JP2742482B2 - Glass lens press molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass lens press molding machine.

[0002]

2. Description of the Related Art When a glass lens is formed by pressing, as shown in FIG. 5, a preform 1 of a lens to be formed is placed between an upper mold 3 and a lower mold 4 in a body mold 2 and is heated to a high temperature. After heating, the upper mold 3 is lowered and pressed to transfer the spherical surface formed on the mold to the preform 1.

In a conventional glass lens press molding machine, as shown in FIG. 1, for example, a pneumatic cylinder 7 having rods 5 and 6 extended at both ends is used as a press driving device. A spacer 9 is inserted between the upper die 3 and the upper die 8 to prevent the rod 6 for pushing the upper die 3 from falling by a predetermined amount or more during pressing. Was.

[0004]

According to such a molding machine, the preform 1 is always pushed to the maximum pushing position with a constant thrust at the time of pressing. However, since the size of the preform 1 varies,
When the indentation was performed under the same conditions, cracks were generated or the accuracy was sometimes reduced. Therefore, in order to prevent this, the maximum pushing position is adjusted according to the size of the preform 1. However, not only the above problem cannot be sufficiently solved but also the adjustment is troublesome and the lens productivity is reduced. There was a problem of lowering.

The present invention has been made in view of the above circumstances, and is intended to provide a glass lens press capable of efficiently forming a lens without causing cracks or a decrease in accuracy regardless of variations in the size of the preform. An object is to provide a molding machine.

[0006]

SUMMARY OF THE INVENTION The present invention provides a reciprocating pneumatic cylinder having working pressure chambers on both sides of a piston, wherein a spool moved by an electric motor in a moving direction of the piston is provided inside the piston. The spool and the piston constitute a spool valve that controls the air pressure balance of the two working pressure chambers. When a positional deviation occurs between the spool and the piston, the two valves are actuated by the action of the spool valve. An electro-pneumatic servo actuator that operates to follow the movement of the spool so that the air pressure balance of the pressure chamber changes and the piston eliminates the positional deviation, and is positioned by a drive rod extending from the piston of the electro-pneumatic servo actuator. And a driven glass lens forming press die, and a position detector for detecting the position of the driving rod A force detector that detects an axial load acting on the drive rod, and a control device that drives and controls the electric motor based on detection signals of the position detector and the force detector. It is a solution to the problem.

The control device includes a position control mode for controlling the drive of the electric motor based on the detection signal of the position detector, and a force control mode for controlling the drive of the electric motor based on the detection signal of the force detector. And a control mode.

[0008]

In the glass lens press forming machine of the present invention, a newly developed electro-pneumatic servo actuator is used, and the position of the spool is moved by an electric motor so that the piston follows the position of the spool. Configured. Then, a press die for forming a glass lens is driven by a drive rod extending from the piston, and the glass lens is formed. In this case, the control device
Since the electric motor is controlled based on each detection signal of the position detector for detecting the position of the drive rod and the force detector for detecting the load, the position and force of the drive rod can be adjusted with high accuracy.

[0009]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the entire configuration of a press molding machine according to an embodiment of the present invention. In FIG.
0 is an electro-pneumatic servo actuator. The electro-pneumatic servo actuator 100 has been newly developed recently, and will be described in detail later. A first airtight chamber (operating pressure chamber) 138 and a second airtight chamber (operating pressure chamber) are provided on both sides of the piston 104. Inside the piston 104 of the reciprocating pneumatic cylinder having 140, a spool 112 which is moved along a moving direction of the piston 104 by a stepping motor (electric motor) 128 is incorporated.
A spool valve for controlling the air pressure balance between the airtight chambers 138 and 140 by the piston 12 and the piston 104 is formed.

In the actuator 100, when the stepping motor 128 is driven to move the spool 112, the air pressure balance between the first airtight chamber 138 and the second airtight chamber 140 is changed by the action of the spool valve, and the piston 104 is moved.
However, the operation follows the movement of the spool 112 so as to eliminate the positional deviation between the spool 112 and the piston 104.

