for controlling the rotation of its work shaft.

A Tamazuri machine is a type of profiling machine that cuts or grinds a lens by imitating a die, but the shape of the lens blank before processing (generally circular) is significantly different from the shape of the lens after processing. The distance from the blank center during processing to the finished lens contour differs as shown in Figure 4, so naturally the depth of cut is constant for each lens, so the lens in Figure 4 (B) Like the short axis R1 and the long axis R3
In the case of a lens with a large difference between the two, a rather difficult forced clay tank processing will be performed, imitating the pressure mold. Conventionally, in general wheel grinding machines, the rotational speed of the workpiece axis during machining is constant, so the peripheral speed of the lens surface in contact with the grinding wheel, that is, the feed speed, constantly changes during one rotation of the lens. Depending on the die, quite large cutting resistance may be applied. Lenses processed under such conditions often have a rough finished surface, a shape that does not match the mold, and cracks or chipping of the lens edge may occur. To avoid such lens damage, please take the following precautions when processing plastic lenses.
In pressure mold profiling machining using tx heavy cutting, there is a method of gradually machining by installing a cam to avoid extreme cuts, but the cam design is complicated and when machining a large variety of lenses in small quantities, the cam The side work for using it becomes troublesome. In addition, in general, in a ball-sliding machine using a whetstone grinder, the downward pressure exerted on the work shaft head due to its own weight is adjusted to alleviate the resistance applied to the lens, but the shape of the press die is extremely unusual (see Figure 4). In cases like (b), the scanning accuracy is also inaccurate.

In order to improve the above-mentioned shortcomings of the general milling machine, the vibration of the workpiece shaft during heavy grinding is detected by a detection device such as a crystal pickup or magnetic pickup installed in the milling shaft head. During the period of vibration, the work shaft is automatically stopped, and the part is immediately ground until the vibration stops (until the grinding wheel no longer contacts the lens).
When the vibration stops, the stop of the output signal from the detection device activates the detector, and the work shaft rotates slightly until vibration occurs again due to lens grinding. A beading machine with an automatic control device is known that grinds the entire circumference of a lens by repeatedly starting and stopping the motor in this manner.

However, in this control device, since the motor is started and stopped frequently, small irregularities occur on the outer surface, and the lens is damaged due to vibrations, which remain unsolved.

The present invention eliminates the drawbacks of the conventional aperture machine as described above, improves the finished surface without damaging the lens, improves the accuracy of tracing the outer peripheral shape of the die, and is capable of processing extremely efficiently. The purpose is to provide

- In order to achieve the objective described in F, in the present invention, the pressing part that will be subjected to heavy cutting or heavy grinding is predicted in advance, and when the lens part comes into contact with a rotating milling cutter or grinding wheel, the workpiece is automatically rotated. It is characterized by the provision of an automatic rotational speed control device that changes the angular velocity.

Hereinafter, the present invention will be described in detail according to the embodiments shown in the accompanying drawings.

FIG. 1 is a cross-sectional view of the workpiece shaft portion to which the control range setting device of Honjomei is attached. The lens blank 1 shown in FIG.
It is held by the lens pad 7.7I of the work shaft 5.6 driven through +-5, 4, rotates together with the work shaft 5.6, comes into contact with the cutting edge of the grinding wheel C or the milling cutter, and its outer periphery To be ground or cut. A pressure model 8 is integrally attached to the work shaft 5 with a nut 9 at one end of the work shaft 5 on the side opposite to the lens abutment 7. Work axis 6
is the lens holder/S provided at the right end (not shown)
slide in the axial direction by the handle, sandwiching the lens 1,
It can be removed. The work axis 5.6 is
It is rotatably supported by a bracket 10.11 that descends (upward in the figure) due to its own weight, and is provided with a roller R below the die model 8 (above in the figure), with which the outer periphery of the die model 8 comes into contact. This roller R is rotatably supported by a shaft parallel to the work shaft 5, and the distance between its circumferential surface and the center of the work shaft exactly matches the distance between the circumferential surface of the grinding wheel C and the center of the work shaft 5. is configured to do so. Further, the amount of vertical swinging of the bracket 10.11 is adjusted by a lift handle (not shown), and the distance from the work shaft to the grinding wheel surface and roller surface is adjusted and limited by rotation of the nozzle.

