JPS6247149B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tool stand feed control device that uses a servo motor to rapidly feed a tool stand.

In a tool table feed control device that performs rapid feed and machining feed by a single servo motor without using a rapid feed cylinder, for example, a tool table feed control device for a numerically controlled grinding machine, a rapid feed forward command is issued based on numerical control data. or when the rapid traverse forward switch is activated during manual operation, a number of rapid traverse forward pulses are given to the servo motor according to the preset rapid traverse movement amount to rapidly traverse the tool platform to a predetermined position. I'm trying to move it forward. In such conventional devices, not only is it not possible to mechanically regulate the position of the forward end of rapid traverse, but also the rapid traverse operation is based on numerical control data and the command from the manual operation switch. Because there is no interlock with the rapid traverse operation, automatic operation is interrupted when the tool table is advanced rapidly by automatic operation using numerical control data, and after this, the operator accidentally turns the rapid traverse forward switch. If the tool stand is operated at the rapid traverse forward end position, the tool stand may move forward again at the rapid traverse speed and damage the tool or workpiece.

In addition, even if automatic operation based on numerical control data is started with the tool carriage advanced by operating the rapid traverse advance switch, the tool carriage will advance again at the rapid traverse speed from the rapid traverse forward end position and the tool or damage the workpiece.

Furthermore, in tool rest feed control devices such as numerically controlled grinders, the original position of the tool rest and the position of the rapid forward advance end are changed depending on the workpiece diameter, etc., so a limit switch is used to adjust the tool rest to the original position. It was difficult to perform security using a limit switch because it was not possible to detect the position or the position at the forward end of rapid traverse.

In view of these conventional problems, the present invention makes it possible to perform interlock between fast-forward control based on numerical control data and fast-forward control based on manual switch operation without using any limit switches. Once fast forward movement is performed in response to a switch operation, neither fast forward movement based on numerical control data nor rapid forward movement based on manual switch operation is performed. Examples thereof will be described below with reference to the drawings.

FIG. 1 shows a tool stand feeding mechanism of a numerically controlled grinding machine, and shows a tool stand 11 on which a grinding wheel 10 is rotatably mounted.
A feed screw 13 is screwed into a nut 12 fixed to the lower surface, and one end of the feed screw 13 is supported by a slide base 15 placed on a bed 14, and is It is connected to a servo motor 18. This servo motor 1
Reference numeral 8 is a device whose rotation is controlled according to a feed command pulse, and a pulse motor or a DC motor can be used.

FIG. 2 shows a control circuit for controlling the rotation of the servo motor 18, in which SW1 represents a manual switch for commanding fast forward forward movement, and SW2 represents a manual switch for commanding rapid forward movement backward. The signals sent from these manual switches are sent through OR gates OG1 and OG2 together with a rapid forward command signal RAD or a rapid backward command signal RRE sent from a decoder (not shown) that decodes the command data given to the numerical control table. ANDGATE AG
Flip-flop FF1 is applied to the inputs of 1 and AG2, and the outputs of these AND gates AG1 and AG2 are used to store the fact that the tool rest 11 is in rapid forward movement. The flip-flop FF2 is set respectively.

20 generates a pulse at a fast forward speed while the set output signal output from these flip-flops FF1 or FF2 is applied via the OR gate OG3, and sends this pulse to the AND gate AG.
3. Pulse generation circuit for AG4, consisting of a VF converter, etc. said and gate
AG3 is open while flip-flop FF1 is set and outputs the pulse from the pulse generating circuit 20 as a positive command pulse for commanding forward movement, and AND gate AG4 is open while flip-flop FF1 is set.
It is opened while the pulse generating circuit 20 is set, and outputs a negative command pulse that commands the pulse from the pulse generating circuit 20 to retreat. These command pulses, together with command pulses from the manual pulse generator 21 and slow feed pulses SAP and SRP sent from a grinding feed pulse generation circuit (not shown) during automatic operation, are used to drive the servo motor via OR gates OG6 and OG7. The current position display of the tool stand 11 is changed at the same time as the servo motor 18 is rotated at a rapid traverse speed to move the tool stand 11 forward or backward.

23 is a detection counter for detecting the completion of fast forwarding, and a preset counter or the like is used. This detection counter 23 is a detection circuit 2 that detects when either flip-flop FF1 or FF2 is set.
When a load signal with a predetermined time width is output from 4,
The rapid forward movement amount set in the setting device 25 is set as a preset value, and then the preset value is decreased by receiving a positive or negative command pulse via the OR gate OG5. When the preset value becomes zero, the preset value is Outputs a time width borrow signal BS. This borrow signal BS is applied to flip-flops FF1 and FF.
2 is applied to the reset terminal R of the flip-flop
It is designed to reset FF1 and FF2,
When the borrow signal BS is output, the sending of fast-forward pulses is stopped. Therefore, switch SW1,
Command signal RAD for rapid traverse forward and rapid traverse backward given as SW2 operation or numerical control command,
When flip-flop FF1 or flip-flop FF2 is set by RRE, positive or negative command pulses are outputted to the drive circuit 21 in a number corresponding to the rapid forward movement amount set in the setting device 25, and the tool rest 11 is moved to a predetermined position. Moved forward or backward by the rapid feed amount. Note that 26 is a delay circuit that delays the reset timing of flip-flop FF2 by a small amount of time.