The actuator 100 includes a piston 1
It is arranged above the glass lens forming press mold 20 with the drive rod 108 extending from 04 facing downward. The press die 20 includes a body die 2, an upper die 3 and a lower die 4. The lens preform 1 can be formed by pushing the upper die 3 with a drive rod 108.

The present molding machine also includes a drive rod 10
8, a position detector 30 for detecting the position of
A load cell (force detector) 40 for detecting an axial load acting on the actuator 8, a control device 50 for driving and controlling a stepping motor 128 of the actuator 100 based on detection signals from the position detector 30 and the load cell 40, and a control device. And a motor amplifier 60 for amplifying the output signal of the step 50 and inputting the amplified signal to the stepping motor 128.

Next, the details of the above configuration will be described.

First, the details of the control device 50 will be described with reference to FIG.

Since the actuator 100 is configured to be driven by rotating the stepping motor 128, the control device 50 calculates the operation amount of the stepping motor 128 and outputs it to the motor amplifier 60.

The driving rod 108 of the actuator 100
, A position detector 30 and a load cell 40 are attached, and their detection signals P1 and P2 are fed back to the control device 50. The control device 50 includes a position control system operation unit 51, a force control system operation unit 52, and a command value generation unit 53.

The position control system operation section 51 calculates a position command value P4 from the speed command value P3 from the command value generation section 53, and calculates the position command value P4 and the signal P from the position detector 30.
A signal P6 obtained by multiplying a deviation P5 from 1 by a gain and a signal P7 obtained by multiplying the speed command value P3 by a gain are added to calculate an operation amount P10 of the stepping motor 128.

On the other hand, the force control system calculation unit 52 multiplies the deviation P9 between the force command value P8 from the command value generation unit 53 and the signal P2 from the force detector 40 by PI (proportional + integral) to perform stepping. The operation amount P20 of the motor 128 is calculated.

The control device 50 has a means 55 for selecting one of the position control mode and the force control mode in addition to the above-mentioned elements. The selection means 55 selects one of the two operation amounts P10 and P20 according to the control mode switching signal P30 from the command value generation unit 53, and inputs the selected operation amount signal to the motor amplifier 60. Then, a drive signal is input from the motor amplifier 60 to the stepping motor 128.

Next, the electro-pneumatic servo actuator 1
00 will be described with reference to FIG.

A piston 104 is incorporated in a cylindrical cylinder body 102 in an airtight and slidable manner. A sleeve 106 is integrally fixed to the piston 104 coaxially, and a drive rod 108 for pushing the upper mold 3 is integrally connected to the sleeve 106. The drive rod 108 penetrates the bottom surface 102A of the cylinder body 102 and is slidably supported by a bearing 120B. Reference numeral 110 denotes a rod seal.

A spool 112 is incorporated in the piston 104, specifically, in the sleeve 106 integrated with the piston 104 so as to be slidable in the same direction as the piston 104 slides. I have. This spool 112
Is provided with a key 114 for stopping rotation.
Further, a stopper 116 is provided for limiting the displacement of the spool 112 with respect to the piston 104 in the axial direction.

A nut 118 is fixed to the spool 112, and a ball screw shaft 120 is screwed thereto.
The shaft end of the ball screw shaft 120 is the bearing 12
2, it is rotatably attached to a cover 132 and is connected to a stepping motor 128 via a coupling 124.

The stepping motor 12 of the piston 104
On the 8th side, a keyway 130 is cut, and a cover 132
The piston 1 is engaged with the key 134 fixed to the piston 1.
04 is guided for sliding and rotation is prevented.

Passages 151 to 158 through which air passes are provided inside the cover 132, the piston 104, and the sleeve 106, and first and second passages formed by the piston 104 in the compressed air source 136 and the cylinder body 102.
The airtight chambers 138 and 140 and the atmosphere 142 are connected to each other. These passages 151 to 158 are respectively formed by grooves 112A and 112B formed on the outer periphery of the spool 112 depending on the position of the spool 112.
The configuration is such that the flow direction of the air passing through 58 is switched.

