JPH0645100B2 - Numerical control grinder - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a numerically controlled grinder that grinds a non-round work piece such as a cam (hereinafter, also simply referred to as “work piece”).

[Prior art]

Conventionally, a method is known in which a numerical control device controls the feed of a grinding wheel in the direction perpendicular to the spindle axis in synchronization with the spindle rotation, and grinds a workpiece such as a cam. To control the feed of the grinding wheel synchronously, it is necessary to add profile data to the numerical controller. This profile data gives the amount of movement of the grinding wheel for each unit rotation angle of the main shaft so that the grinding wheel reciprocates along the finished shape of the workpiece, that is, the profile generating movement. On the other hand, in order to grind a workpiece, in addition to the profile data, machining cycle data for controlling the machining cycle such as feed, cutting, and retreat of the grinding wheel is necessary.
The workpiece is machined on the basis of the machining cycle data and the profile data. Especially, in the case of constant-size grinding, the relationship between the cutting operation and the profile creating motion is important in terms of machining accuracy and machining speed.

[Problems to be Solved by the Invention]

A conventional grinding machine has a function of performing a cutting operation of a tool in synchronism with rotation of a spindle by superimposing it on a profile creating motion. Since the control unit in this case is one cycle of the profile creating motion, that is, one rotation of the main shaft, even if the sizing signal is detected, the cutting cannot be stopped until the control cycle at that time ends. For this reason, there was a problem of cutting too much. The present invention has been made to solve the above problems, and an object of the present invention is to improve the processing accuracy in the constant-size grinding of a non-round work piece.

[Means for solving problems]

The configuration of the invention for solving the above-mentioned problems includes profile data for numerically controlling the tool feed axis with respect to the rotation of the spindle, and causing the profile creation motion of the tool along the finished shape of the non-round work, and the tool. In the numerically controlled grinding machine that processes the non-round workpiece, based on the machining cycle data that controls the machining cycle such as fast-forwarding, cutting, and fast-forward retreating, measure the machining dimensions during machining of the non-round workpiece. A sizing device that outputs a sizing signal when the machining dimension reaches a predetermined value, data setting means for giving cutting data for controlling the cutting operation of the tool to the rotation of the spindle, and the profile. Grinding means for superimposing the cutting data on the data and cutting along with the profile creation motion in synchronization with the rotation of the spindle, and inputting the sizing signal from the sizing device. When the force is applied, the cutting stop means for stopping the cutting of the tool by stopping the superposition of the cutting data and performing only the profile creation motion is provided.

[Action]

FIG. 1 shows the movement trajectory of the tool with respect to the workpiece. O is the spindle axis, W is the workpiece, and G is the tool. The tool G reciprocates in the X direction in synchronization with the rotation of the master in the θ direction, but when viewed from the coordinate system fixed to the workpiece W, the tool G orbits around the workpiece W in the arrow A direction. It becomes an exercise. L is a locus of the center of the tool G when the tool G performs only the profile creating motion with respect to the workpiece W. The cutting data is superimposed on the profile data, and the profile creating motion and the cutting operation that is periodic with the rotation of the main shaft are simultaneously executed. That is, the grinding means is a tool G
Is controlled along a spiral curve M with respect to the curve L, and the workpiece W is ground. And the machining dimensions are measured during grinding,
When the sizing signal is output from the sizing device at the point P2, the superposition of the cutting data on the profile data is stopped, and the cutting stop means stops the cutting of the tool and moves the tool to the position Pe along the curve Lp. Exercise profile creation. Immediately after the sizing signal is detected, only the cutting of the tool is stopped.

