JPH0154169B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lens centering machine, and more particularly to a lens centering machine that determines the outer diameter of a lens by limiting the cut of a grindstone into a centered lens by a stopper screw. be.

Conventionally, as shown in Fig. 1, such a centering machine has a spindle A rotated by a power source supported on a grindstone arm B, a grindstone C attached to the spindle A, and an arm B pivoted on a machine base D with a pivot E. Arrived,
The lens G is attached with the optical axis aligned with the lens rotation axis F rotated by the power source, that is, the lens to be ground is centered, and the protrusion H provided on the arm rotates in conjunction with the lens rotation axis F. Top dead center of cam I ₁
When in contact with the lens G, the grinding wheel C occupies the position shown by the solid line, and as the cam I rotates, the arm B is pulled by the spring J and swings about the axis E, so that the grinding wheel C approaches the lens G, and the cam Before the bottom dead center I ₂ of the lens reaches the protrusion H, the stopper surface K provided on the arm B comes into contact with the tip of the stopper screw M screwed into the shaft stand L that supports the lens rotation axis F, and this causes the grinding wheel to move against the lens. The outer diameter of the lens is determined by limiting the notch. In a centering machine equipped with such a lens outer diameter determining mechanism, the final position of the grinding wheel in contact with the outer periphery of the lens is determined by wear of the grinding wheel during lens grinding, or by thermal effects due to the power energy of the power source and room temperature. Therefore, it was necessary to frequently manually perform a series of operations: sampling the ground lens, measuring the outer diameter of the sampled lens, and adjusting the position of the stopper screw based on the measurement results. As a result, measurement reading errors and stopper screw adjustment errors occur, contributing to a decrease in the accuracy of the outer diameter of the ground lens. We also attempted a method of numerically controlling the cut of the grindstone into the lens according to general NC technology, but even with this method, it was difficult to program information regarding uncertain factors such as grindstone wear and thermal effects. Errors are likely to occur, and in addition, since the entire grinding wheel arm is moved by numerical control, a grinding wheel feeding device and NC device, which are largely modified from the conventional grinding wheel arm swing mechanism, are required, making the entire centering machine large-scale and expensive. Summer.

An object of the present invention is to provide a lens centering machine that solves the above-mentioned problems by improving the lens outer diameter determining mechanism in the conventional centering machine.

According to this invention, when consecutively centering a plurality of lenses, an electric control mechanism or a servo mechanism is incorporated into the stopper screw that comes into contact with the stopper surface that moves with the grindstone to determine the outer diameter of the lens. The positioning of the stopper screw is automatically adjusted to compensate for grinding errors caused by wear of the grinding wheel or thermal effects on the lens that has finished grinding, and the cut of the grinding wheel into the lens to be processed later is automatically corrected without error. A centering machine is provided.

Embodiments of the invention will be described below with reference to the drawings. In FIGS. 2 and 3, 1 is one bell clamp shaft rotatably supported on the shaft stock 2, 3 is the other bell clamp shaft rotatably supported on the other shaft stock 4 and facing the shaft 1; 5 and 6 are respectively axis 1
and 3, and the lens 7 is
According to the prior art, the reduction transmission device 8 is sandwiched under pressure between two coaxial gears, is centered with the optical axis aligned with the gear axis, and is driven from a power source (not shown) to a reduction gear transmission device 8.
and shafts 1, 3 and Yatoi 5, which rotate through
Rotates with 6. 10 is a grindstone; 11 is a reduction transmission device 12 that fixes the grindstone 10 to one end and connects the power source with the grindstone 10;
13 is a grindstone arm that supports the spindle and is swingably attached to a stage 15 fixed to the machine base 14 via a pivot 16; 17 is a spindle 4 fixed upright to the base 14; and a tension spring provided between the arm 13 and the arm 13, 18
is rotatably supported on the shaft stand 4 and is connected to the bell shafts 1 and 3.
and a cam that rotates in conjunction with the Yatoi 5 and 6, the lens 7 having a constant ratio for one rotation of the cam,
For example, when the cam 18 rotates at a ratio of 1:6 to 1:9 and rotates once, one process of cutting the lens 7 is completed. The rotation of the cam 18 is caused by the grinding wheel arm 1.
The information is transmitted to the grindstone arm and eventually to the grindstone 10 via the follower pin 19 fixed to pin 1. As the cam rotates, the grindstone arm 13 swings around the pivot 16, and the pin 1
As 9 contacts the cam from the top dead center to the bottom dead center,
The grindstone arm 13 is drawn toward the spindle 4, and the grindstone 10 approaches the lens 7. Before the bottom dead center of the cam reaches the pin 19, the stopper surface 20 provided on the grindstone arm comes into contact with the tip of a stopper screw 30 (described later), and the grindstone arm 13 is prevented from pivoting further toward the spindle 4. , so that the grinding wheel 1 for the lens
The outer diameter of the lens 7 is determined by the zero cut being limited and the lens 7 rotating one or more times in this state. During this time, the cam 18 has pin 1 near the bottom dead center.
Rotate while staying away from the tip of 9. After the outer diameter of the lens is determined, as the top dead center of the cam moves toward the pin 19, the pin 19 contacts the cam 18 and the arm 1
3 swings in the opposite direction against the spring 17, the grindstone 10 moves away from the lens 7, and one process ends when the top dead center of the cam reaches the pin 19 and rotates once. The above structure and operation are similar to the corresponding mechanism including the grindstone arm swing mechanism in a conventional centering machine.