Further, 27 is a latch relay that memorizes that the grinding wheel head 11 has left its original position, and energizes the latch coil LC by operating the switch SW1 or receiving the rapid forward command signal RAD, and flips the flip-flop.
When FF2 is set, the detection counter 23
The unlatch coil is activated by the signal from AND gate AG5 which detects that a borrow signal is output from
It is starting to energize ULC. For this reason,
This latch relay 27 is latched when the tool stand 11 starts moving forward due to the operation of the switch SW1 or reception of the rapid traverse advance command signal RAD, and this latched state is maintained until the tool stand 11 is retreated from the rapid traverse forward end and returns to the original position. be done. The signal output from the normally open contact 27a of this latch relay 27 is directly given to the AND gate AG2, and
It is applied to AND gate AG1 via inverter INV1, and latch relay 27
AND gate AG1 is closed while switch SW1 is in the latched state, flip-flop FF1 is not set even if switch SW1 is actuated, and flip-flop FF1 is not set even if rapid forward command signal RAD is applied.
1 is not set. Therefore, when the tool stand 11 is located at the rapid forward forward end, even if the operator accidentally operates the manual switch SW1 for rapid forward movement, the rapid forward movement of the tool stand 11 will not be restarted; Even if a program operation is started without performing a grinding wheel table original position return operation after a power outage or an emergency stop, the tool table 11 can be prevented from moving forward at the rapid traverse speed from the position of the rapid traverse forward end.

The circuit constituted by the switch SW3 and the OR gate OG9 is for manually unlatching the latch relay 28, and the latch relay 28 is unlatched after the grinding wheel head 11 is positioned at its original position prior to the start of operation. used for.

In addition, in the above embodiment, the latch relay is used to remember that the tool stand has left its original position.
The memory of the tool stand leaving its home position was not lost even if a power outage occurred, but when the control circuit was configured with a computer, a specific bit in the core memory was used instead of a latch relay to prevent the tool stand from leaving its home position. A similar effect can be achieved by remembering things.

As described above, the tool table feed control device of the present invention includes a storage means for storing the fact that rapid forward movement has been carried out, and a storage means for storing the fact that rapid forward movement has been performed, and whether a rapid forward movement command is given based on numerical control data or When fast forward forward movement is started in response to the switch being operated, a setting means for setting the storage means to a specific state and a fast forward backward pulse set in advance being sent out from the fast forward pulse generating means are set. Since a reset means for detecting and resetting in the memory means is provided, and generation of the fast forward command pulse is started only while the memory means is in the reset state, the position detector such as a limit switch can be used to control the position of the tool rest. Even in cases where the home position cannot be detected, it is possible to ensure that rapid forward movement is only started when the tool rest is at the home position, as well as rapid forward control based on numerical control data commands and manual switch commands. It is also possible to interlock with fast-forward control. Therefore, regardless of whether the tool stand is moved forward in rapid traverse based on a command from numerical control data or whether the tool stand is moved forward in rapid traverse by operating a manual switch, the tool stand will move forward again at the rapid traverse speed from the forward end position of rapid traverse. This can prevent damage to tools and workpieces.

Furthermore, since the storage means is set immediately after responding to the fast forward forward command, even if fast forwarding is interrupted in the middle of fast forwarding, the
There is an advantage that it is determined that fast forwarding has been performed and that it is possible to reliably prevent fast forwarding from being performed again.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; FIG. 1 is a cross-sectional view of essential parts showing the feeding mechanism of the grindstone head, and FIG. 2 is a diagram showing an electric circuit for controlling the rotational speed of the servo motor 18 shown in FIG. 1. be. 11... Tool stand, 18... Servo motor, 20
... Pulse generation circuit, 19 ... Drive circuit, 23 ...
...Detection counter, 25...Setting device, 27...Latch relay, AG1 to AG5...And gate, FF
1, FF2...Flip-flop, INV1...Inverter, OG1 to OG9...OR gate, SW
1, SW2...Manual switch.

Claims (1)

[Claims] 1. In a tool stand feed control device equipped with a rotary servo motor that controls the feed of the tool stand in accordance with the feed command pulse, a rapid forward command generated based on numerical control data or a means switch for the rapid forward forward command is output. In response to the signal, a number of fast-forward forward pulses corresponding to a preset fast-forward movement amount are given to the servo motor, and a fast-forward backward command generated based on numerical control data or a manual switch for fast-forward backward is output. a fast-forward pulse generating means for supplying the same number of fast-forward backward pulses as the preset fast-forward forward pulses to the servo motor in response to a signal sent to the servo motor, a storage means for storing that the fast-forward forward movement has been performed, and numerical control data. a setting means for setting the storage means to a specific state at the same time as the fast forward movement is started in response to a fast forward forward command being given based on the fast forward forward command or the switch for the fast forward forward command being operated;
a reset means for detecting that a preset fast-forward backward pulse is sent out from the fast-forward pulse generating means and resetting the memory means; and a fast-forward forward movement by the fast-forward pulse generating means while the memory means is in the set state. A tool stand feed control device comprising: a control means for preventing pulse sending from being restarted.