Measuring device and its control method

Abstract

The present invention provides a measuring device and a control method thereof that can minimize damage to the stylus, the workpiece, or both. [Solution] The measuring device includes a vertical moving part 16 that can move in an approach-away direction so that the stylus 22 moves closer to and away from the surface of the workpiece W, and a control device 30 that moves the vertical moving part 16 from a stationary state to the away-away side so that the stylus 22 moves away from the surface of the workpiece W, and then moves the vertical moving part 16 to the approach-away side so that the stylus 22 moves closer to the surface of the workpiece W.

Description

Technical Field

[0001] The present invention relates to a surface shape measuring apparatus and a control method thereof.

Background Art

[0002] There is known a shape measuring apparatus that measures the surface shape such as the surface roughness and contour of a workpiece by moving a detector provided with a stylus along the surface of the measurement object (workpiece) by a drive unit. In such a shape measuring machine, it is required to prevent damage to the stylus, the workpiece, or both, improve the stylus life, and preserve the workpiece.

[0003] For example, in the measuring apparatus of Patent Document 1, the holder of the fine stylus is attached to a fine actuator, and when the fine stylus contacts the measurement object in its axial direction, the stylus is pulled up to escape from the contact so that the fine stylus does not buckle. Further, when there is no risk of buckling, it is not allowed to escape from the contact.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, providing an actuator as shown in Patent Document 1 requires, for example, component arrangements that form a space for the actuator, etc., and is subject to design limitations. Further, the addition of an actuator increases the cost.

[0006] Furthermore, in a shape measuring device, when the drive unit supporting the detector starts moving from a stationary state, it moves rapidly due to the switch from static friction to dynamic friction. At this time, if the stylus is in contact with the workpiece, the energy is transmitted from the tip of the stylus to the workpiece, and the stylus experiences a repulsive force. This repulsive force may cause the stylus to separate from the workpiece, and there is a concern that the stylus may then collide with the workpiece, potentially damaging the stylus, the workpiece, or both.

[0007] The present invention has been made in view of these circumstances, and aims to provide a surface shape measuring device and a control method thereof that can minimize damage to the stylus, the workpiece, or both. [Means for solving the problem]

[0008] The surface shape measuring device of the first embodiment comprises a detector having a stylus that contacts the surface of an object to be measured and a displacement detection unit that detects the displacement of the stylus; a column erected vertically with respect to a base on which the object to be measured is placed; a drive unit provided on the column; a vertical movement unit connected to the drive unit and capable of sliding along the longitudinal direction of the column; a horizontal drive unit supported by the vertical movement unit and capable of moving the detector in a direction perpendicular to the longitudinal direction of the column; a measurement direction information acquisition unit that acquires measurement direction information indicating the measurement direction, which is the direction in which the stylus contacts the object to be measured; a contact information acquisition unit that acquires contact information indicating whether or not the stylus is in contact with the object to be measured; and a movement control unit that, upon receiving a movement instruction for the vertical movement unit, controls the movement of the vertical movement unit based on the movement instruction. The movement control unit, based on the measurement direction information and contact information, if the stylus is in contact with the object to be measured and the direction of the movement instruction for the vertical movement unit is the same as the measurement direction, performs a minute retraction movement in the opposite direction to the movement instruction direction before moving the vertical movement unit in the direction of the movement instruction.

[0009] In the surface shape measuring device of the second embodiment, if the stylus is not in contact with the object to be measured, the movement control unit moves the vertical movement unit in the direction of the movement instruction without first moving the vertical movement unit in the opposite direction to the movement instruction direction.

[0010] In the surface shape measuring apparatus of the third embodiment, if the direction of movement of the vertically moving part that has been instructed to move is opposite to the measurement direction, the movement control unit moves the vertically moving part in the direction of movement instruction without first moving the vertically moving part in the opposite direction to the direction of movement instruction.

[0011] In the surface shape measuring device of the fourth embodiment, the movement control unit performs minute retraction movements while maintaining contact between the stylus and the object to be measured.

[0012] In the surface shape measuring device of the fifth embodiment, when the movement control unit performs a minute retraction movement and then moves the vertical movement unit in the direction of the movement instruction at a specified speed, after performing the minute retraction movement, it moves the vertical movement unit in the direction of the movement instruction at a speed lower than the specified speed, and then moves the vertical movement unit in the direction of the movement instruction at the specified speed.

[0013] In the sixth embodiment of the surface shape measuring device, a setting unit is provided for setting the amount of movement of the vertical movement part during minute retraction movement.

[0014] In the surface shape measuring device of the seventh embodiment, the setting unit sets the amount of movement of the vertical movement part in minute retraction movement so that it is smaller than the difference between the inner diameter of the hole and the effective height of the stylus when measuring the surface shape of the inner surface of a hole formed in the object to be measured.

[0015] In the eighth embodiment of the surface shape measuring device, the detector has a measuring force application mechanism that can switch the direction of the measuring force applied to the stylus according to the measurement direction of the stylus to the object to be measured, and the measuring direction information acquisition unit acquires measuring direction information based on the switching state of the measuring force in the measuring force application mechanism.

[0016] In the ninth embodiment of the surface shape measuring apparatus, the apparatus further includes a tilt drive unit that tilts the detector with respect to the object to be measured by rotating around a direction perpendicular to both the direction of movement of the vertical movement unit and the direction of movement of the detector by the horizontal drive unit, and a rotation control unit that, upon receiving a rotation instruction for the tilt drive unit, controls the rotation of the tilt drive unit based on the rotation instruction, wherein if the direction of the rotation instruction for the tilt drive unit matches the direction in which the stylus contacts the object to be measured, the rotation control unit performs a minute retraction rotation movement by first rotating the tilt drive unit in the opposite direction to the rotation instruction direction, and then rotates the tilt drive unit in the direction of the rotation instruction.

[0017] The control method for a surface shape measuring device in the tenth embodiment is a control method for a surface shape measuring device that measures the surface shape of an object to be measured, the surface shape measuring device comprising: a detector having a stylus that contacts the surface of the object to be measured and a displacement detection unit that detects the displacement of the stylus; a column erected vertically with respect to a base on which the object to be measured is placed; a drive unit provided on the column; a vertical movement unit connected to the drive unit and slidable along the longitudinal direction of the column; and a horizontal drive unit supported by the vertical movement unit and holding the detector movably in a direction perpendicular to the longitudinal direction of the column, the device acquires measurement direction information indicating the measurement direction, which is the direction in which the stylus contacts the object to be measured; acquires contact information indicating whether or not the stylus is in contact with the object to be measured; receives a movement instruction for the vertical movement unit; and based on the measurement direction information and the contact information, if the stylus is in contact with the object to be measured and the direction of the movement instruction for the vertical movement unit is the same as the measurement direction, the device performs a minute retraction movement in the opposite direction to the movement instruction direction of the vertical movement unit before moving the vertical movement unit in the direction of the movement instruction. [Effects of the Invention]

[0018] This invention can minimize damage to the stylus, workpiece, or both. [Brief explanation of the drawing]