In FIG. 4, the stopper screw 30 is
is slidably fitted into a bushing 31 fixed to the
Further, rotation is prevented by a pin 33 fitted into a vertical groove 32 bored on the outer periphery of the screw and fixed to the bushing 31, and the threaded portion 36 of the connecting rod 35 is screwed into the threaded portion 34 provided inside the stopper screw 30. I'm wearing it. A pulse motor 38 is attached to the shaft stand 4 via a stay 37, and an output shaft 39 of the motor is connected to a connecting rod 35. When the motor 38 rotates,
As the connecting rod 35 rotates, the stopper screw 30 moves back and forth relative to the stopper surface 20, that is, linearly moves. Alternatively, a ball screw may be used, and the motor output shaft 39 may be attached to the threaded rod of the ball screw, and the stopper screw 30 may be attached to the nut, and the rotation of the motor 38 may be converted into linear motion of the stopper screw 30.

In FIG. 5, the contact points 43 and 44 are attached to the upper and lower flanges 41 and 42, respectively, of the U-shaped contact point holder 40 that is open to the side, and the contact points are used to attach the lens 7 that has been ground by the upper and lower contact points to the caliper. A detector that contacts the outer periphery of the lens with the measuring pins 43a and 44a of each probe moving up and down in accordance with the outer diameter of the lens, and converting this displacement into an electrical signal using, for example, a differential transformer. It is becoming. Further, the holder 40 is movable between a measurement position shown by a solid line in FIG. 5 and a standby position shown by a dotted line. 50
is an electrical box containing an electric circuit that compares the input signal from the probe with a reference signal matching the desired lens outer diameter and rotates the motor 38 according to the result. In the electrical equipment box 50, 51
52 is a circuit that adds the input signal A from the measuring head 43 and the input signal B from the measuring head 44 to generate a measured value proportional signal, and 52 receives the measured value proportional signal from the circuit 51 and visually displays the measured value. 53 is a circuit that sets an electrical signal of a reference value that matches the desired lens outer diameter and applies it to a comparison circuit 54, which compares the measured value signal from circuit 51 with circuit 5.
The pulse oscillation circuit 55 is a circuit that compares the reference value signal from 3 and determines whether the cut lens is larger, smaller, or equal to the reference, and applies a corresponding control signal to the pulse oscillation circuit 55. In response to the control signal from the comparison circuit 54, a signal with a number of pulses proportional to the difference between the outer diameter reference value and the measured value is generated, and a determination signal indicating whether the outer diameter reference value is larger or smaller than the outer diameter reference value is applied to the drive circuit 56. The circuit and drive circuit 56 is a circuit that selects whether the pulse motor 38 should be rotated forward, reverse, or stopped according to the pulse number signal and the determination signal, and then transmits an output signal to the motor 38 according to the number of pulses. The pulse motor 38 is connected to the electrical box 5
It rotates forward or backward according to the output signal from 0, and rotates angularly by an amount proportional to the number of pulses, thereby positioning the stopper screw 30 of the lens to be processed later.

