JP2003340687A - Intra-machine workpiece measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intra-machine workpiece measuring device which measures the dimension of a workpiece by the use of a touch sensor while avoiding an influence of the thermal displacement of a feed screw. <P>SOLUTION: The intra-machine workpiece measuring device is provided for a numerical control machine tool having a rotary cutter holder which is rotated about a turret rotation shaft to position a working tool to a working location. The intra-machine workpiece measuring device is formed of the touch sensor, an angle detector, and an arithmetic section. The touch sensor is attached to the turret, and has the tip of a measuring element thereof moved along an arcuate track by the rotation of the turret, to thereby detect the contact thereof with a workpiece surface to be measured. The angle detector detects the rotating angle of the turret rotation shaft upon contact with the surface to be measured. The arithmetic section calculates the radial direction of the workpiece from a center distance between the turret and the workpiece and the measured rotation angle. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention [Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-machine work measuring device for measuring the size of a work in the machine during or after the machining of the work.

[Prior art]

FIG. 7 shows an in-machine work measuring device for a lathe, in which a touch sensor is attached to a tool post.
When the scissors gauge is attached to the turret,
It is a touch sensor that measures the outer shape of the work. In FIG. 7, the touch sensor 101 is attached to the tool attachment portion of the turret 102 in place of a tool. Workpiece 103 is spindle 1
It is gripped by the claw 106 of the chuck 105 which is fixedly attached to 04. The inner diameter 103a of the work 103 is measured by sending the touch sensor 101, which is attached to the turret 102 in place of a tool, in the X-axis direction of the tool rest and positioned.

In FIG. 8, the scissors gauge 107 is attached to the tool attachment portion of the turret 102 in place of a tool. When measuring the work 103, the turret 102 is X
The measurement is performed by being positioned in the axial direction. The gauge between the sensors of the scissors gauge is adjusted each time according to the size of the work 103. In FIG. 9, a work 103 of a shaft to be turned is sandwiched between a main shaft 105 and a rotation center 109. This is performed by the touch sensor 101 provided on the turret 102.

[0004]

As described in the prior art, in the measurement example shown in FIG.
When the touch sensor 101 is brought into contact with two inner diameter surfaces on a plane passing through the central axis of 03, and the diameter is measured, an unnecessary stroke in the negative direction of the X axis is required for turning the turret 102 of the tool post. Therefore, there is a problem that it is generally not suitable for measuring a large diameter.

In the measurement example shown in FIG. 8, the workpiece 1 to be measured is
Since it is necessary to adjust the gauge width according to the diameter of 03, there is a limit to the work diameter that can be measured, which causes a problem in versatility. In the measurement example in the shaft work machining using the tailstock shown in FIG. 9, since the radius measurement is performed, the measurement result includes the deviation between the origin of the X axis and the center of the spindle, which causes a problem that the measurement accuracy is deteriorated.

The present invention has been made in view of the above problems of the prior art, and its object is to:
Since the touch sensor touches the workpiece by the turning of the turret turning axis instead of positioning by the X-axis control of the turret, an angle detector that detects the angle at the time of contact and a calculation that calculates the diameter dimension from the detected turning angle It is intended to provide an in-machine work measuring device having a section.

[0007]

In order to achieve the above object, the invention of claim 1 is such that a turret on which a machining tool is mounted pivots about a turret pivot axis to index the machining tool to a machining position, and the turret. An in-machine work measuring device for a numerically controlled machine tool having a swivel tool post capable of moving and positioning in the X-axis direction, which is a direction approaching and separating from a work on a plane parallel to a swivel plane, wherein A touch sensor whose tip moves along an arcuate locus by the turning of the turret to detect contact with the measurement surface of the workpiece, an angle detector which detects the turning angle of the turret turning axis when the contact is made, the turret and the A calculation unit that calculates the radial dimension of the work by a calculation formula that includes the center distance to the work and the measured turning angle is provided. And it calculates the radial dimension of the workpiece and knowledge.

According to the first aspect of the present invention, a touch sensor is fixed to the turret to detect the contact with the work by the turret rotation operation, and the turret rotation angle at the time of detecting the detection signal of the touch sensor is detected. The work size is calculated from the previously known distance from the turret rotation axis center to the touch sensor and the detected angle. The angle is detected by a detector attached to the turret rotation motor shaft. Therefore, since the work and the touch sensor are brought into contact with each other by the turret rotation, it is possible to measure the work from a small diameter to a large diameter. Either the inner diameter or the outer diameter can be measured only by the swiveling motion of the contact point, and there is no need to adjust the gauge even if the work size changes like a scissor gauge.

According to a second aspect of the present invention, in the plane including the arcuate locus, the center distance is set so as to bring the probe into contact with the outer diameter portion of the workpiece substantially parallel to the moving direction of the turning tool rest. The influence of the thermal displacement generated in the numerically controlled machine tool on the measurement is reduced.