[0019] [Figure 1] Figure 1 is a schematic diagram of a surface shape measuring device. [Figure 2] Figure 2 is a schematic diagram of the horizontal drive unit and detector. [Figure 3] Figure 3 is a schematic diagram of the column and the vertical movement section. [Figure 4] Figure 4 is a diagram illustrating the force exerted on the vertically moving section by the column. [Figure 5] Figure 5 illustrates the movement of the stylus due to the switch from static friction to kinetic friction during the movement of the vertical moving part. [Figure 6] Figure 6 shows the results of measuring workpiece damage. [Figure 7] Figure 7 is a graph showing the relationship between the thrust required to start movement and the stopping time. [Figure 8] Figure 8 is a block diagram showing the configuration of a surface shape measuring device. [Figure 9] Figure 9 is a flowchart showing the control method for a surface shape measuring device. [Figure 10] Figure 10 is a diagram illustrating the minute retraction movement of the vertical movement unit and the movement in the specified direction when the measurement direction is downward. [Figure 11] Figure 11 is a diagram illustrating the speed command value, actual speed, and actual position of the vertical movement unit during minute retraction movement of the vertical movement unit and movement in the specified direction. [Figure 12] Figure 12 shows an example of the movement of the vertical movement unit when the stylus and the workpiece are not in contact. [Figure 13] Figure 13 shows an example of the movement of the vertical movement unit when the stylus and the workpiece are in contact, and the movement instruction direction and the measurement direction are in opposite directions. [Figure 14] Figure 14 is a diagram illustrating the slight retraction movement and movement in the specified direction when the measurement direction is upward. [Figure 15] Figure 15 is a diagram illustrating the setting of the amount of movement in minute evacuation movements. [Figure 16] Figure 16 is a schematic diagram of another form of surface shape measuring device. [Figure 17] Figure 17 is a diagram illustrating the minute retraction and rotational movement of the tilt drive unit and the rotation of the tilt drive unit. [Modes for carrying out the invention]

[0020] Preferred embodiments of the present invention will be described below with reference to the attached drawings.

[0021] <Surface shape measuring device> Figure 1 is a schematic diagram of the surface shape measuring device 10. As shown in Figure 1, the surface shape measuring device 10 measures the shape of the surface of the workpiece W, specifically the contour shape or surface roughness, etc. Here, the workpiece W corresponds to the object to be measured in the present invention. Also, among the mutually orthogonal XYZ directions in the figure, the XY plane, which includes the XY direction, is a plane parallel to the horizontal direction, and the Z direction is the vertical direction perpendicular to the horizontal direction.

[0022] The surface shape measuring device 10 comprises a flat plate-shaped base 12 with a flat top surface, a column 14, a vertical movement unit 16, a horizontal drive unit 18, a detector 20 having a stylus 22, an operation unit 24, a monitor 26, and a control device 30.

[0023] A workpiece W is placed on the upper surface of the base 12, which is parallel to the XY plane. A column 14 is erected vertically in the Z direction (perpendicular direction) relative to the upper surface of the base 12. A vertical movement part 16 is attached to the column 14 so as to be slidable along the longitudinal direction of the column 14.

[0024] The horizontal drive unit 18 is supported by the vertical movement unit 16. The horizontal drive unit 18 holds the detector 20 so that it can move in a direction perpendicular to the longitudinal direction of the column 14 (X direction). By driving the horizontal drive unit 18, the detector 20 (stylus 22) can be moved in the X direction relative to the workpiece W.

[0025] The control unit 24 uses, for example, a keyboard, mouse, control panel, and control buttons, and accepts input of various operations from the operator.

[0026] The monitor 26 uses various displays, such as a known liquid crystal display. This monitor 26 displays the surface shape measurement results from the surface shape measuring device 10, various setting screens, and various operation screens.

[0027] The control device 30 includes an arithmetic circuit composed of various processors and memory. These processors include CPUs (Central Processing Units), GPUs (Graphics Processing Units), ASICs (Application Specific Integrated Circuits), and programmable logic devices [e.g., SPLDs (Simple Programmable Logic Devices), CPLDs (Complex Programmable Logic Devices), and FPGAs (Field Programmable Gate Arrays)]. The various functions of the control device 30 may be implemented by a single processor, or by multiple processors of the same or different types.

[0028] <Horizontal drive unit> Figure 2 is a schematic diagram of the horizontal drive unit 18 and the detector 20. As shown in Figure 2, the horizontal drive unit 18 comprises a rail 40, a slider 42, a ball screw 44, a motor 46, and an X-position detection mechanism 48.

[0029] Rail 40 extends along the X direction. A slider 42 is mounted on rail 40 so as to be movable along the X direction. A ball screw 44 is provided along rail 40. The slider 42 is screwed onto the ball screw 44.

[0030] A motor 46 is attached to rotate the ball screw 44. The motor 46 rotates the ball screw 44, and this rotational motion is converted into linear motion by the slider 42 and the ball screw 44, allowing the detector 20 attached to the slider 42 to move in the X direction (horizontal direction).

[0031] The X-position detection mechanism 48 can detect the position of the slider 42 in the X direction, thereby detecting the X-position of the detector 20, i.e., the X-position of the detector 20 relative to the workpiece W. The detection result of the X-position detection mechanism 48 is input to the control device 30.

[0032] <detector> As shown in Figure 2, the detector 20 comprises a stylus 22, an arm 50, a pivot point 52, a measuring force application mechanism 54, and a displacement detection unit 56.

[0033] The pivot point 52 supports the arm 50 so that it can swing freely around a rotation axis (pivot axis) parallel to the Y direction.

[0034] The arm 50 is pivotably supported on the pivot point 52. For example, the arm 50 can be composed of an arm tip 50A extending in one direction in the X direction (opposite to the column 14) and provided with a stylus 22, and an arm base end 50B extending in the other direction in the X direction.

[0035] By making the arm tip 50A and the arm base 50B detachable, multiple types of styluses 22 can be easily replaced according to the shape of the workpiece W.

[0036] A stylus 22 (also called a contact or measuring probe) is provided at the tip end of the arm tip 50A. The stylus 22 contacts the surface of the workpiece W. The stylus 22 is displaced in the Z direction as the arm 50 swings around the pivot point 52. The stylus 22 also traces (scans) the surface of the workpiece W along the X direction as the detector 20 is moved in the X direction by the horizontal drive unit 18.

[0037] The measuring force application mechanism 54 applies a measuring force, which is a biasing force directed toward the workpiece W, to the stylus 22 when the stylus 22 is brought into contact with the workpiece W. As a result, the tip of the stylus 22 comes into contact with the surface of the workpiece W.

[0038] The measuring force application mechanism 54 is configured to switch the direction in which the measuring force applied to the stylus 22 is applied, according to the measurement direction of the stylus 22 with respect to the workpiece W.

[0039] As shown in Figure 2, when the workpiece W is located below the stylus 22 in the Z direction, a downward measuring force is applied to the stylus 22 in the Z direction. On the other hand, when the workpiece W is located above the stylus 22 in the Z direction, an upward measuring force is applied to the stylus 22 in the Z direction.