Next, the operation of the molding machine of this embodiment will be described.

First, the actuator 100 will be described. In FIG. 3, when the stepping motor 128 rotates clockwise as viewed from the shaft side, the ball screw shaft 1
20 also rotates integrally. This ball screw shaft 12
A nut 118 screwed into the nut 0 is fixed to a spool 112, and the spool 112 is detented with respect to the piston 104 by a key 114, and the piston 104 is rotated with respect to the cover 132 by a key 134. It has been stopped. Therefore, the nut 118 eventually starts to advance by the rotation of the ball screw shaft 120. Further, the spool 112 is also integrally advanced by the advance of the nut 118. As a result, the groove portions 112A and 112B of the spool 112 and the passage 154 of the sleeve 106 are formed.
１５156. Therefore, the passage 15
1. Since the first airtight chamber 138, the passages 152 and 153, and the groove 112A of the spool 112 are closed spaces, the inflow of air from the compressed air source 136 is prevented.

On the other hand, the air in the second hermetic chamber 140 is
4, 155, groove 112B, passages 156, 157, 15
Emitted through 8 to the atmosphere. Therefore, the air pressure in the second hermetic chamber 140 decreases, and the force balance in the front-rear direction of the piston 104 is lost, and the piston 104
6. Advance with the drive rod 108. However,
Since the spool 112 does not move with them, when the deviation between the grooves 112A and 112B of the spool 112 and the passages 154 to 156 of the sleeve 106 becomes zero again, the outflow of air from the first airtight chamber 138 stops, and the piston 104 Stops moving.

As a result, when the ball screw shaft 120 is rotated by the stepping motor 128 and the nut 118 is positioned at an arbitrary position, the driving rod 108 is slid and positioned corresponding to the axial position thus positioned. Become.

Conversely, when the stepping motor 128 rotates counterclockwise and the spool 112 retreats, the spool 1
12, a deviation occurs between the grooves 112A and 112B and the passages 154 to 156 of the sleeve 106 on the opposite side from the forward side, so that the release of the air in the second hermetic chamber 140 to the atmosphere 142 is prevented, and the compressed air source The air in the first hermetic chamber 138 communicating with the 138 flows through the passages 152 and 153, the groove 112A,
The gas flows into the second hermetic chamber 140 via the passages 155 and 154. As a result, the air pressure in the second airtight chamber 140 increases, the force balance in the front-rear direction of the piston 102 is lost, and the piston 104 retreats. Due to this retreat, the passages 154 between the grooves 112A and 112B of the spool 112 and the sleeve 106 are formed.
When the deviation from .about.156 becomes zero again, further movement of air is prevented, and the retreat of the piston 104 is completed.

The position and load of the drive rod 108 are detected by the position detector 30 and the load cell 40 in real time. These detection signals are input to the control device 50 as feedback signals, and the stepping motor 128 is controlled based on the signals. With such a feedback control system, the position of the drive rod 108 and the force for pushing the upper die 3 are adjusted with high accuracy.

Next, a control operation for actually forming a glass lens will be described.

The basic operation cycle of the actuator at the time of molding the glass lens is configured as shown in FIG. 4 as an example. The operation cycle is divided into three stages. The first stage moves from the initial position S0 to the heating position S1,
This is a process until the preform is heated at the heating position S1. The second stage is a process in which heating is completed and the lens is actually pressed. The third stage is a process of terminating the press and returning to the initial position S0.

In the first and third stages, the actuator 100 is driven in the position control mode. That is, the operation amount signal P1 calculated by the position control system calculation unit 51
Drive control is performed based on 0. On the other hand, in the second stage, switching from the position control mode to the force control mode is performed at a certain point. That is, first, the drive rod 108 is driven and lowered in the position control mode. When the drive rod 108 comes into contact with the upper mold 3, a load is generated, and when the drive rod 108 is further lowered, the load gradually increases. When the load exceeds the position / force control switching point F0, a control mode switching signal is output to switch the control method, and thereafter, the drive is performed in the force control mode. That is, the actuator 100 is driven based on the operation amount signal P20 calculated by the force control system calculation unit 52.

