JPS6384864A - Numerically controlled grinding machine - Google Patents

Abstract

PURPOSE:To improve machining accuracy in the fixed size grinding, by equipping a grinding machine with a grinding means, which cuts a work with its profile generating motion synchronously with the rotation of a main spindle, and a cut stopping means which stops cutting by a tool only performing the profile generating motion to the initial phase when a fixed size signal is input. CONSTITUTION:A tool G performs a reciprocating motion in a direction X synchronously with the rotation in a direction theta of a main spindle, but the tool G, if it is viewed from a coordinate system fixed to a work W, performs a peripheral motion around the work W in the direction of an arrow head A in the drawing. Here a profile generating motion and cutting action, synchronized with the rotation of the main spindle, are simultaneously executed. That is, a grinding means grinds the work W controlling a position of the tool G along a spirally curved line M for a curved line L. And a cut stopping means, if a fixed size signal is output from a fixed size device in a point P2 during grinding, causes the toll G to stop its cutting and to perform the profile generating motion along a curved line Lp to a position Pe corresponding to the initial phase.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a numerically controlled grinding machine for grinding non-perfect circular workpieces (hereinafter also simply referred to as "workpieces") such as cams.

[Prior art]

Conventionally, a method is known in which a numerical control device controls the feed of a grinding wheel in a direction perpendicular to the spindle axis in synchronization with the rotation of the spindle to grind a workpiece such as a cam. In order to synchronously control the feed of the grinding wheel, it is necessary to provide profile data to the numerical control device. 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 is reciprocated along the finished shape of the workpiece, that is, it is moved to create a profile. On the other hand, in order to grind a workpiece, in addition to profile data, machining cycle data for controlling machining cycles such as feeding, cutting, and retracting of the grinding wheel is required. The workpiece is machined based on this machining cycle data and profile data, and especially in the case of sizing grinding, the relationship between the cutting motion and the profile creation motion is important in terms of machining accuracy and machining speed.

[Problems to be solved by the invention]

Conventional grinding machines have a function that superimposes the cutting operation of a tool in synchronization with the rotation of the spindle on the profile creation movement. In this case, the control unit is one cycle of the profile creation movement, that is, one rotation of the spindle, so even if the sizing signal is detected, cutting cannot be stopped until the current control cycle is completed. For this reason, there was a problem of cutting too much. The present invention has been made to solve the above-mentioned problem, and its purpose is to improve machining accuracy in sizing grinding of non-perfectly circular workpieces.

[Means to solve the problem]

The configuration of the invention for solving the above problems is such that in a numerically controlled grinding machine that processes a non-perfectly circular workpiece based on profile data and machining cycle data, the machined dimensions of the non-perfectly circular workpiece reach a predetermined value. a sizing device that outputs a sizing signal when the tool is cut, a data setting device that provides cutting data that controls the cutting operation of the tool, and creating a profile in synchronization with the rotation of the spindle based on the profile data and the cutting data. A grinding means that cuts with movement;
When the sizing signal is input from the sizing device, the cutter stops cutting of the tool and performs only the profile creation movement up to the initial phase.

[Effect]

FIG. 1 shows the locus of movement of the tool relative 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 spindle in the θ direction, but when viewed from the coordinate system fixed to the workpiece W, the tool G revolves around the workpiece W in the direction of the arrow. It becomes a movement. L is the locus of the center of the tool G when the tool G performs only a profile generating motion with respect to the workpiece W. In the above-mentioned grinding machine, a profile creation motion and a cutting motion synchronized with the rotation of the main shaft are simultaneously executed. That is,
The grinding means controls the position of the tool G along the spiral curve M to grind the workpiece W. And while grinding,
When the sizing signal is output from the sizing device at point 22, the cutting stop means stops the cutting of the tool and moves the tool along the white line Lp to a position Pe corresponding to the initial phase to create a profile. . In this way, as soon as the sizing signal is detected, only the cutting of the tool is stopped. Furthermore, upon completion of the operation of the cutting stop means, the tool is set to the initial phase of the profile generating movement.