[0040] The measurement direction of the measuring force application mechanism 54 is set by the control device 30. A spring, weight, or the like can be used as the measuring force application mechanism 54. The configuration of the measuring force application mechanism 54 is not limited as long as it can apply a measuring force.

[0041] The displacement detection unit 56 can detect the rotation angle or displacement in the Z direction due to the oscillation of the stylus 22. The detection result of the displacement detection unit 56 is input to the control device 30. As the displacement detection unit 56, for example, a linear variable differential transformer (LVDT), a linear scale, or an arc scale can be used. The displacement detection unit 56 is not limited as long as it can detect the displacement of the stylus 22.

[0042] <Column and vertical movement section> Figure 3 is a schematic diagram of the column 14 and the vertical movement section 16. As shown in Figure 3, the column 14 has a columnar housing that extends perpendicularly (in the Z direction) to the base 12 (see Figure 1).

[0043] Column 14 has an internal storage space in which a ball screw 62 is mounted. The ball screw 62 extends along the Z-direction of column 14. The upper end of the ball screw 62 protrudes from column 14.

[0044] A motor 64 for rotating the ball screw 62 is provided at the upper end of the ball screw 62, and the ball screw 62 and motor 64 function as a drive unit for driving the vertical movement unit 16. A Z position detection mechanism 66 is provided to detect the position (amount of movement in the Z direction) of the vertical movement unit 16. For example, an encoder or a Z position scale can be applied as the Z position detection mechanism 66. However, the Z position detection mechanism 66 is not particularly limited as long as it can detect the position of the vertical movement unit 16 in the Z direction. The detection result of the Z position detection mechanism 66 is input to the control device 30.

[0045] The vertical movement section 16 includes a column insertion hole 70 through which the column 14 can be inserted, a nut 72, a sliding material 74, and a pre-pressure mechanism 76.

[0046] As shown in Figure 3, the column insertion hole 70 of the vertical moving section 16 extends in the Z direction, and the column 14 is inserted through it.

[0047] The nut 72 of the vertical movement unit 16 is screwed onto the ball screw 62 that constitutes the drive unit, thereby connecting the vertical movement unit 16 and the drive unit. By rotating the ball screw 62 with the motor 64, this rotational motion is converted into linear motion by the nut 72 and the ball screw 62, causing the nut 72 to move along the longitudinal direction of the ball screw 62. The direction and speed of movement of the vertical movement unit 16 are controlled by movement instructions and speed instructions from the control device 30.

[0048] Each surface constituting the column insertion hole 70 of the vertical moving section 16 is provided with a sliding material 74 that frictionally slides against the side surface of the column 14 when the vertical moving section 16 moves vertically along the column 14. Furthermore, a pre-pressure mechanism 76 is provided on each sliding material 74 to apply a pressing force to the sliding material 74 against the column 14.

[0049] The relative position between the vertical moving part 16 and the column 14 is determined by the movement of the nut 72 due to the rotation of the ball screw 62, and this relative position is maintained by the frictional force of the sliding material 74.

[0050] The vertical movement portion 16 moves along the longitudinal direction of the column 14 via this nut 72, sliding along the side surface of the column 14 with friction.

[0051] <Background of the Invention> In the aforementioned surface shape measuring device 10, the inventors conducted thorough studies on the breakage of the stylus 22 and the workpiece W, and as a result, identified the following problems, leading to the present invention. The problems identified by the inventors will now be explained.

[0052] When the vertical moving part 16 supporting the detector 20 starts moving from a stationary position on the column 14, the vertical moving part 16 may start moving abruptly due to the switch from static friction to dynamic friction.

[0053] Figure 4 is a diagram illustrating the forces acting on the vertical movement section 16 and the column 14. For ease of understanding, the pressurization mechanism 76 and gravity have been omitted.

[0054] Figure 1004A shows the state when the stationary vertical moving part 16 moves downward along the longitudinal direction of the column 14. As shown in 1004A, the vertical moving part 16 and the column 14 are subjected to a normal force F NF , thrust F T and static friction force F S To receive.

[0055] Normal force F NF This is the reaction force to the pressing force applied to the sliding material 74 by the pre-pressure mechanism 76. Normal force F NF This force is perpendicular to the longitudinal direction of column 14 and directed toward the sliding material 74. Normal force F NF The size is determined by the pressing force of the pressurization mechanism 76.

[0056] Thrust F T This is the force exerted on the nut 72 by the rotation of the motor 64, and is an upward or downward force along the longitudinal direction of the column 14. Thrust F T The size and orientation are determined by the motor 66 controlled by the control device 30.

[0057] The static frictional force F S is a force determined by the coefficient of static friction and the normal force F NF and becomes a force in the opposite direction to the thrust force F T . The coefficient of static friction is determined by the materials of the column 14 and the sliding member 74, surface properties, etc.

[0058] To move the vertical moving part 16, the output torque of the motor 64 is increased until it balances with the static frictional force F S , and the thrust force F T is increased. The output of the motor 64 is controlled by a control device 30 (not shown).

[0059] 1004B shows a state where the vertical moving part 16 has started to move downward along the longitudinal direction of the column 14. As shown in 1004B, the vertical moving part 16 and the column 14 are subject to the normal force F NF , the thrust force F T and the dynamic frictional force F D .

[0060] The dynamic frictional force F D is a force determined by the coefficient of dynamic friction and the normal force F NF and becomes a force in the opposite direction to the thrust force F T .

[0061] Generally, since the coefficient of dynamic friction is smaller than the coefficient of static friction, the static frictional force F S > the dynamic frictional force F D , and as shown in 1004B, the frictional force decreases. As a result, the vertical moving part 16 moves downward with a large acceleration.

[0062] 1004C shows a state where after starting to move, the vertical moving part 16 is moving downward along the longitudinal direction of the column 14.

[0063] After the vertical moving part 16 starts to move, as shown in 1004C, the vertical moving part 16 and the column 14 are subject to the normal force F NF , the thrust force F T and the dynamic frictional force F D .

[0064] To move the vertical movement unit 16 at the target speed, the kinetic friction force F D The output torque of motor 64 is suppressed to balance this, and the thrust F T The output of the motor 64 is controlled by the control device 30 (not shown) to reach the target speed according to the detection result of the Z position detection mechanism 66.

[0065] In state 1004C, a stable kinetic friction force F exists between the vertical moving part 16 and the column 14. D Therefore, the movement of the vertical movement unit 16 is stably controlled by the control device 30.

[0066] Next, the movement of the stylus 22 due to the switch from static friction to dynamic friction when the vertical moving part 16 starts moving from a stationary state will be explained based on Figure 5. In Figure 5, the horizontal drive part 18 and the detector 20 are omitted for ease of understanding.

[0067] 1005A, 1005B, and 1005C in Figure 5 correspond to 1004A, 1004B, and 1004C in Figure 4, respectively.

[0068] In Figure 5, the workpiece W is positioned below the stylus 22, and the measurement direction is downward, and the movement direction of the vertical movement unit 16 is also downward. Therefore, this is the case when the movement direction of the vertical movement unit 16 instructed by the control device 30 is the same as the measurement direction.