【Example】

Hereinafter, the present invention will be described based on specific examples. FIG. 2 is a block diagram showing a numerical control grinding machine. Reference numeral 10 denotes a bed of a numerical control grinding machine, on which a table 11 is slidably arranged. A headstock 12 having a main shaft 13 mounted thereon is arranged on the table 11, and the main shaft 13 is rotated by a servomotor 14. A tailstock 15 is placed on the right end of the table 11, and the tailstock 1 is
A workpiece W composed of a camshaft is held by the center 16 of the shaft 5 and the center 17 of the main shaft 13. Workpiece W
Is fitted to a positioning pin 18 protruding from the spindle 13, and the rotation phase of the workpiece W matches the rotation phase of the spindle 13. A tool base 20 that can move back and forth toward the workpiece W is guided behind the bed 10, and a grindstone wheel G that is rotationally driven by a motor 21 is supported on the tool 20. The tool base 20 is connected to a servo motor 23 via a feed screw (not shown) and is moved forward and backward by the forward and reverse rotation of the servo motor 23. On the other hand, in front of the bed 10, a sizing mechanism 60 for measuring the diameter of the workpiece W is provided so as to be slidable in the U-axis and V-axis directions. The sizing device 61 positions the sizing mechanism 60 in the U and V directions. Further, the sizing mechanism 60 is provided with a pair of contacts 62 whose offset distance can be adjusted. This offset interval is set to the machining size of the workpiece W by the numerical control device 30 via the sizing device 61. When the diameter of the workpiece W is measured, the distance between the contacts 62 changes with the change in the diameter of the workpiece W, and the displacement having the set offset distance as the zero point is output to the sizing device 61 as an electric signal. It The sizing device 61 inputs a detection signal from the numerical control device 30 indicating that the rotation angle phase of the main shaft 13 is in the phase in which the diameter of the base circular bottom portion of the cam is measured by the contactor 62. When input, when the distance between the contacts 62 is equal to the set offset distance, the sizing signal is output to the numerical controller 30. The drive units 40 and 41 receive command pulses from the numerical control device 30 to drive the servomotors 23 and 14 respectively.
Is a circuit for driving. The numerical control device 30 is a device that mainly controls the servomotors 14 and 23 synchronously to control the grinding of the workpiece W. A tape reader 42 for inputting profile data, processing cycle data, etc., a keyboard 43 for inputting control data, etc., and a CRT display device 44 for displaying various information are connected to the numerical controller 30. As shown in FIG. 3, the numerical controller 30 is mainly composed of a main CPU 31 for controlling the grinding machine, a ROM 33 storing a control program, a RAM 32 storing input data and the like, and an input / output interface 34.
On the RAM 32, an NC data area 321 for storing NC data, a profile data area 322 for storing profile data, and a feed mode setting area 3 for mode setting.
23, a workpiece mode setting area 324, and a positioning mode setting area 325 are formed. The numerical controller 30 further includes a drive CPU 36, a RAM 35, and a pulse distribution circuit 37 as a drive system for the servomotors 14 and 23. The RAM 35 is a storage device for inputting the positioning data of the grinding wheel G from the main CPU 31, and the drive CPU 36 performs calculations such as slow-up, slow-down, interpolation of a target point, etc. regarding the feed of the grinding wheel G to determine the positioning data of the interpolation point. The pulse distribution circuit 37 is a device that outputs a cycle, and the pulse distribution circuit 37 is a circuit that outputs a movement command pulse. Next, the operation will be described. NC data including machining cycle data is stored in the RAM 32, and the data structure thereof is shown in FIG. This NC data is decoded by the CPU 31 according to the procedure shown in the flowchart of FIG. Step 100
Then, one block of NC data is read out and the next step 102
It is determined whether or not it is the data end. In case of data end, this program is terminated. If it is not the data end, the process proceeds to step 104 and subsequent steps to determine the code of the instruction word. When it is determined in step 104 that the instruction word is the G code, the CPU processing proceeds to step 106 to determine a more detailed instruction code. In steps 106 to 126, the mode is set according to the instruction code. If it is determined to be G00 code in step 106, a flag is set in the feed mode setting area 323 in step 108 and the feed mode is set to the fast feed mode. Similarly, when it is determined to be the G01 code in step 110, the flag in the feed mode setting area 323 is reset in step 112 and the feed mode is set to the grinding feed mode. If it is determined to be G13 code in step 120, a flag is set in the positioning mode setting area 325 in step 122 and the positioning mode is set to the external positioning mode. Similarly, when it is judged to be the G51 code in step 124, a flag is set in the work mode setting area 324 and the work mode is set to the cam mode in step 126. When the above mode setting is completed, the processing of the CPU proceeds to step 130, and the processing according to the set mode is performed. When it is determined in step 130 that there is an X code in the read block, the process proceeds to step 132, and it is determined whether the mode setting is cam mode and grinding feed mode (hereinafter referred to as "cam / grinding mode"). When the cam / grinding mode is selected, the positioning mode is determined in step 134. When the external positioning mode is determined by the sizing device, the grinding is terminated when the sizing signal is detected in step 136. Pulse distribution for creation is performed. On the other hand, when the external positioning mode is not set, pulse distribution is performed for creating a cam for performing a constant cut. On the other hand, when it is determined in step 132 that the cam / grinding mode is not in effect, pulse distribution is performed in step 140 that is not synchronized with normal rotation of the spindle. In the NC data shown in FIG. 4, the grinding wheel G is fast-forwarded to the position X25.0 by the G00 code of the block N010, the workpiece mode is set to the cam mode by the G51 code of the next block N020, and the profile is set. The data is specified by the number P2345. The feed mode is set to the grinding feed mode by the G01 code of the next block N030.
3 The code sets the positioning mode to the external positioning mode. Also, due to the presence of X code, the maximum is
The cam grinding process is performed up to the position. F code is the spindle
The grinding amount per one rotation, and the R code represents the grinding speed with respect to the rotation of the spindle. Therefore, F0.25 R0.25
If you specify (this R code can be omitted), as shown in Fig. 7, the grinding wheel G will be ground at a speed of 0.25 mm / spindle rotation and up to 2.5 mm if a sizing signal is not detected. . The creation of a cam that completes the cutting by the sizing signal is executed according to the flowchart of FIG. The profile data is stored in the RAM 32, and the amount of movement of the grinding wheel G for each rotation angle of the main shaft of 0.5 ° is given by the number of pulses. First, in step 200, the cutting amount per unit rotation angle of 0.5 ° of the spindle is calculated as the number of pulses from the given R code. Then, the positioning data (movement amount and speed) of the grinding wheel G for each unit rotation angle of the main shaft is output to the RAM 35 for passing to the drive CPU 36 by the processing in and after step 202. When the main CPU 31 receives the pulse distribution completion signal from the drive CPU 36, it outputs the next positioning data. The positioning data is generated and output as follows.
When it is determined that the pulse distribution is completed in step 202,
The process proceeds to step 204, and it is determined whether it is the end of the profile data. If it is not the end, the next profile data, that is, the amount of movement per rotation angle is read in step 206, and it is determined in step 208 whether a sizing signal has been input from the sizing device. When the sizing signal is not detected, the amount of cut per unit angle is added to the read profile data to generate movement amount data, and in step 214, positioning is performed by combining the movement amount data and speed data. The data is output. On the other hand, when it is determined in step 208 that the sizing signal is detected, in step 212, the read profile data is directly used as the movement amount data. Further, when it is determined in step 204 that the profile data is the end, that is, when the spindle has rotated once and returned to the initial phase, the process proceeds to step 216, and it is determined whether or not the sizing signal is detected as in step 208. If the size signal is not detected, the process proceeds to step 218, and the position for reading the profile data is initialized to the beginning of the data in order to generate the positioning data for the next official creation. Then, the feed control in the next spindle rotation cycle is performed by the same processing as described above. On the other hand, if the sizing signal is detected, block N0
The cam grinding process instructed in 30 is completed. Referring to FIG. 7, when the spindle is rotated, profile is created and cutting is performed at a speed of 0.25 mm / spindle rotation, and when the sizing signal is detected at the grinding position of q2 point, the cutting is stopped and then initial It can be seen that only profile creation is done up to q3 points of phase. The profile creation and incision between q1 and q2 is executed during the control cycle through step 210, and the profile creation between q2 and q3 is performed by step.
Executed during a control cycle through 212. The point q3 corresponds to the control cycle of step 220.