According to the second aspect of the present invention, when the contact point of the touch sensor draws an arc-shaped locus and contacts the surface from the outside of the work, the arc-shaped locus has the same diameter of the planned work diameter. By making the diameter line and the X-axis substantially orthogonal to each other so as to pass two points on the line, the influence of thermal displacement of the ball screw shaft for positioning the X-axis is minimized.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 is a configuration explanatory view of an in-machine work measuring device of the present invention, FIG. 2 is a measurement state diagram of a touch sensor by turning of a turret, FIG. 3 is a relational position diagram when a probe center locus of the touch sensor passes through the work center, FIG. 4 is a relational position diagram in the case where the probe center locus of the touch sensor is offset from the work center.

In FIG. 1, a touch sensor 2 having a probe 1 that contacts the work W as a constituent element is provided on the outer peripheral surface 3a or the end surface 3b of the turret 3. Turret 3
Rotates integrally with the turret rotation shaft 4 supported by a tool rest (not shown) whose position is controlled in the X-axis direction. The turret 3 is indexed and driven by a turning motor 7 via a pair of large gears 5, a small gear 6, and other conductive members.

Since the turret 3 enables swivel positioning, the backlash of the transmission gear portion must be close to zero. As a usual means, it is conceivable to use a method in which one of a pair of gears is used as a superposed gear to form a tooth profile, and when the tooth profile is engaged with the other, the tooth profile is shifted to eliminate backlash and then fixed. The turning motor 7 usually has an angle detector 8
Has been attached. It is possible to provide an angle detector 9 at the shaft end of the turret rotation shaft 4 in order to improve the detection accuracy of the rotation angle of the turret 3.

In FIG. 2, the turret 3 is a turret swivel.
Axis 4 axis O₁And workpiece W axis O _WPosition on the line connecting
It is decided and controlled (X axis). Therefore, the touch sensor 2
The work piece W is measured by the measuring element 1 of the turret 3 on the X-axis.
Is moved back and forth in the same direction for positioning, and then the contact point 1 is the work piece.
The angle when moving from the outside of W and touching the work is that
Each θ₁And θ₂This turning angle is detected by the angle detector 8 or
Is detected at 9.

When the shapes of the touch sensor 2 and the turret 3 are determined, the center distance line segment O ₁ O _W between the turret 3 and the workpiece W when measuring the workpiece W can be determined. As one of the determination methods, the center distance line segment O ₁ O _W is determined so that the arcuate locus drawn by the center of the tracing stylus 1 by the turret rotation passes through the axis O _W of the work W. The axis O ₁ of the turret turning shaft 4 is controlled by X-axis positioning, and the turning angles θ ₁ and θ ₂ are directly connected to the angle detector 8 integrally attached to the turning motor 7 or the turret turning shaft 4. The angle is measured by the angle detector 9. The measured turning angles θ ₁ and θ ₂ are the geometrical dimension calculation unit 1
The dimension of the workpiece W is calculated based on the programmed arithmetic expression input to 0 and output.

Next, a mode of measurement by the in-machine work measuring device according to the present invention will be described. Fig. 3 shows the work center O
_This is the case where the line segment O _W O ₁ = L = R between _W and the turret center O ₁ is set. The machining data is added to the machining program so that the planned machining diameter is the line segment O _W P _0, and the workpiece WP
₀ was to be completed. However, the work W of the processing result
The radius of the machining result of P ₁ was machined by the line segment O _W P ₁ . The contact point 1 of the touch sensor 2 has a contact point P ₁ and a turning angle θP ₁
Was detected. In this case, the radial line segment O _W P of the work WP _1
1 can be calculated from the detected turning angle θP ₁ by the following formula (1).

FIG. 4 shows a case in which a line segment O _W O ₁ is set so that the measuring element comes into contact with the outer diameter portion of the workpiece substantially parallel to the moving direction of the tool rest. Since it is offset by S with respect to FIG. 3, the line segment O _W O ₁ = L = R
-S. The planned machining diameter is the line segment O _{W in the} machining program.
The work WQ ₀ was scheduled to be completed by adding the machining data so as to be Q ₀ . However, the work result WQ
_{In No. 1,} the radius of the processing result was processed by the line segment O _W θ ₁ . The contact point 1 of the touch sensor 2 did not detect the turning angle θQ ₀ at the contact point Q ₀ , but detected the turning angle θQ ₁ at the point Q ₁ . In this case, the radial line segment O _W Q ₁ of the work WQ ₁ is the detected turning angle θQ ₁
Can be calculated from the following formula (3). The processing error can be obtained by obtaining the difference between the calculated line segment O _W P ₁ or the line segment O _W Q ₁ and the planned machining diameter.

In the actual machining, the center of the work W and the sag
Distance O between the turning centers_WO₁Heat generated during processing
Measurement error due to the thermal displacement of the machine caused by
To do. About the measurement method that reduces the effect of this measurement error
Describe. FIG. 5 shows a case where thermal displacement occurs in the measurement mode of FIG.
The arc-shaped trajectory T1 before thermal displacement is
Center O_WAlthough passing through, due to thermal displacement,
Center O₂Is the turning center O ₁From the thermal displacement X
It FIG. 6 shows that the arc-shaped trajectory T1 before thermal displacement is the planned machining diameter.
Vertex Q₀Although it passes through the center of the work_WDo not pass.
Center O of arcuate locus T2 due to thermal displacement₂Is the turning center O₁
From the thermal displacement amount X.