[0069] 1005A indicates a state in which the stylus 22 is in contact with the workpiece W, and the vertical movement unit 16 is in a stopped state, and the control device 30 is attempting to move the vertical movement unit 16 downward along the longitudinal direction of the column 14 as indicated by arrow A. The vertical movement unit 16 is subjected to thrust F T static friction force F S The vertical movement section 16 will not move until it is balanced.

[0070] 1005B indicates the state where the friction switches from static to dynamic and the vertical moving part 16 begins to move. The static friction force F is generated during the switch from static to dynamic friction. SFrom kinetic friction force F D As a result, an initial energy E is generated, and this energy E is contained within the entire system. In this case, if the stylus 22 is in contact with the workpiece W, the energy E is transmitted from the tip of the stylus 22 to the workpiece W. Then, receiving a repulsive force R from the workpiece W, the stylus 22 springs up in the direction of arrow B.

[0071] 1005C shows the state in which the vertical moving part 16 is sliding along the longitudinal direction of the column 14 at a constant speed. At this time, the stylus 22, which was flipped up in 1005B, falls as shown by arrow C, collides with the workpiece W, and returns to its normal position. This collision causes damage (dents) to the workpiece W or damage to the stylus 22.

[0072] Figure 6 shows the results of measuring the needle marks (workpiece indentations) on the workpiece W after the stylus 22 struck the workpiece W, using a white-light interference microscope (manufactured by Tokyo Seimitsu Co., Ltd.: product name "Opt-scope"). 1006A shows the results when the rebound of the stylus 22 is small, and 1006B shows the results when the rebound of the stylus 22 is large. The areas enclosed by circles in the figure indicate the position and depth of the needle marks.

[0073] 1006A and 1006B respectively indicate the surface height (μm) of workpiece W using shades of color. The surface height range for 1006A and 1006B is from -4.0 (μm) to 3.0 (μm).

[0074] According to 1006A, the circled area has a depth of approximately 2.5 μm, while according to 1006B, the circled area has a depth of approximately 4.0 μm. The fracture depth in 1006B is deeper than that in 1006A, and it can be seen that the fracture depth increases as the amount of rebound of the stylus 22 increases.

[0075] It is also conceivable to predict the energy E mentioned above in advance and control the movement of the vertical movement unit 16. However, the thrust F required to start moving depends on the time the vertical movement unit 16 is stationary on the column 14. TBecause the parameters change, it was difficult to predict and control the movement of the vertical movement unit 16 in advance.

[0076] Figure 7 is a graph showing the relationship between the thrust required to initiate movement and the stopping time. The horizontal axis represents the stopping time [s], and the vertical axis represents the thrust required to initiate movement [arb.: arbitrary unit]. As shown in the graph of Figure 7, the thrust F required to initiate movement depends on the time the vertical movement unit 16 is stopped on the column 14. T The thrust increases. The relationship between stopping time and thrust increase is presumed to depend on the material and temperature of the column 14 and the sliding material 74, and the adhesion of the sliding material 74 to the column 14 is considered to be one of the contributing factors.

[0077] Note that the thrust F required to initiate movement is also important. T The larger the energy E becomes, the more the drive system (belt and lead screw) accumulates energy E through elastic deformation, which is then released all at once when movement begins, giving the vertical movement section 16 a rapid acceleration. As a result, the stylus 22 springs up, causing damage to both the stylus 22 and the workpiece W.

[0078] Furthermore, in order to reduce the energy E, the pressing force applied from the pre-pressure mechanism 76 to the sliding material 74 is reduced, and the static friction force F S It is also possible to reduce the static friction force F. S Reducing this value would weaken the holding force of the vertical movement part 16 relative to the column 14, raising concerns about a decrease in the positioning accuracy of the vertical movement part 16 and the occurrence of drift, such as movement even when stopped.

[0079] <Control of surface shape measuring device> To solve the above-mentioned problems, the inventors discovered that when the stylus 22 and the workpiece W are in contact, and the measurement direction, which is the direction in which the stylus is brought into contact with the workpiece W, is the same as the direction in which the vertical movement unit 16 is instructed to move, the vertical movement unit 16 can be moved slightly backward in the opposite direction to the instruction direction before being moved in the instruction direction. This discovery minimizes damage to the stylus 22, the workpiece W, or both, leading to the invention of this invention.

[0080] The control of the vertical movement unit 16 of the surface shape measuring device 10 will be described below.

[0081] Figure 8 is a block diagram showing an example of the configuration of the surface shape measuring device 10.

[0082] The control device 30 includes a control unit 100, a storage unit 102, an input unit 104, a display control unit 106, a detection data acquisition unit 108, a movement control unit 110, a measuring force application control unit 112, a measuring direction information acquisition unit 114, a contact information acquisition unit 116, and a movement amount setting unit 118.

[0083] The control unit 100 manages the overall operation of the surface shape measuring device 10. Based on acquired or input information, the control unit 100 executes various programs and transmits control signals, various data, processing results, various programs, etc., to each unit.

[0084] The storage unit 102 stores various programs, detection data, processing results based on the detection data, etc. The storage unit 102 is composed of, for example, ROM, RAM, hard disk, etc.

[0085] The input unit 104 acquires information input from the operation unit 24. The input unit 104 transmits signals corresponding to the input information to each unit, such as the control unit 100.

[0086] The display control unit 106 transmits a signal to the monitor 26 that corresponds to the information to be displayed on the monitor 26. The monitor 26 displays the information represented by the signal transmitted from the display control unit 106.

[0087] The detection data acquisition unit 108 acquires detection data from the displacement detection unit 56, the X-position detection mechanism 48, and the Z-position detection mechanism 66. The displacement amount of the stylus 22 is detected from the displacement detection unit 56, the amount of movement of the detector 20 in the X-axis direction (horizontal direction) is detected from the X-position detection mechanism 48, and the amount of movement of the vertical movement unit 16 in the Z-axis direction (vertical direction) is detected from the Z-position detection mechanism 66.

[0088] The movement control unit 110 controls the movement, direction of movement, and speed of the vertical movement unit 16 and the horizontal drive unit 18 based on a movement instruction signal from the control unit 100 or a movement instruction signal manually input from the operation unit 24 via the input unit 104. The direction of movement and speed of movement can be controlled, for example, by the rotation direction and rotation speed of the motors 46 and 64.

[0089] As will be described later, the movement control unit 110, based on the movement direction specified for the vertical movement unit 16, the measurement direction information, and the contact information, determines that the stylus 22 is in contact with the workpiece W and that the movement instruction direction of the vertical movement unit 16 and the measurement direction are the same, and then performs a small retraction movement of the vertical movement unit 16 in the opposite direction to the movement instruction direction before moving the vertical movement unit 16 in the movement instruction direction.

[0090] The measuring force application control unit 112 controls the operation, measuring force, and measuring direction of the measuring force application mechanism 54 provided in the detector 20. The measuring force application control unit 112 is controlled based on signals from the control unit 100 or signals input from the operation unit 24 via the input unit 104.