A rotating drum 13 having a T-shaped groove 12 bored on its outer periphery is fixed to the work shaft 5, and a control range setting piece 14 is provided on the outer periphery of the rotating drum 13 and is slidable within the T-shaped groove 12. The control range setting piece 14 can be fixed at any position on the outer circumference of the rotating drum 15 using a square nut 15 and a machine screw 16.

The detection element 17 is a transducer such as a pickup using a crystal or a magnet, and is fixed to the bracket 10, and a contactor 17' at the tip thereof contacts the upper surface of the control range setting piece 14 as shown in FIGS. 1A and 1B. The electrical output signal generated by the contact then enters a speed control device 18, which includes amplifiers, relays, voltage converters, etc., and is configured to vary the rotational speed of the variable speed motor 20. When the detection element 17 leaves the top surface of the control range setting piece 14,
The electric output signal generated again restores the motor 2 to its original rotational speed.

FIG. 2 shows another embodiment in which the rotating drum section is simplified, in which the T-shaped groove 12 of the rotating drum 13 in FIG. In addition, the set screw 13a can be used to arbitrarily rotate the workpiece by a certain angle around the workpiece axis 50 to set it. Therefore, by loosening the set screw 16 and rotating the drum body 15', the relative rotational position with respect to the impression model 8 can be changed. In FIG. 3, two microswitches 17m and 17b are used as detection elements to enable two-stage shifting.

In this case, the part with a wide control range 1. When the contact roller 17a' of one microphone switch 17a comes into contact with the micro switch 17a, and the switch is switched, the variable speed motor 2 becomes the first stage low speed. When the roller 17b1 comes into contact and the switch is switched, the rotation of the motor is switched to the second stage low speed rotation which is even slower than the first stage. In this case, the amplifier in the speed control device 18 can be omitted.

Next, the operation of the above embodiment will be explained. First, Figure 4 (Pi)
A lens blank 1 having a radius Ro is placed between the lens pads 7.710 of the work shaft 5.6 as shown in FIG.
s Press model 8 of the same size as the finished lens with the radius of R2
is fixed to the end of the work shaft 5 with a nut 9. Next, loosen the machine screw 16 on the control range setting device including the rotating drum 15 and the control range setting piece 14, and set the control range setting piece 14 to the fourth position.
Place two pieces on the opposite side rotated by 180 degrees from 1 in Figure (A) and secure them by tightening them with machine screws 16. At this time, the contact of the detection element 17 is set to be next to the machine screw 16. When you start motor 2, boo! The work shaft 5.6 rotates via I-3, 4, the lens blank 1, the mold 8, and the rotating drum 13 begin to rotate together, and the upper surface of the control range setting piece 14 touches the contact of the detection element 17. , the contact vibrates due to friction, and the electric signal from this vibration is sent to the speed control device 1.
8, the motor rotates at a predetermined low speed. Due to the low speed rotation of the motor, the work shaft 5.6 also rotates at a low speed, and when the control range setting piece 14 passes the position of the contact of the detection element 17 (that is, after passing the range of circumference 1 in FIG. 4), the contact Since there is no vibration and therefore the detection signal of the detection element stops, the voltage supplied to the motor of the speed control device 18 is restored.
The rotation of the motor also returns to the rotational angular velocity at startup. The work shaft 5.6 is lowered together with the bracket (10.11), and rough grinding is started from the outer peripheral surface of the lens blank while adjusting the lowering position with a lowering handle (not shown). When the part of the pressure model in the area l in FIG. 4(a) comes into contact with the car roller R, the grindstone C will
The area of the lens that rotates at a low angular velocity is processed into a clay tank, and
range of force; after passing the position of roller R, the rotational angular velocity is 1
The lens is restored to its original state, and a clay tank is processed by following the mold model 8 up to the radius R1 to obtain a lens having the same shape as the mold model. Generally, the circumferential speed is high in the large radius R2 part, and therefore requires heavy cutting, so the rotational speed is reduced to a low angular velocity to prevent the circumferential speed from exceeding the specified value, and the small radius R10 part # or the predetermined speed is Even when grinding is performed, heavy cutting does not occur, and no excessive force is applied to the lens, resulting in smooth and stable machining. If the difference between the small radius R1 and the large radius R3 is extremely large, as shown in Fig. 4←), use the control range setting piece 14 as shown in Fig. 3.
If the width of ゜ is formed into long II, short L and 02 stages, and two detection elements 17a and 17b are provided to create a two-speed transmission, smooth ball toe machining can be achieved similarly to the above-mentioned Fig. 4 P). can be implemented.