Here, the force command value P8 in the force control mode is changed and input in several steps, and the next step command is input after each set time has elapsed. Then, when the set time of the last stage elapses, the control method is switched again to the position control mode, and the process proceeds to the third stage. Note that even during execution of the force control mode, the control device 50 monitors the signal from the position detector 30 and ends the second stage even within the set time when it reaches the maximum depressed position.

Here, the initial position S0 and the heating position S in FIG.
1, maximum pushing position S2, and moving speed command value v1,
v2, v3, position / force control switching value F0, press force set values F1, F2, F3, F4 and their press times t
1, t2, t3, and t4 are values given in the operation cycle of the actuator.

In the position control mode, the actuator 100 moves at a speed of 0.5 mm / min to 30 m.
The driving rod 108 is moved at a low speed of m / min to achieve a positioning accuracy of ± 10 μm. In the force control mode, control is performed with an accuracy of 2% of the maximum thrust. These values have not been achieved conventionally.

In a molding machine using this actuator,
Since the pressing speed at the start of pressing and the pressing force at the time of pressing can be set arbitrarily, by setting appropriate molding conditions, regardless of the variation in the size of the preform, the lens can be formed without cracking under certain conditions. Can be molded. Further, the operator merely sets each set value (stop position, moving speed, press force, and press time) and does not need to make any other adjustment, so that labor can be saved.

[0040]

As described above, according to the glass lens press forming machine of the present invention, the position of the drive rod of the new actuator is detected by the position detector, and the load acting on the drive rod by the force detector. Is detected, and the drive of the actuator is controlled based on those detection signals, so that the position and force of the drive rod can be adjusted with high accuracy and without requiring any manpower. Therefore, irrespective of the variation in the size of the preform, it is possible to prevent cracking and a decrease in accuracy, and it is possible to efficiently mold the lens.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of one embodiment of the present invention.

FIG. 2 is a diagram illustrating details of a control device according to the embodiment;

FIG. 3 is a detailed sectional view of the electro-pneumatic servo actuator of the embodiment.

FIG. 4 is an explanatory diagram of the contents of position control and force control in the glass lens press molding operation of the embodiment.

FIG. 5 is a view showing a conventional glass lens press molding machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Glass lens preform, 20 ... Press type, 30 ... Position detector, 40 ... Load cell (force detector), 50 ... Control device, 51 ... Position control system operation part, 52 ... Force control system operation part, 55 ... Selection means, 100: electro-pneumatic servo actuator, 104: piston, 108: drive rod, 112: spool, 128: stepping motor (electric motor), 138: first hermetic chamber, 140: second hermetic chamber.

Claims (2)

(57) [Claims] 1. A reciprocating pneumatic cylinder having working pressure chambers on both sides of a piston, wherein a spool which is moved in the direction of movement of the piston by an electric motor is incorporated inside the piston. A spool valve for controlling the air pressure balance of the two working pressure chambers is configured by the above.When a positional deviation occurs between the spool and the piston, the air pressure balance of the two working pressure chambers is changed by the action of the spool valve. An electro-pneumatic servo actuator that operates to follow the movement of the spool so that the piston eliminates the positional deviation, and a glass lens molding that is positioned and pressed by a drive rod extending from the piston of the electro-pneumatic servo actuator. Press die, a position detector for detecting the position of the drive rod, and the drive rod A glass lens press, comprising: a force detector for detecting an acting axial load; and a control device for driving and controlling the electric motor based on detection signals of the position detector and the force detector. Molding machine. 2. The electric motor according to claim 1, wherein the control device controls the driving of the electric motor based on a detection signal of the position detector, and the electric motor based on a detection signal of the force detector. And a force control mode for controlling the driving of the glass lens press molding machine.