[0091] The measurement direction information acquisition unit 114 acquires measurement direction information indicating the measurement direction, which is the direction in which the stylus 22 is brought into contact with the workpiece W. The measurement direction information acquisition unit 114 acquires measurement direction information regarding the up and down direction of measurement from the measurement direction setting in the control unit 100 or the switching state of the measuring force application mechanism 54.

[0092] The contact information acquisition unit 116 acquires contact information indicating whether or not the stylus 22 is in contact with the workpiece W. The contact information acquisition unit 116 acquires contact information indicating whether or not contact is present from the information from the displacement detection unit 56 of the detector 20.

[0093] The movement amount setting unit 118 sets the amount of movement of the vertical movement unit 16 during the minute retraction movement described later. The movement amount setting unit 118 can acquire the amount of movement input from the operation unit 24 via the input unit 104. A signal containing information about the amount of movement set by the movement amount setting unit 118 is transmitted to the movement control unit 110.

[0094] Figure 9 is a flowchart of the control of the surface shape measuring device 10 in this embodiment. The control of the surface shape measuring device 10 will be explained based on Figure 9.

[0095] In this explanation, we will use the example shown in Figure 1, where the workpiece W is placed on the upper surface of the base 12, and the stylus 22 is facing downwards relative to the workpiece W, with the measurement direction being downwards.

[0096] In the surface shape measuring device 10 shown in Figure 1, the workpiece W is placed on the base 12, and the vertical movement unit 16 and the horizontal drive unit 18 are driven to bring the stylus 22 into contact with the surface of the workpiece W. The stylus 22, to which measuring force is applied by the measuring force application mechanism 54, traces (scans) the surface of the workpiece W along the X direction as the detector 20 is moved in the X direction by the horizontal drive unit 18.

[0097] When measuring the workpiece W, situations arise where it is necessary to change the relative position between the detector 20 (stylus 22) and the workpiece W, or when the measurement of the workpiece W is completed, requiring the vertical movement unit 16 to be moved in the same direction as the measurement direction or in the opposite direction to the measurement direction. In such situations, the control method of the embodiment can be suitably applied.

[0098] As shown in Figure 9, measurement direction information is acquired (step S10), which indicates the measurement direction in which the stylus 22 is brought into contact with the workpiece W. As previously described, the measurement direction information is acquired by the measurement direction information acquisition unit 114 from the measurement direction setting in the control unit 100 or the switching state of the measuring force application mechanism 54. Here, measurement direction information for a downward measurement direction is acquired.

[0099] Next, contact information indicating whether or not the stylus 22 is in contact with the workpiece W is acquired (step S12). As previously described, the contact information indicating whether or not contact is present is acquired by the contact information acquisition unit 116 from the information from the displacement detection unit 56 of the detector 20.

[0100] Next, the movement control unit 110 receives a movement instruction for the vertical movement unit 16 (step S14). As previously described, the movement control unit 110 receives a movement instruction for the vertical movement unit 16 from the control unit 100 or the operation unit 24. However, the movement control unit 110 does not move the vertical movement unit 16 until it has performed the determination in the following steps S16 and / or S18.

[0101] Next, the movement control unit 110 determines whether the stylus 22 is in contact with the workpiece W based on the contact information acquired by the contact information acquisition unit 116 (step S16). In step S16, if the movement control unit 110 determines that there is contact between the stylus 22 and the workpiece W, it makes a Yes determination. If the determination is Yes, the process proceeds to step S18.

[0102] On the other hand, in step S16, if the movement control unit 110 determines that there is no contact between the stylus 22 and the workpiece W, it will be determined as No. If the determination is No, the process proceeds to step S22.

[0103] Next, the movement control unit 110 determines whether the direction of movement of the vertical movement unit 16 that has been instructed to move is the same as the measurement direction, based on the measurement direction information acquired by the measurement direction information acquisition unit 114 (step S18). In step S18, if the movement control unit 110 determines that the direction of movement and the measurement direction are the same, it makes a Yes determination. If the determination is Yes, the process proceeds to step S20.

[0104] On the other hand, in step S18, if the movement control unit 110 determines that the movement instruction direction and the measurement direction are opposite, it will be determined as No. If the determination is No, the process proceeds to step S22.

[0105] Next, the movement control unit 110 performs a small retraction movement, temporarily moving the vertical movement unit 16 in the opposite direction to the movement instruction direction (step S20). In step S20, the movement control unit 110 commands the motor 64 to move a small amount in the opposite direction to the movement instruction direction.

[0106] Next, the movement control unit 110 moves the vertical movement unit 16 in the direction of the movement instruction (step S22). In step S22, the movement control unit 110 commands the motor 64 to move the vertical movement unit 16 in the direction of the movement instruction to the designated target position.

[0107] Next, with reference to Figure 10, the minute retraction movement of the vertical movement unit 16 and the movement in the direction of movement instruction in steps S20 and S22 will be described. In Figure 10, the workpiece W is located below the stylus 22 and the measurement direction is downward.

[0108] In 1010A, the stylus 22 and the workpiece W are in contact, and the measurement direction D M This indicates that the direction of movement instruction D is the same as the direction of movement instruction D. In this case, in step S20, the movement control unit 110 temporarily moves the vertical movement unit 16 slightly backward in the direction of movement direction M1 (upward), which is indicated by the arrow opposite to the direction of movement instruction D.

[0109] 1010C is a graph with time on the horizontal axis and velocity on the vertical axis. As shown in 1010C, during the minute retraction movement of 1010A, the movement control unit 110 controls the vertical movement unit 16 to a velocity V bk Then, for a certain period of time, it is moved slightly backward in the direction of movement M1.

[0110] When the vertical moving part 16 is moved slightly backward in the direction of movement M1, the vertical moving part 16 starts moving rapidly due to the switch from static friction to dynamic friction.

[0111] However, the vertical movement unit 16 is in the measurement direction D M Since it is in the opposite direction (the direction of movement M1), even if the stylus 22 is in contact with the workpiece W, no energy is transferred from the tip of the stylus 22 to the workpiece W. The stylus 22 does not receive a reaction force from the workpiece W, so the stylus 22 does not spring up. In other words, since the vertical movement part 16 moves a small amount in the direction away from the workpiece W first, no energy (impact) is applied to the workpiece W, so damage to the stylus 22 and the workpiece W can be minimized.

[0112] Next, as shown in 1010B, in step S22, the movement control unit 110 moves the vertical movement unit 16, which has made a small retraction movement, in the direction of movement direction M2 (downward) indicated by the arrow, which is the movement instruction direction D.

[0113] As shown in 1010C, when moving in the movement instruction direction D of 1010B, the movement control unit 110 controls the vertical movement unit 16 to speed V fw1 Then, for a certain period of time, move in the direction M2, which is the direction of movement instruction D, and then, speed V fw1 Speed ​​V specified from fw2 It is accelerated to move in the direction of movement M2, which is the movement instruction direction D. When 1010B moves in the movement instruction direction D, it switches to dynamic friction, so the vertical movement part 16 can be moved stably in the movement instruction direction D.

