JPH0155940B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic measurement correction device for a numerically controlled machine tool.

Conventionally, various devices for measuring the machining diameter of a workpiece have been proposed as automatic measurement and correction devices, and the present applicant also filed Patent Application No. 071633 in 1971 (Japanese Patent Application Laid-Open No. 1983-1983).
163286), we proposed a new automatic measurement correction device. This device includes a reference gauge installed concentrically with the workpiece to be machined, a contact detector that emits a signal the moment the stylus contacts the workpiece, and an absolute value method for numerical control. The desired purpose was obtained by organically combining the output of the absolute value detector, which is a characteristic feature. For explaining the present invention, the above-mentioned prior art will be described.

FIG. 1 is a block diagram of one conventional embodiment, which will be explained. 1 is an input tape, 2 is a decoder for decoding the contents of the input tape, and 3 is a command value register for storing the command value decoded by the decoder. Reference numeral 4 denotes a function generator that generates instantaneous command values based on the output values of the command value register. Reference numeral 5 denotes a comparator that compares and subtracts the output value of the absolute value detector output correction means 14 described later and the output value of the tool wear correction means 18 described later from the instantaneous command value which is the output value of the function generator. is for comparing and subtracting the current position, which is the output of the absolute value detector 9, which will be described later. Reference numeral 6 denotes a DA converter that converts the digital quantity output from the comparator 5 into an analog quantity. 7 is a servo amplifier for amplifying the output of the D-A converter 6, and 8 is a servo motor for moving the traversing table. Reference numeral 9 denotes an absolute value detector for detecting the current position of the traversing table. 10 is an AND gate that passes the output value of the absolute value detector 9 at the timing of a contact signal TS1 generated when a contact detector 23 is brought into contact with a reference gauge, which will be described later, and 11 is an output that has passed through the AND gate. This is a register that stores values. 12 is a subtracter that subtracts and outputs the difference between the reference gauge dimension and the register output value. Reference numeral 13 denotes an adder that adds the output value of the subtracter to the output value of the absolute value detector 9. The above AND gate 10, register 11,
The subtracter 12 and the adder 13 constitute an absolute value detector output correction means 14. 15 is a contact signal generated when a contact detector 23 (described later) is brought into contact with a workpiece;
This is an AND gate that allows the output value of the absolute value detector output correction means 14 to pass through at the timing of TS2, and 16 is a register that stores the output value that has passed through the AND gate. 17 is a subtracter that subtracts and outputs the difference between the register output value and the workpiece target dimension. Tool wear correction means 1 using the above AND gate 15, register 16, and subtracter 17
8.

FIG. 2 is an explanatory diagram of the operation when performing measurement using the apparatus of the embodiment shown in FIG. 23 in the figure
2 is a contact detector main body, and 24 is a stylus. dashed line
P ₀ , P ₁ , P ₂ , P ₃ , P ₄ , P ₅ , P ₆ , and P ₇ indicate the locus taken by the tip of the stylus 24 according to the measurement program. The reference gauge 27 and the workpiece 28 are attached with the spindle center line 29 as the axis.
The contact detector 23 is arranged so that its outer diameter is brought into contact with the stylus 24 of the contact detector 23. Note that TS1 shown in FIG. 1 is a contact signal generated at point P2 when the stylus 24 is brought into contact with the reference gauge 27 according to a program, and TS2 is a contact signal generated at point _P2 when the stylus 24 is brought into contact with the reference gauge 27 according to a program.
This is the contact signal that is emitted at _{the 6} points P when touched.

Figure 3 shows the outline of the main body of the machine.
The same numbers as in the figures and FIG. 2 indicate the same parts. In the figure, when the servo motor 8 rotates, the feed screw 21 drives the transverse feed table 22. 25 is the tool rest,
Reference numeral 26 denotes a tool cutting edge, and the cutting edge 26 is arranged at approximately the same position as the tip of the stylus 24. Further, Japanese Patent Publication No. 11670/1984 is known as a device for measuring a reference gauge and a point on the diameter of a workpiece as shown in FIG.

In the prior art described above, it is assumed that the dimensions of the reference gauge itself have a constant value. However, when the temperature of the spindle increases, the dimensions of the reference gauge itself change, making it impossible to accurately determine the thermal displacement at the center of the spindle, making it difficult to accurately measure the dimensions of the workpiece. . Moreover, Jikoko 54-
A method such as No. 10618 that measures two points on the diameter of the workpiece is known, but it has the disadvantage that measurement cannot be performed on objects where the detector cannot be brought into contact with two points on the diameter of the workpiece.