The measurement point after thermal displacement in FIGS. 5 and 6 is P
₃ and Q ₃ . P ₃ is clear that the angular P ₁ P ₃ Px> corners Q ₁ Q ₃ Qx since away more than the Y-axis than Q _3, the angle _{P 1 P 3 Px = α 1} , the angle angle Q ₁
If Q ₃ Qx = α ₂ , then PxP ₃ = QxQ ₃ = X, and therefore the measurement error in FIG. 5 is the line segment P ₁ Px≈X.
α ₁ , the measurement error in FIG. 6 is the line segment Q ₁ Qx≈Xα ₂ . Comparing the measurement error, Therefore, if the measurement is performed in the state shown in FIG.
It can be seen that even if the above occurs, the influence on the measurement error is small. Such measurement is possible by rotating the touch sensor 2 and measuring between two points close to the diameter dimension, that is, near the apex of the work.

As described above, in the plane including the arcuate locus, the center distance between the work center and the turret rotation axis is determined so that the probe contacts the outer diameter portion of the work substantially parallel to the moving direction of the turning tool rest. It becomes possible by measuring it. It is conceivable that the cause of the change in the center distance L as described above is expansion and contraction in association with the heat generated by the ball screw shaft that drives and positions the turning tool rest in the X-axis direction. Therefore, it is desirable to reduce the influence of the thermal displacement of the ball screw shaft on the measurement result by the probe 1.

[0021]

Since the in-machine work measuring device of the present invention is configured as described above, it has the following effects. According to the first aspect of the present invention, the touch sensor is brought into contact with the workpiece not on the X-axis but on the trajectory of the tracing stylus by the turret rotation. Have. In addition, the diameter of the shaft work can be measured with high accuracy. Further, unlike the scissor gauge, there is an effect that it is not necessary to perform setup change even when the measurement target is changed.

According to the second aspect of the present invention, when the touch sensor is moved straight forward for measurement, a measurement measurement error is included in the thermal displacement, but according to the in-machine work measurement of the present invention in which the touch sensor is swung for measurement. For example, by selecting the center distance between the work and the turret, it is possible to eliminate the measurement error as much as possible in the measurement before and after the thermal displacement.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a configuration of an in-machine work measuring device.

FIG. 2 is a measurement state diagram of a touch sensor by turning a turret.

FIG. 3 is a positional relationship diagram when a trace of the center of the tracing stylus passes through the center of the work (measurement point P ₁ ).

FIG. 4 is a positional relationship diagram in which the trace of the center of the tracing stylus is offset from the center of the work (measurement point Q ₁ ).

FIG. 5 is an explanatory diagram of a contact point when the ball screw shaft has a thermal displacement X when no offset is applied (measurement point P ₃ ).

FIG. 6 is a contact point explanatory diagram when a thermal displacement occurs when an offset S is applied and the contact point Q ₀ is on the Y axis (measurement point Q ₃ ).

FIG. 7 is a schematic diagram of inner diameter measurement by a conventional touch sensor.

FIG. 8 is a schematic diagram of measurement using a conventional scissor gauge.

FIG. 9 is a schematic diagram of outer diameter measurement by a conventional touch sensor.

[Explanation of symbols]

1 Measuring element 2 Touch sensor 3 turret 4 turret rotation axis 5 large gears 6 small gears 7 Turning motor 8 Angle detector 9 Direct connection type angle detector 10 Shape dimension calculator

Continued front page    F term (reference) 3C001 KA01 KA05 TB02                 3C029 BB03 BB04

Claims (2)

[Claims] 1. A X-axis direction which is a direction in which a turret mounted with a machining tool pivots about a turret pivot axis to index the machining tool to a machining position, and moves toward and away from a workpiece on a plane parallel to the turret pivot plane. An in-machine work measuring device for a numerically controlled machine tool having a swivel tool post that can be moved and positioned in the measurement surface of a work piece attached to the turret by moving the arcuate locus by the swiveling of the turret. A touch sensor for detecting the contact of the work piece, an angle detector for detecting the turning angle of the turret turning axis when the contact is made, and a calculation formula including the center distance between the turret and the work piece and the measured turning angle of the work piece. A machine for calculating a radial dimension is provided, and the turning dimension of the touch sensor is detected to calculate the radial dimension of the workpiece. Measuring device. 2. In the plane including the arcuate locus, the center distance is determined so that the probe contacts the outer diameter portion of the workpiece that is substantially parallel to the moving direction of the swivel tool rest, and the numerical value is set. The in-machine work measuring device according to claim 1, wherein the influence of thermal displacement generated in the controlled machine tool on measurement is reduced.