【Example】

The present invention will be described below based on specific examples. FIG. 2 is a configuration diagram showing a numerically controlled grinding machine. 10 is a bed of a numerically controlled grinding machine, and a table 11 is slidably disposed on this bed 10. A headstock 12 having a main spindle 13 mounted thereon is disposed on the table 11, and the main spindle 13 is rotated by a servo motor 14. Further, a tailstock 15 is placed on the right end of the table 11.
A workpiece W consisting of a camshaft is held between the center 16 of No. 5 and the center 17 of the main shaft 13. Workpiece W
is fitted into a positioning pin 18 protruding from the main shaft 13, and the rotational phase of the workpiece W matches the rotational phase of the main shaft 13. A tool stand 20 that can move forward and backward toward the workpiece W is guided behind the bed 10, and a grinding wheel G that is rotationally driven by a motor 21 is supported on the tool stand 20. This tool stand 20 is connected to a servo motor 23 via a feed screw of the circuit.
The servo motor 23 is connected to and moved forward and backward by forward and reverse rotation of the servo motor 23. On the other hand, a sizing mechanism 60 for measuring the diameter of the workpiece W is disposed in front of the bed 10 so as to be slidable in the U-axis and V-axis directions. Positioning of the sizing mechanism 60 in the USv axis direction is performed by a sizing device 61. 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 dimensions of the workpiece W by the numerical control device 30 via the sizing device 61. When measuring the diameter of the workpiece W, the interval between the contacts 62 changes as the diameter of the workpiece W changes, and the displacement with the set offset interval as the zero point is output to the sizing device 61 as an electrical signal. Ru. The sizing device 61 inputs a detection signal from the numerical control device 30 indicating that the rotational angle phase of the main shaft 13 is in the phase in which the diameter of the base round bottom of the cam is measured by the contactor 62. When input, if the spacing between the contacts 62 is equal to the set offset spacing, a sizing signal is sent to the numerical control device 3.
Output to 0. Drive units 40 and 41 input command pulses from numerical controller 30 and drive servo motors 23 and 14, respectively.
This is the circuit that drives the . The numerical control device 30 is a device that mainly synchronously controls the servo motors 14 and 23 to control the grinding process of the workpiece W. Connected to the numerical control device 30 are a tape reader 42 for inputting profile data, machining cycle data, etc., a keyboard 43 for inputting control data, etc., and a CRT display device 4.4 for displaying various information. As shown in FIG. 3, the numerical control device 30 mainly includes a main CPU 31 for controlling the grinding machine, a ROM 33 that stores a control program, a RAM 32 that stores input data, etc., and an input/output interface 34. The RAM 32 has 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 control device 30 is also provided with a drive CPU 36, a RAM 35, and a pulse distribution circuit 37 as a drive system for the servo motors 14 and 23. The RAM 35 is a storage device that inputs the positioning data of the grinding wheel G from the main CPU 31, and the drive CPU 36 inputs the positioning data of the grinding wheel G.
It is a device that performs calculations such as slowdown and interpolation of target points and outputs positioning data of interpolated points at regular intervals, and the pulse distribution circuit 37 is a circuit that outputs movement command pulses. Next, the effect will be explained. NC data including machining cycle data is stored in the RAM 32, and the data structure is shown in FIG. This NC data is decoded by the CPU 31 according to the procedure shown in the flowchart of FIG. Step 10
0, one block of NC data is read out, and the next step 1 is read out.
At step 02, it is determined whether or not it is the data end. In the case of data end, this program is terminated. If it is not the data end, the process moves to step 104 and subsequent steps, and the code of the instruction word is determined. In step 104, the instruction word is G.
If it is determined that the instruction code is a code, the CPU process proceeds to step 106 in order to determine a more detailed instruction code.
Move to. In steps 106 to 126, mode setting is performed according to the instruction code. When it is determined in step 106 that the code is a GOO code, a flag is set in the feed mode setting area 323 in step 108, and the feed mode is set to fast forward mode. Similarly, when it is determined in step 110 that it is a GOI code,
At step 112, the flag in the feed mode setting area 323 is reset and the feed mode is set to the grinding feed mode. Further, when it is determined in step 120 that the code is G13, in step 122 the positioning mode setting area 325 is
A flag is set and the positioning mode is set to external positioning mode. Similarly, when it is determined in step 124 that the code is 051, a flag is set in the workpiece mode setting area 324 in step 126, and the workpiece mode is set to cam mode. When the above-mentioned mode setting is completed, the processing of the CPU moves to step 130, and processing according to the set above-mentioned mode is performed. If it is determined in step 130 that there is an X code in the read block, the process moves 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"). cam·
When in the grinding mode, the positioning mode is determined in step 134, and when it is determined that the mode is an external positioning mode in which positioning is performed by the sizing device, in step 136, a cam creation mode is executed to finish grinding when the sizing signal is detected. Pulse distribution is performed for this purpose. On the other hand, when not in the external positioning mode, pulse distribution is performed to generate a cam that performs a fixed amount of cutting. On the other hand, if it is determined in step 132 that the mode is not the cam/grinding mode, then in step 140 pulse distribution that is not synchronized with the normal rotation of the main shaft is performed. In the NG data shown in FIG. 4, GO of block N010
O code causes grinding wheel G to move to position X25. The workpiece mode is set to cam mode by the G51 code of the next block NO2O, and the profile data is specified by the number P2345. The feed mode is set to the grinding feed mode by the GOI code of the next block No. 30, and the positioning mode is set to the external positioning mode by the G13 code. Also, X
Due to the presence of the cord, cam grinding is performed up to the maximum position of X22.5. The F code represents the amount of grinding per rotation of the spindle, and the R code represents the grinding speed relative to the rotation of the spindle. Therefore, if you specify Fo, 2S Ro, 25 (this R code can be omitted), the grinding wheel G will grind at a speed of 0.25 m1n/spindle rotation and the sizing signal will be detected, as shown in Figure 7. If not, it will be ground by a maximum of 2.5mm. The cam creation that completes the cut in response to the sizing signal is executed according to the flowchart in FIG. The profile data is stored in the RAM 32, and the amount of movement of the grinding wheel G for every 0.5° of rotation angle of the main shaft is given in the number of pulses. First, in step 200, the depth of cut for each unit rotation angle of 0.5 degrees of the spindle is calculated as the number of pulses from the given R code. Then, through the processing in step 202 and subsequent steps, the positioning data (travel amount and speed) of the grinding wheel G for each unit rotation angle of the main spindle is stored in the RAM 3 in order to be passed to the drive CPU 36.
5 is output. Main CPU31 is drive CPU3
When the pulse distribution completion signal is input from 6, the next positioning data is output. Positioning data is generated and output as follows. When it is determined in step 202 that the pulse distribution is completed, the process moves to step 204, and it is determined whether or not the end of the profile data has been reached. If it is not the end, step 206
At step 208, the next profile data, that is, the amount of movement of the rotating breast contact, is read out, and at step 208, it is determined whether or not a sizing signal has been input from the sizing device. When the sizing signal is not detected, the cutting amount per unit angle of light is added to the read profile data to generate movement amount data, and in step 214, the movement amount data and speed data are combined. Positioning data is output. On the other hand, when it is determined in step 208 that the fixed size signal has been 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 at the end, that is, when the main shaft has made one revolution and returned to the initial phase, the process moves to step 216 and step 208
Similarly, it is determined whether or not a sizing signal is detected, and if a sizing signal is not detected, the process moves to step 218 to generate positioning data for the next generation process, so that the reading position of the profile data is the same as the data. It is initialized at the beginning of. Then, feed control in the next spindle rotation cycle is performed by the same process as above. On the other hand, if the sizing signal is detected, block N
The cam grinding process commanded at O30 is completed. Referring to FIG. 7, profile creation and cutting are performed at a speed of 0.25 mm/spindle rotation as the spindle rotates.
It can be seen that when the sizing signal is detected at the grinding position of 92 points, the cutting is stopped, and then only profile creation is performed up to the initial phase of 13 points. Profile creation and cutting between ql and q2 are performed during the control cycle passing through step 210, and profile creation between 92 and 93 is performed during the control cycle passing through step 212. Further, 13 points correspond to the control cycle of step 220.