[0114] Furthermore, during the movement of the vertical movement section 16, the switch from the movement direction M1 of the minute retraction movement to the movement direction M2 of the movement instruction direction D is performed in a short time. Therefore, there is no time for the force to switch to static friction, or adhesion of the sliding material 74 due to the passage of time (see Figure 7) can be minimized. As a result, it is possible to suppress the sudden start of movement of the vertical movement section 16 when movement in the movement instruction direction D begins.

[0115] In either step S20 or step S22, the energy required for the stylus 22 to move toward the workpiece W can be minimized, thereby minimizing damage to the workpiece W and the tip of the stylus 22, contributing to improved lifespan of the stylus 22 and better maintenance of the workpiece W. Furthermore, since there is no need to provide actuators or the like on the detector 20, design constraints can be alleviated.

[0116] In step S20, it is preferable to perform a minute retraction while maintaining contact between the stylus 22 and the workpiece W. If the stylus 22 is in contact with the workpiece W, it is possible to avoid the stylus 22 colliding with the workpiece W when the vertical movement unit 16 moves in the movement direction M2 of the movement instruction direction D.

[0117] When moving in the direction D of the movement instruction for 1010B, as shown in 1010C, the operation command from the movement control unit 110 is "move in the direction D of the movement instruction with speed V fw2 In the case of "moving by", first, V fw1 <V fw2 A velocity V such that fw1 The vertical movement unit 16 is moved in the direction of the movement instruction D for a certain period of time, and then at the specified speed V fw2 Accelerate to the specified direction and move in the direction D.

[0118] In other words, the movement in the instructed direction D is performed in a movement sequence consisting of two steps: movement in the instructed direction D at a low speed, and movement in the instructed direction D at the instructed speed.

[0119] For example, when switching from the movement direction M1 of a slight retraction movement to the movement direction M2 of the movement instruction direction D, the specified speed V fw2 When the vertical movement unit 16 is moved by the command, a large speed difference may occur, potentially generating a large impact. Therefore, by configuring it in two steps, speed V fw2 Before reaching speed V fw2 A slower speed V fw1 By performing the movement in this manner, the impact can be mitigated, and the tip of the stylus 22 and the workpiece W can be preserved more effectively. However, the movement in the direction of movement M2 is not limited to two steps. For example, one step, three steps, etc., can be applied.

[0120] Next, based on Figure 11, the speed command value, actual speed, and actual position of the vertical movement unit 16 when switching from the movement direction M1 of the minute retraction movement to the movement direction M2 of the movement instruction direction D will be explained.

[0121] Figure 1011A is a graph with time on the horizontal axis and the speed command value on the vertical axis, showing the speed command value commanded from the movement control unit 110 to the motor 64 for each time period. As shown in 1011A, the speed command value V bk , V fw1 , V fw2 A signal with a waveform (square wave and triangular wave) is transmitted to the motor 64.

[0122] 1011B is a graph with time on the horizontal axis and the actual velocity on the vertical axis, showing the actual velocity of the vertical moving part 16 over time. Similarly, 1011C is a graph with time on the horizontal axis and the position of the vertical moving part 16 on the vertical axis, showing the actual position of the vertical moving part 16 over time. As indicated by the dashed circle, in minute time intervals, the initial movement is thrust F due to the adhesion between the sliding material 74 and the surface of the column 14. T Due to insufficient thrust, the vertical movement section 16 did not move, and the thrust F of the motor 64 was insufficient. T This indicates that when the height rises, the vertical movement section 16 begins to move.

[0123] Furthermore, as shown in 1011C, as circled with a solid line, when the vertical movement direction M1 of the vertical movement unit 16 switches to the movement direction M2, the time the vertical movement unit 16 remains in the same position is very short, resulting in the thrust F shown in the graph of Figure 7. T It is unlikely that there will be an increase. The generation of a large amount of energy during the switch from movement direction M1 to movement direction M2 can be suppressed.

[0124] Next, an example of the movement of the vertical movement unit 16 when the stylus 22 and the workpiece W are not in contact will be explained based on Figure 12. That is, the case where step S16 results in a "No" determination and the process proceeds to step S22.

[0125] In 1012A, the stylus 22 and the workpiece W are not in contact, and the measurement direction D M This indicates the case where the direction is opposite to the movement instruction direction D. In this case, in step S22, the movement control unit 110 moves the vertical movement unit 16 in the movement direction M1 which is the same direction as the movement instruction direction D (upward).

[0126] 1012C is a graph with time on the horizontal axis and velocity on the vertical axis, and it corresponds to the movement of 1012A. As shown in 1012C, the movement control unit 110 controls the vertical movement unit 16 to a velocity V fw1 Then, for a certain period of time, move in the direction M1 which is the movement instruction direction D, and then, speed V fw1 Speed ​​V specified fromfw2 The vehicle is accelerated to move in the direction M1, which is the direction of movement instruction D. However, movement in direction M1 is not limited to two steps.

[0127] In 1012B, the stylus 22 and the workpiece W are not in contact, and the measurement direction D M This indicates that the direction of movement instruction D is the same as the direction of movement instruction D. In this case, in step S22, the movement control unit 110 moves the vertical movement unit 16 in the movement direction M1 which is the same direction as the direction of movement instruction D (downward).

[0128] 1012D is a graph with time on the horizontal axis and velocity on the vertical axis, and it corresponds to the movement shown in 1012B. As shown in 1012D, the movement control unit 110 controls the vertical movement unit 16 at velocity V fw1 Then, for a certain period of time, move in the direction M1 which is the movement instruction direction D, and then, speed V fw1 Speed ​​V specified from fw2 The vehicle is accelerated to move in the direction M1, which is the direction of movement instruction D. However, movement in direction M1 is not limited to two steps.

[0129] In Figure 12, the vertical movement unit 16 is moved in the movement direction M1, which is the movement instruction direction D, without first moving the vertical movement unit 16 in the opposite direction to the movement instruction direction D.

[0130] Next, based on Figure 13, the stylus 22 and the workpiece W are in contact, and the movement instruction direction D and the measurement direction D M Let's explain an example of the movement of the vertical movement unit 16 when the directions are opposite. Specifically, this is the case where step S16 is determined to be Yes, step S18 is determined to be No, and the process proceeds to step S22.

[0131] In 1013A, the stylus 22 and the workpiece W are in contact, and the measurement direction D M This indicates the case where the direction is opposite to the movement instruction direction D. In this case, in step S22, the movement control unit 110 moves the vertical movement unit 16 in the movement direction M1 which is the same direction as the movement instruction direction D (upward).

[0132] Figure 1013B is a graph with time on the horizontal axis and velocity on the vertical axis. As shown in 1013B, the movement control unit 110 controls the vertical movement unit 16 at velocity V fw1 Then, for a certain period of time, move in the direction M1 which is the movement instruction direction D, and then, speed V fw1 Speed ​​V specified from fw2 The vehicle is accelerated to move in the direction M1, which is the direction of movement instruction D. However, movement in direction M1 is not limited to two steps.