As described above, according to the present invention, the position of the control range setting piece 14,141 provided on the rotating drum of the control range setting device attached to the work shaft is adjusted according to the difference in radius of the lens model, This makes it possible to change the rotational speed of the motor, that is, the rotational angular velocity of the work shaft, so compared to the conventional method of repeatedly starting and stopping the motor to perform the sanding process, the sanding machine according to the present invention has the following advantages: The machined surface is smooth, there is no damage such as cracks or chips, the processing efficiency and precision are both good, and handling is extremely simple. Further, the range of angular velocity conversion of the workpiece axis can be changed by simply changing the width of the control range setting pieces 14, 14', which have a simple shape, and the maintenance cost of the tool is low and its handling is extremely easy.

Furthermore, the present invention is effective in improving the processing accuracy even when processing lenses into complex shapes with multiple two-curved points by designing eyeglass frames with improved 77 tension properties. Needless to say.

In addition, in the present invention, the range setting device for changing the speed of the motor may be provided on the rotating drum itself, or may be provided on the ball itself. The speed switching range setting device and its detection device may be constructed by program programming using a microcomputer so that the speed can be controlled.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIGS. 1A and 1B are partially enlarged views of the rotating drum portion of FIG. 1, FIG. 1A is a plan view, and FIG. 1B is a sectional view. 2 is another embodiment of the rotary drum shown in FIG. 1, FIG. 3 is a plan view showing another embodiment of the detection device portion of the present invention, and FIG. 4 is an explanatory diagram of the shape of the lens. 2・・・・・・・・・・・・Filming speed soter 5.6・・・・
・Song・・・Workpiece axis load・・・・Glass model - 13, 14, 14', 15.16・・・・・Song/control range setting device, 17 .17a117b...Song/oil detection element 18... Speed control device Applicant: Takashi Watanabe, representative of Nippon Kogaku Kogyo Co., Ltd.

Claims (1)

[Claims] (1) In an eyeglass lens polishing machine for fixing a lens to be processed on a rotating shaft and processing the periphery of the lens by following a predetermined impression, the shaping machine is capable of processing the peripheral edge of the lens by imitating a predetermined impression. a speed switching range □ setting device for changing the rotational speed of the rotary shaft by a predetermined angular range at the angular position; a detection device for detecting the switching range from the speed switching range setting device; 1. An eyeglass lens polishing machine comprising: a variable speed motor for controlling the rotational angular velocity of the rotating shaft over the predetermined angular range according to an output signal. (2. In the ball-sliding machine according to claim 1, the speed switching range setting device includes a rotary drum (13, 13') attached to a work shaft (5),
A beading machine for eyeglass lenses, characterized in that it comprises a speed switching range setting piece (14, 14') attached to the outer peripheral surface of the lens (13, 13').