Effects of the Invention The present invention combines profile data and cutting data, and when a sizing signal is detected in the grinding process in which the cutting is performed superimposed on the profile creation movement, only the cutting is stopped immediately and the cutting is performed. Since the motion is continued until the initial phase, the machining accuracy in sizing grinding is improved and it becomes easier to start the next process.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the concept of tool feeding operation during fixed size grinding by the device of the present invention, Fig. 2 is a block diagram of a numerically controlled grinding machine according to an embodiment of the present invention, and Fig. 3 is a numerically controlled grinding machine. A block diagram showing the electrical configuration of the device, Figure 4 is an NC
The data configuration diagram, FIGS. 5 and 6 are flowcharts showing the processing procedure of the CPU, respectively, and FIG. 7 is an explanatory diagram showing the cutting and stopping operations of the grinding wheel. 10-Bed 11-Table 13-Spindle 14.23
...Servo motor 15-Psychological stand 20°...Tool stand 30...Numerical control device 60゛...Sizing mechanism 6
1...Sizing device 62...Contactor G-Tool (grinding wheel) W-...Workpiece patent applicant Toyota Machinery Co., Ltd. Law

Claims (1)

[Claims] (1) Based on the profile data for moving the tool to create a profile along the finished shape of the non-circular workpiece, and the machining cycle data for controlling the machining cycles such as rapid feed, cutting, and rapid retraction of the tool, A numerically controlled grinding machine that processes a circular workpiece includes a sizing device that outputs a sizing signal when the machining dimension of the non-perfect circular workpiece reaches a predetermined value, and a notch that controls the cutting operation of the tool. data setting means for providing data, based on the profile data and the incision data,
a grinding means that performs a cut along with a profile generation movement in synchronization with the rotation of the spindle; and a cutting stop means that, when the sizing signal is inputted from the sizing device, stops the cutting of the tool and performs only the profile generation movement up to an initial phase. A numerically controlled grinding machine characterized by being equipped with.