In the centering machine according to this embodiment configured as described above, the gauge head holder 40 is placed at the position shown by the solid line in FIG. When measuring the outer diameter of the lens after completing the process, for example, if the cut of the grindstone into the lens is shallow due to wear of the grindstone, the comparison circuit 54 detects that the measured value is larger than the reference value, and the pulse oscillation circuit 55 and the drive circuit 56, the pulse motor 38 rotates in the normal direction by an amount corresponding to the difference from the reference value, and this causes the stopper screw 30 to move back and the positioning adjustment of the stopper screw is automatically performed. The arm 13 swings further under the tension of the spring 17 until it comes into contact with the automatically adjusted stopper screw 30, and the cut of the grindstone into the lens to be processed later is corrected until it becomes the proper amount. When the comparison circuit 54 detects that the outer diameter of the ground lens is smaller than the reference value, the pulse motor 38 is reversed by the pulse oscillation circuit 55 and the drive circuit 56, and the stopper screw 30 moves forward to cut the grindstone. is corrected, and thereafter the lens outer diameter that matches the reference value is determined. If the measured value and the reference value match in the comparison circuit 54, there is no output signal from the drive circuit 56, so the pulse motor 38 and the stopper screw 30 remain stopped.

In the centering machine according to this embodiment, the centering of the lens may be performed using an exchange shaft method instead of the illustrated bell clamp method. The probe may be of any type as long as it converts the displacement or outer diameter of the lens into an electrical signal. The probe holder is preferably of a type in which the measurement position and standby position can be shifted for convenient attachment and detachment of the lens. The input signal from the probe to the electrical box may be digital or analog. In the case of an analog signal, an A/D converter is provided in the electrical box to convert it into a digital signal. The motor may be a DC or AC servo motor in addition to a pulse motor; in this case, the signal from the probe is analog, and an amplifier circuit is provided in the electrical box instead of the pulse oscillation circuit.

As explained above, the present invention is a lens centering process in which a plurality of lenses are successively subjected to a lens centering process in which the cut of a grindstone into a centered lens is limited by a stopper screw to determine the outer diameter of the lens. In the machine, at least one device measures the outer diameter of the lens after grinding and converts it into an electrical signal.
an electrical circuit that compares this electrical signal with a reference electrical signal that matches the desired lens outer diameter and generates an output signal based on the comparison; The motor is equipped with a motor that rotates or stops and moves the stopper screw back and forth by an amount that needs to be corrected in order to correspond to the lens to be processed later. It is possible to improve the outer diameter accuracy of the processed lens by eliminating adjustment errors caused by the process and automatically correcting the cut of the grindstone into the lens to be processed without error. A centering machine having an automatic adjustment function can be constructed at low cost without making any changes to the grindstone arm swing mechanism.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the configuration of a conventional lens centering machine, Fig. 2 is a plan view of a lens centering machine according to the present invention, and Fig. 3 is a partially cutaway view taken along the - line in Fig. 2. Figure 4 is a side view of Figure 2.
FIG. 5, which is an enlarged sectional view taken along the line, is a block diagram showing a lens outer diameter detecting section for automatic stopper screw adjustment and an electric circuit inside the electrical equipment box. 1 and 3...Bell clamp shaft, 7...Lens,
10... Grindstone, 13... Grindstone arm, 17... Spring, 18... Cam, 20... Stopper surface, 30...
...Stopper screw, 38...Motor, 43, 44...
...Measurement head, 50...Electrical box.

Claims (1)

[Scope of Claims] 1. In a lens centering machine that sequentially performs lens centering processing on a plurality of lenses in which the cut of a grindstone into a centered lens is limited by a stopper screw to determine the outer diameter of the lens. , at least one probe that measures the outer diameter of the lens that has been ground and converts it into an electrical signal, and compares this electrical signal with a reference electrical signal that matches the desired lens outer diameter; an electric circuit that generates an output signal based on the output signal; and an electric circuit that rotates in the forward or reverse direction or stops depending on the output signal, and moves the stopper screw back and forth by an amount that is to be corrected to correspond to the lens to be processed later. A lens centering machine characterized by comprising a moving motor.