JP6598011B2 - Linear motor device and control method - Google Patents

Description

  The present invention relates to a linear motor device and a control method.

  When mounting a workpiece such as an electronic component on a substrate, a machining device that presses the workpiece against the substrate is used. In such a machine tool, a linear motor or the like is used as means for pressing the workpiece (Patent Document 1). In such a machine tool, it is necessary to press the workpiece with a load above a certain level in order to securely attach the workpiece to the substrate, but it is required to make the load as small as possible in order to prevent damage to the workpiece or the substrate. The That is, it is required to control the load applied to the workpiece with high accuracy.

JP 2009-194015 A

  However, there is a problem in that the accuracy of controlling the load applied to the workpiece is reduced due to variations in sliding resistance of motors and guide devices used in machine tools and changes in sliding resistance over time.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a linear motor device and a control method capable of improving the accuracy of a load applied to a workpiece as a pressurizing object.

In order to solve the above problem, one aspect of the present invention is a holding unit having a linear motor, a pressurizing unit that comes into contact with an object to be pressurized, and a straining unit, and the pressurizing unit via the straining unit. A holding unit that moves together with a mover provided in the linear motor, a sensor that measures strain of the strain unit, and a moving unit that moves the pressurizing unit toward the pressurizing object. The first control is performed when driving at a constant speed, and when the current flowing through the linear motor is equal to or less than a predetermined current limit value and the strain of the strain portion is detected by the sensor. A linear motor device comprising: a control unit that performs second control for driving the pressurizing unit toward the pressurizing object based on the strain amount of the strained unit measured by the sensor. is there.

One embodiment of the present invention includes a linear motor, a pressurizing unit that comes into contact with an object to be pressed, and a holding unit that holds the pressurizing unit via a strain unit and moves together with a mover provided in the linear motor. And a sensor for measuring the strain of the strain part, and a control method in a linear motor device, wherein the movable part is moved to drive the pressurization part toward the pressurization object at a constant speed. A strain of the strained portion measured by the sensor when the first step and a current flowing through the linear motor are equal to or less than a predetermined current limit value and the strain of the strained portion is detected by the sensor; And a second step of driving the pressurizing unit toward the pressurizing object based on the amount.

  According to this invention, the accuracy of the load applied to the pressurized object can be improved.

It is the schematic which shows the structure of the machine tool in embodiment. It is a figure which shows the attachment position of the strain gauge in a holding | maintenance part. It is a perspective view (partial sectional view) of a linear motor in an embodiment. It is a perspective view which shows the coil unit hold | maintained at the coil holder in this embodiment. It is a figure which shows the positional relationship of the magnet and coil of a linear motor in this embodiment. It is a perspective view which shows the principle of a magnetic sensor. It is a graph which shows the relationship between the direction of the magnetic field in an AMR sensor, and resistance value. It is a figure which shows the example of a shape of the ferromagnetic thin film metal of the magnetic sensor which detects the direction of a magnetic field, when magnetic field intensity is more than saturation sensitivity. It is a figure which shows the equivalent circuit (half bridge) of a magnetic sensor. It is a figure which shows the example of a shape of the ferromagnetic thin film metal of the magnetic sensor which detects the direction of a magnetic field. It is a figure which shows the positional relationship of a magnetic sensor and a rod. It is a figure which shows the example of a signal which a magnetic sensor outputs. It is a figure which shows the magnetic sensor using two sets of full bridge structures. It is a graph which shows the signal which the magnetic sensor of FIG. 13 outputs. It is a conceptual diagram which shows the positional relationship of a rod and a magnetic sensor, and the signal which a magnetic sensor outputs. It is a figure which shows the Lissajous figure drawn by the output VoutA and VoutB of a magnetic sensor. It is a figure which shows the magnetic sensor attached to an end case. It is a figure which shows the bush which is a bearing attached to the end case. It is a schematic block diagram which shows the structure of the control part in this embodiment. It is a flowchart which shows the operation | movement at the time of the machine tool in this embodiment pressing a workpiece | work initially on a board | substrate. It is a flowchart which shows the operation | movement which presses a workpiece | work to a board | substrate using the FL mode start position which the machine tool in this embodiment updated. FIG. 22 is a first waveform diagram showing changes in speed, current, and operation completion signal in the operation shown in FIG. 21. FIG. 22 is a second waveform diagram showing changes in speed, current, and operation completion signal in the operation shown in FIG. 21. It is a wave form diagram which shows the example of a change of the speed in the operation | movement shown in FIG. 21, an electric current, and distortion amount.