【The invention's effect】

The present invention combines the profile data and the cut data, and in the grinding step of performing the cut by superimposing it on the profile creation motion, when the machining dimension is measured and the sizing signal is detected, immediately stop only the cut. Since the profile creation movement is continued, the processing accuracy in constant-dimension grinding is improved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the concept of a tool feeding operation during constant-size grinding by the device of the present invention, FIG. 2 is a block diagram of a numerical control grinding machine according to an embodiment of the present invention, and FIG. 3 is a numerical control. Block diagram showing the electrical configuration of the device, Fig. 4 is NC
FIG. 5 is a flow chart showing the processing procedure of the CPU, and FIG. 7 is an explanatory diagram showing the cutting and stopping operation of the grinding wheel. 10 ... Bed, 11 ... Table, 13 ... Spindle, 1
4, 23 ... Servo motor, 15 ... Tailstock, 20 ...
Tool stand, 30 ... Numerical control device, 60 ... Sizing mechanism, 6
1 ... Sizing device, 62 ... Contact, G ... Tool (grinding wheel), W ... Workpiece

Claims (1)

[Claims] 1. Profile data for numerically controlling a tool feed axis with respect to the rotation of a spindle to cause a tool to generate a profile along a finish shape of a non-round work piece, and fast feed, cut, fast feed backward, etc. of the tool. In a numerically controlled grinding machine for machining the non-round workpiece, based on the machining cycle data for controlling the machining cycle, the machining dimension is measured during machining of the non-round workpiece, and the machining dimension has a predetermined value. Sizing device that outputs a sizing signal when reaching, the data setting means that gives the cutting data for controlling the cutting operation of the tool to the rotation of the spindle, and the cutting data is superimposed on the profile data. Grinding means for cutting along with the profile generating motion in synchronization with the rotation of the spindle, and when the sizing signal is input from the sizing device, the cutting data And a cutting stop means for stopping the cutting of the tool to stop the cutting of the tool and performing only the profile creation motion.