The present invention provides an automatic measurement and correction device that can accurately determine the amount of thermal displacement of the spindle axis even if a dimensional change occurs in the reference gauge itself.

FIG. 4 is a block diagram of one embodiment of the present invention, which will be described. Elements with the same numbers as in FIG. 1 indicate the same elements, and therefore their explanations will be omitted. 31 is an AND gate that allows the output value a of the absolute value detector 9 to pass through at the timing of the contact signal TS1A that is generated when the contact detector 23 is brought into contact with one point facing the reference gauge; 32 is the AND gate; This is a register that stores the output value a that has passed through. 33 is a contact signal generated when the contact detector 23 is brought into contact with another opposite point of the reference gauge;
It is an AND gate that passes the output value b of the absolute value detector 9 at the timing of TS1B, and is 34
is a register that stores the output value b that has passed through the AND gate 33. 35 is the thermal displacement C= of the spindle center due to thermal influence based on the output value b of the register 34 and the output value a of the register 32.
This is an arithmetic unit that calculates -ba/2. Reference numeral 36 denotes an adder for adding the thermal displacement of the spindle axis, which is the output value of the calculator 35, to the output value of the absolute value detector 9. The above AND gate 31, register 32,
AND gate 33, register 34, arithmetic unit 35,
The adder 36 constitutes an absolute value detector output correction means 37 which is a feature of the present invention.

FIG. 5 is an explanatory diagram of the operation when performing measurement using the apparatus of the embodiment shown in FIG. 23 in the figure
2 is a contact detector main body, and 24 is a stylus. dashed line
P ₀ , P ₁ , P ₂ , P ₃ , P ₄ , P ₅ , P ₆ , P ₇ , P ₈ , P ₉ ,
P ₁₀ and P ₁₁ indicate trajectories taken by the tip of the stylus 24 according to the measurement program. However, when inserting the workpiece 28 shown by the two-dot chain line into the chuck 41, the stylus 24 is inserted into the chuck 41 as indicated by the broken lines ₀ , ₁ , ₂ , ₃ , ₄ ,
This occurs after the measurement programs for P ₅ , P ₆ , P ₇ , and P ₈ are completed. 42 is an inner diameter reference gauge inserted into the chuck 41, and the reference gauge and the workpiece 28 are attached with the spindle center line 29 as an axis, and the reference gauge is inserted by the stylus 24 of the contact detector 23. The inner diameter of the workpiece and the outer diameter of the workpiece are arranged so that they are in contact with each other. Note that TS1A shown in Figure 4
The stylus 24 is set to the reference gauge 4 by a program.
TS1B is a contact signal that is emitted at ₃ points when the stylus 24 is brought into contact with the reference gauge 42.
This is the contact signal that is emitted at point _P5 when touched.
TS2 is when the stylus 24 is brought into contact with the workpiece 28
P This is a contact signal emitted at ₁₀ points.

Figure 6 shows the outline of the main body of the machine.
The same numbers as in the figures and FIG. 5 indicate the same parts. In the figure, when the servo motor 8 rotates, the feed screw 21 drives the transverse feed table 22. 25 is the tool rest,
Reference numeral 26 denotes a tool cutting edge, and the cutting edge 26 is disposed at approximately the same position as the tip of the stylus 24 in the radial direction of the reference gauge or workpiece.

FIG. 7 is an operational explanatory diagram for explaining the absolute value detector output correction means 37 in the present invention. In the figure, O is the spindle centerline when the thermal displacement of the spindle center is zero, and the absolute value detector 9 is set to output zero when the cutting edge is on the centerline. O' is the spindle center line when the thermal displacement C of the spindle center occurs, and therefore the reference gauge 42
It shows the state in which it coincides with the center line of . a is when the stylus 24 is brought into contact with the reference gauge 42;
This is the output value of the absolute value detector 9 read out at the timing of the contact signal TS1A generated at the _P3 point. b also connects the stylus 24 to the reference gauge 4.
Contact signal generated at point _P5 when touching 2
This is the output value of the absolute value detector 9 read out at the timing of TS1B. The output value a and the output value b have opposite signs, and in the example of this figure, a=
+29.950, b=-30.050 is used. As is clear from the figure, the center position of the new spindle center line is
O'=b+a/2=-0.050, and the thermal displacement of the spindle center is C=-b-a/2=+0.050. These values a and b are stored in the register 32 and register 34 at timings TS1A and TS1B, respectively, and the thermal displacement amount of C=-ba-a/2 is calculated by the arithmetic unit 35. . The thermal displacement C is added to the output value of the absolute value detector 9 by the adder 36.