[0133] In Figure 13, the vertical movement unit 16 is moved in the movement direction M1, which is the movement instruction direction D, without first moving the vertical movement unit 16 in the opposite direction to the movement instruction direction D.

[0134] Next, based on Figure 14, we will explain the minute retraction movement and movement in the movement instruction direction when the workpiece W is positioned above the stylus 22 and the measurement direction is upward. The measurement direction is different from that in Figure 10.

[0135] 1014A is measured in direction D M The needle is facing upwards, the stylus 22 is in contact with the workpiece W, and the measurement direction D M This indicates that the direction of movement instruction D is the same as the direction of movement instruction D. In this case, in step S20, the movement control unit 110 temporarily moves the vertical movement unit 16 slightly backward in the direction of movement direction M1 (downward), which is indicated by the arrow opposite to the direction of movement instruction D.

[0136] 1014C is a graph with time on the horizontal axis and velocity on the vertical axis. As shown in 1014C, during the minute retraction movement of 1014A, the movement control unit 110 controls the vertical movement unit 16 to a velocity V bk Then, for a certain period of time, it is moved slightly backward in the direction of movement M1.

[0137] Next, as shown in 1014B, in step S22, the movement control unit 110 moves the vertical movement unit 16, which has made a small retraction movement, in the direction of movement direction M2 (upward) indicated by the arrow, which is the movement instruction direction D.

[0138] As shown in 1014C, when moving in the movement instruction direction D of 1014B, the movement control unit 110 controls the vertical movement unit 16 to speed V fw1 Then, for a certain period of time, move in the direction M2, which is the direction of movement instruction D, and then, speed V fw1 Speed ​​V specified from fw2 It accelerates to a certain point and moves in the direction of movement M2, which is the direction of movement instruction D.

[0139] In Figure 14, as in Figure 10, the energy required for the stylus 22 to move toward the workpiece W can be minimized in either step S20 or step S22, thereby minimizing damage to the workpiece W and the tip of the stylus 22, contributing to improved lifespan of the stylus 22 and preservation of the workpiece W.

[0140] Although the explanation is omitted here, even when the measurement direction is upward, the vertical movement unit 16 can be moved by the movement control unit 110, similar to Figures 12 and 13. In other words, the vertical movement unit 16 can be moved in the movement direction M1, which is the movement instruction direction D, without first moving the vertical movement unit 16 in the opposite direction to the movement instruction direction D.

[0141] Next, the setting of the amount of movement in minute retraction movement will be explained based on Figure 15. Figure 15 shows an example where the surface shape of the inner surface of a hole formed in the workpiece W is measured.

[0142] As shown in 1015A, a hole H with an inner diameter D1 is formed in the workpiece W. A stylus 22 facing downward in the measurement direction is attached to the tip of the arm 50.

[0143] It is preferable to set the amount of movement of the vertical movement unit 16 during the minute retraction movement using the movement amount setting unit 118 so that the stylus 22, located inside the hole H, does not collide with the inner surface of the hole H on the side of the movement direction M1 when the vertical movement unit 16 makes a minute retraction movement in the movement direction M1.

[0144] For example, displacement M D The inner diameter of the hole D1 and the effective height of the stylus E are... HIt can be obtained from the difference by the following formula.

[0145] Moving amount M D <Inner diameter D1 - Effective height E of the stylus H Here, the effective height E of the stylus H is the sum of the height of the stylus 22 and the height of the arm 50.

[0146] As shown in 1015B, similar to 1015A, a hole H with an inner diameter D1 is formed in the work W. On the other hand, a stylus 22A with the measurement direction downward and a stylus 22B with the measurement direction upward are attached to the tip of the arm 50.

[0147] In 1015B as well as in 1015A, the moving amount M D is the difference between the inner diameter D1 of the hole and the effective height E of the stylus H and can be obtained by the following formula.

[0148] Moving amount M D <Inner diameter D1 - Effective height E of the stylus H Here, the effective height E of the stylus H is the sum of the height of the stylus 22A, the height of the stylus 22B, and the height of the arm 50.

[0149] In FIG. 15, by inputting the inner diameter D1 and the effective height E of the stylus H from the operation unit 24, the moving amount M D can be calculated and set by the moving amount setting unit 118. Also, by inputting the moving amount M D from the operation unit 24, the moving amount M D can be set by the moving amount setting unit 118.

[0150] The movement control unit 110 causes the vertical movement unit 16 to perform a minute retraction movement so as not to exceed the moving amount M D set by the moving amount setting unit 118. When performing the minute retraction movement, since the stylus 22 (22B) does not collide with the surface in the direction of the movement direction M1 of the hole H, it is possible to more effectively protect the work W and the stylus 22.

[0151] Next, another form of the surface shape measuring device 10A will be described based on Figure 16.

[0152] As shown in Figure 16, the surface shape measuring device 10A comprises a flat base 12, a column 14, a vertical movement unit 16, a horizontal drive unit 18, a detector 20 equipped with a stylus 22, an operation unit 24, a monitor 26, a control device 30, and a tilt drive unit 60.

[0153] The surface shape measuring device 10A differs from the surface shape measuring device 10 in that it includes a tilt drive unit 60.

[0154] The tilt drive unit 60 rotates around a rotation axis 60A that is perpendicular to both the direction of movement of the vertical movement unit 16 and the direction of movement of the detector 20 by the horizontal drive unit 18.

[0155] The horizontal drive unit 18 is connected to the vertical movement unit 16 via the tilt drive unit 60. The tilt drive unit 60 rotates around the rotation axis 60A, thereby tilting the detector 20 relative to the workpiece W. This allows the stylus 22 provided on the detector 20 to be tilted according to the inclination of the surface (measurement surface) of the workpiece W.

[0156] The control device 30A has the same configuration as the control device 30, and also includes a rotation control unit 120 that controls the rotation of the tilt drive unit 60.

[0157] When the rotation control unit 120 receives a rotation instruction from the control unit 100 or the like, it controls the rotation of the tilt drive unit 60.

[0158] Figure 17 illustrates the case in which the tilt drive unit 60 performs a small retraction rotational movement in the opposite direction to the rotation instruction direction and rotation in the direction that coincides with the rotation instruction direction.

[0159] As shown in 1017A, the rotation control unit 120 controls the rotation instruction direction R of the tilt drive unit 60 that has been instructed to rotate. D If the direction in which the stylus 22 contacts the workpiece W coincides with the rotation direction RD The tilt drive unit 60 is rotated in the opposite direction, R1, to perform a small retraction rotational movement.

[0160] Next, as shown in 1017B, the rotation control unit 120 moves the tilt drive unit 60 slightly backward in the rotation direction R1, and then moves the tilt drive unit 60 in the rotation instruction direction R D Rotate in the direction of rotation R2.

[0161] Even when the detector 20 is rotated by the tilt drive unit 60, damage to the workpiece W and the tip of the stylus 22 can be minimized.

[0162] Furthermore, if the rotation instruction direction is opposite to the contact direction, the tilt drive unit 60 is rotated in the rotation instruction direction without performing a small retraction rotational movement.

[0163] The rotation control unit 120 can determine whether the rotation direction matches the contact direction based on the horizontal position of the detector 20, the type of stylus 22, and the measurement direction of the detector.