  Hereinafter, a linear motor device and a control method according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a machine tool 1 in the present embodiment. The machine device 1 as a linear motor device includes a rod-type linear motor 10, a connection plate 12 fixed to a rod 101 which is a mover of the linear motor 10, a hollow head shaft 13 fixed to the connection plate 12, A guide device 14 that guides the movement of the head shaft 13, a head portion 15 attached to the tip of the head shaft 13, and a tube 19 that is arranged along the inside of the head shaft 13 and is connected to the head portion 15 and has flexibility. And a control unit 20 that controls the linear motor 10.

  Since the head shaft 13 is connected to the rod 101 via the connection plate 12, when the rod 101 of the linear motor 10 moves, the head shaft 13 moves in the same direction with the same movement amount as the movement amount of the rod 101. The guide device 14 guides the movement of the rod 101 so that the movement direction of the head shaft 13 is the same as the movement direction of the rod 101 and the rod 101 moves smoothly. The head unit 15 includes a bracket 16, a holding unit 17, and a vacuum pad 18. The bracket 16 has a hollow hole, is attached to an end portion of the head shaft 13, and fixes the holding portion 17 to a surface opposite to the surface in contact with the head shaft 13. A tube 19 passes through the hollow hole of the bracket 16. The holding | maintenance part 17 is formed with the metal plate. The holding part 17 has at least two S-shaped leaf springs as strain parts. One end of both ends of the S-shaped leaf spring is fixed to the bracket, and the other end is fixed to the vacuum pad 18. The vacuum pad 18 is connected to a tube 19 that passes through the inside of the head shaft 13, the hollow hole of the bracket 16, and the hollow hole of the holding portion 17. The vacuum pad 18 as the pressurizing unit sucks the work 33 as the pressurizing object by sucking air through the tube 19. The work 33 is, for example, an electronic component. The strain portion may be a leaf spring other than an S-shape, or a curved leaf spring.

  The machine tool 1 drives the linear motor 10 and presses the workpiece 33 sucked by the vacuum pad 18 toward the substrate 31. The machine tool 1 presses the workpiece 33 against the substrate 31 with the vacuum pad 18 and attaches the workpiece 33 to the substrate 31 via the workpiece 33 or the adhesive 32 applied to the substrate 31. At this time, the control unit 20 drives the linear motor 10 based on the strain amount measured by the strain gauge 113 attached to the leaf spring of the holding unit 17, thereby pressing the workpiece 33 against the substrate 31 (load). To control. When the workpiece 33 is pressed with the vacuum pad 18, distortion occurs in the S-shaped leaf spring of the holding unit 17. Since the strain of the leaf spring changes according to the load that presses the workpiece 33, the pressing load can be measured by measuring the strain of the leaf spring. The strain gauge 113 as a sensor for measuring the strain of the leaf spring outputs a strain signal indicating the amount of strain of the leaf spring to the control unit 20.

  FIG. 2 is a diagram illustrating a mounting position of the strain gauge 113 in the holding unit 17. The strain gauge 113 is attached to a curved portion of the leaf spring. In addition, in FIG. 2, although the example which attaches the strain gauge 113 to the outer side of the location where the leaf | plate spring is curving is shown, you may attach the strain gauge 113 to the inner side of the curving location. Moreover, the strain gauge 113 may be attached to every leaf spring provided in the holding part 17, or the strain gauge 113 may be attached to some leaf springs or any one leaf spring.