FIG. 8 is an explanatory diagram of the operation when a dimensional change occurs in the reference gauge 42 itself shown in FIG. 7. FIG. 8 shows a state where a dimensional change of α=0.002 has occurred in the radial direction compared to FIG. 7. a′ is the contact signal TS1A
The absolute value detector 9 read out at the timing of
The output value is a'=a+α=+29.950+0.002.
Similarly, b' is the output value read at the timing of TS1B, which is b'=b-α=-30.050-0.002. Therefore, the main axis center line O' is O'=b'+a'/2=b-α+a+α
/2 =b+a/2=-0.050, and the thermal displacement C of the spindle center is also C=-b'-a'/2=-(b-α)-(a+α)/2
It can be seen that = -b-a/2 = +0.050, which is the same value as in the case of Fig. 7.

As explained above, according to the automatic measurement correction device of the present invention, two points on the inner diameter or outer diameter of the reference gauge are measured, and based on the measured values, the thermal displacement of the new spindle centerline, that is, the spindle center is calculated. Therefore, it is possible to provide an automatic measurement correction device that is not affected by dimensional changes caused by heat in the reference gauge itself. In addition, even if the detector cannot directly touch two points on the inner or outer diameter due to the shape of the workpiece, only one point on the diameter can be measured, making it possible to handle workpieces of various shapes. has. In the description of the present invention, an inner diameter reference gauge is used as the reference gauge, but it is of course possible to use an outer diameter reference gauge.

[Brief explanation of drawings]

Figure 1 is a block diagram of one conventional embodiment, Figure 2 is a block diagram of a conventional embodiment;
The figures are an explanatory diagram of the operation of FIG. 1, FIG. 3 is a diagram schematically showing the conventional machine main body, FIG. 4 is a block diagram of an embodiment of the present invention, and FIG. 5 is an explanatory diagram of the operation of FIG. 4. FIG. 6 is a diagram schematically showing the main body of the machine of the present invention, FIG. 7 is an operational explanatory diagram for explaining the absolute value detector output correction means of the present invention, and FIG. 8 is the reference gauge itself shown in FIG. 7. FIG. 4 is an explanatory diagram of the operation when a dimensional change occurs in the image forming apparatus. 4...Function generator, 5...Comparator, 9...Absolute value detector, 10...And gate, 11...Register, 12...Subtractor, 13...Adder, 14...
... Absolute value detector output correction means, 15 ... AND gate, 16 ... Register, 17 ... Subtractor, 18
...Tool wear correction means, 31...And gate, 32...Register, 33...And gate,
34...Register, 35...Arithmetic unit, 36...Adder, 37...Absolute value detector output correction means, 42
...Reference gauge.

Claims (1)

[Scope of Claims] 1. A function generator that issues instantaneous command values based on tape command information, etc., an absolute value detector for detecting the current position of the carriage, and an absolute value detected from the output of the function generator. an absolute value type numerical control device having a comparator for comparing and subtracting the outputs of the detectors, and controlling the position of the carriage by driving and controlling a servo motor using the output of the comparator, and a numerical control device installed on the carriage; In a machine tool, the contact detector is equipped with a contact detector that emits a contact signal the moment the stylus contacts the workpiece, and a reference gauge that is installed concentrically with the workpiece to be machined. A first AND gate that passes the output of the absolute value detector in response to a contact signal when the reference gauge is brought into contact with a first point facing each other on the diameter of the inner diameter or outer diameter; and an absolute value that passes through the first AND gate. a first register for storing the value detector output; and a second AND gate for passing the absolute value detector output in response to a contact signal when the contact detector is brought into contact with an opposing second point of the reference gauge; a second register that stores the output of the absolute value detector that has passed through the second AND gate; a computing unit that calculates the thermal displacement of the spindle center based on the numerical values stored in the first register and the second register; Absolute value detector output correction means configured with an adder for adding the arithmetic unit output to the absolute value detector output, and the absolute value detector output correction means when the stylus is brought into contact with the workpiece. and a tool wear correction means for reading the output of the output value and calculating the difference between the output value and the target workpiece dimension, and comparing the output of the absolute value detector output correction means and the output of the tool wear correction means. An automatic measurement correction device for a numerically controlled machine tool, characterized in that the device is configured to subtract the output from the function generator at the function generator. 2. The tool wear correction means is configured to pass the output of the absolute value detector output correction means in response to a contact signal when the contact detector is brought into contact with the workpiece.
an AND gate, a third register for storing the output of the absolute value detector output correction means that has passed through the third AND gate, and a subtraction operation for determining the difference between the numerical value stored in the third register and the target workpiece dimension. An automatic measurement correction device for a numerically controlled machine tool according to claim 1, which comprises a device and a device.