[0164] <Effects of the Embodiment> As described above, according to the surface shape measuring device 10(10A) of the embodiment, when a movement instruction is received to move the vertical moving part 16 along the longitudinal direction of the column 14, the movement control unit 110, based on the contact information acquired by the contact information acquisition unit 116 and the measurement direction information acquired by the measurement direction information acquisition unit 114, performs a minute retraction movement to move the vertical moving part 16 in the opposite direction to the movement instruction direction before moving the vertical moving part 16 in the movement instruction direction if the stylus 22 is in contact with the workpiece W and the direction of the movement instruction of the vertical moving part 16 is the same as the measurement direction. This makes it possible to prevent the effects associated with the switch from static friction to dynamic friction at the start of movement of the vertical moving part 16 (such as damage to the stylus 22 or workpiece W).

[0165] Furthermore, according to the surface shape measuring device 10(10A) of the embodiment, if either of the following conditions is met—that the stylus 22 is not in contact with the workpiece W, or that the direction of the instructed vertical movement unit 16 and the measurement direction are opposite—the movement control unit 110 controls the vertical movement unit 16 to move in the direction of the instructed movement without first moving the vertical movement unit 16 in the opposite direction to the instructed movement direction. In other words, in such cases, there is little to no effect associated with the switching from static friction to dynamic friction at the start of movement of the vertical movement unit 16. Therefore, by moving the vertical movement unit 16 in the direction of the instructed movement without performing a minute retraction, it becomes possible to efficiently change the relative position between the detector 20 (stylus 22) and the workpiece W.

[0166] Furthermore, according to the surface shape measuring device 10(10A) of the embodiment, the movement control unit 110 performs minute retraction movement while maintaining contact between the stylus 22 and the workpiece W. As a result, the minute retraction movement is performed without the stylus 22 and the workpiece W separating, so when the vertical movement unit 16 is moved in the direction of the movement instruction after the minute retraction movement, it is possible to avoid the stylus 22 colliding with the workpiece W from a position away from the workpiece W. As a result, it is possible to further prevent damage to the stylus 22 and the workpiece W.

[0167] While embodiments of the present invention have been described above, the present invention is not limited to the examples above, and various improvements and modifications may be made without departing from the spirit of the invention. Several modifications will be described below.

[0168] <Example 1> In the embodiment described above, when the stylus 22 is in contact with the workpiece W and the direction of the instructed movement of the vertically moving part 16 is the same as the measurement direction, the control is performed to move the vertically moving part 16 in the opposite direction to the instructed movement direction before moving the vertically moving part 16 in the instructed movement direction. However, the control is not limited to this. For example, even when the stylus 22 is not in contact with the workpiece W, if the direction of the instructed movement of the vertically moving part 16 is the same as the measurement direction, the control may be performed to move the vertically moving part 16 in the opposite direction to the instructed movement direction before moving the vertically moving part 16 in the instructed movement direction. In other words, regardless of whether the stylus 22 is in contact with the workpiece W, the decision of whether or not to perform a minute retraction may be made based on whether or not the direction of the instructed movement of the vertically moving part 16 is the same as the measurement direction.

[0169] <Modification 2> In the embodiment described above, the movement control unit 110 performs control to perform a minute retraction movement while maintaining contact between the stylus 22 and the workpiece W, but the control is not limited to this. For example, the minute retraction movement may be performed until the contact between the stylus 22 and the workpiece W is released (non-contact state). Alternatively, depending on the thrust required to start the vertical movement unit 16 and the time spent stopped on the column 14, the control unit may selectively switch between performing a minute retraction movement while maintaining contact between the stylus 22 and the workpiece W, and performing a minute retraction movement until the contact between the stylus 22 and the workpiece W is released (non-contact state).

[0170] <Variation 3> In the embodiment described above, the contact information acquisition unit 116 acquires contact information indicating whether or not the stylus 22 is in contact with the surface of the workpiece W based on information from the displacement detection unit 56 of the detector 20, but the form of acquiring contact information is not limited to this. For example, a camera may be attached to a position (such as the base 12, detector 20, or horizontal drive unit 18) where the measurement position (contact position of the stylus 22) on the surface of the workpiece W can be observed, and contact information may be acquired based on the image information captured by the camera. Alternatively, the user may directly observe the contact state of the stylus 22 with the surface of the workpiece W. In this case, the contact information acquisition unit 116 acquires the observation result by the user (contact state of the stylus 22 with the surface of the workpiece W) input from the operation unit 24 to the input unit 104. [Explanation of Symbols]

[0171] 10...Surface shape measuring device, 10A...Surface shape measuring device, 12...Base, 14...Column, 16...Vertical movement unit, 18...Horizontal drive unit, 20...Detector, 22...Stylus, 22A...Stylus, 22B...Stylus, 24...Operation unit, 26...Monitor, 30...Control device, 30A...Control device, 40...Rail, 42...Slider, 46...Motor, 48...X position detection mechanism, 50...Arm, 50A...Arm tip, 50B...Arm base, 52...Pivot point, 54...Measuring force application mechanism, 5 6...Displacement detection unit, 60...Tilting drive unit, 60A...Rotation shaft, 64...Motor, 66...Z position detection mechanism, 70...Column insertion hole, 72...Nut, 74...Sliding material, 76...Pressure mechanism, 100...Control unit, 102...Storage unit, 104...Input unit, 106...Display control unit, 108...Detection data acquisition unit, 110...Movement control unit, 112...Measurement force application control unit, 114...Measurement direction information acquisition unit, 116...Contact information acquisition unit, 118...Movement amount setting unit, 120...Rotation control unit, W...Workpiece

Claims

1. A measuring device that measures an object by bringing a stylus into contact with the surface of the object to be measured, The stylus has a movable part that can move in an approach-to-across direction, moving closer to and further away from the surface of the object to be measured, A control unit that moves the stationary moving part to the away side so that the stylus is away from the surface, and then moves the moving part to the approach side so that the stylus is approaching the surface, A measuring device equipped with the following features.

2. The system includes a detection unit that detects the contact state between the surface of the object to be measured and the stylus, If the detection unit detects the contact state, the control unit moves the moving part to the separation side and then moves the moving part to the approach side; if the detection unit does not detect the contact state, it moves the moving part to the approach side without moving the moving part to the separation side. The measuring device according to claim 1.

3. A control method for a measuring device that measures an object by bringing a stylus into contact with the surface of the object to be measured, and which includes a movable part that can move in an approach-to-across direction so as to move closer to and further away from the surface of the object to be measured, The control step includes moving the stationary moving part to the away side where the stylus moves away from the surface, and then moving the moving part to the approach side where the stylus approaches the surface, A method for controlling a measuring device.

4. The detection step includes detecting the contact state between the surface of the object to be measured and the stylus, The control step, if the contact state is detected in the detection step, moves the moving part to the separation side and then moves the moving part to the approach side, and if the contact state is not detected in the detection step, moves the moving part to the approach side without moving the moving part to the separation side. A control method for the measuring device according to claim 3.

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