  Hereinafter, the configuration of the linear motor 10 and the control unit 20 will be described. FIG. 3 is a perspective view (partially sectional view) of the linear motor 10 according to the present embodiment. In the linear motor 10, the rod 101 moves in the axial direction with respect to the coil housing case 102. A plurality of coils 104 held by a coil holder 105 are stacked (arranged) in the coil housing case 102. End cases 109 are attached to both end faces of the coil housing case 102. A bush 108 which is a bearing for guiding the linear motion of the rod 101 is attached to the end case 109.

  The rod 101 is made of a nonmagnetic material such as stainless steel and has a hollow space like a pipe. In the hollow space of the rod 101, a plurality of columnar magnets 103 (segment magnets) are stacked with the same poles facing each other. That is, each of the magnets 103 is stacked such that one of the adjacent magnets 103 is opposed to the N pole and the other of the adjacent magnets 103 is opposed to the S pole. A pole shoe 107 (magnetic pole block) made of a magnetic material such as iron is interposed between the magnets 103. The rod 101 penetrates through the laminated coils 104 and is supported by the coil housing case 102 so as to be movable in the axial direction.

  FIG. 4 is a perspective view showing the coil unit held by the coil holder 105 in the present embodiment. As shown in the figure, the coil 104 is a copper wire spirally wound and is held by a coil holder 105. That is, the plurality of coils 104 are formed by winding a copper wire along the outer periphery of the rod 101 around the direction in which the magnets 103 of the rod 101 are arranged, and each coil 104 is arranged with the magnets 103 arranged. Are arranged in the same direction as Since adjacent coils 104 need to be insulated, a ring-shaped resin spacer 105 a is interposed between the coils 104. A printed circuit board 106 is provided on the coil holder 105. A winding end 104 a of the coil 104 is connected to the printed circuit board 106.

  In the present embodiment, the coil housing case 102 is formed integrally with the coil 104 by insert molding in which the coil 104 and the coil holder 105 are set in a mold and molten resin or special ceramics is injected into the mold. As shown in FIG. 3, a plurality of fins 102 a are formed in the coil housing case 102 in order to improve the heat dissipation of the coil 104. The coil 104 held by the coil holder 105 is housed in an aluminum coil housing case 102, the gap between the coil 104 and the coil housing case 102 is filled with an adhesive, and the coil 104 and the coil holder 105 are coiled. You may fix to the storage case 102. FIG.

  FIG. 5 is a diagram showing a positional relationship between the magnet 103 and the coil 104 of the linear motor 10 in the present embodiment. A plurality of cylindrical magnets 103 (segment magnets) are arranged in the hollow space in the rod 101 so that the same poles face each other. Three coils 104 constitute a set of three-phase coils composed of U, V, and W phases. A coil unit is configured by combining a plurality of sets of three-phase coils. When a three-phase current having a phase difference of 120 ° is passed through a plurality of coils 104 divided into U, V, and W phases, a moving magnetic field that moves in the axial direction of the coil 104 is generated. The rod 101 obtains a thrust by the action of the magnetic field generated by each magnet 103 as a driving magnet and the moving magnetic field, and moves linearly relative to the coil 104 in synchronization with the speed of the moving magnetic field. I do.

  As shown in FIG. 3, a magnetic sensor 112 for detecting the position of the rod 101 is attached to one end case 109 that is a magnetic sensor housing case. The magnetic sensor 112 is disposed with a predetermined gap from the rod 101, and changes the direction of the magnetic field (magnetic vector direction) generated by the magnets 103 stacked in the rod 101 caused by the linear movement of the rod 101. To detect.

  As shown in FIG. 6, the magnetic sensor 112 includes a magnetic thin film metal composed of an Si or glass substrate 121 and an alloy composed mainly of a ferromagnetic metal such as Ni or Fe formed thereon. A resistance element 122 is included. The magnetic sensor 112 is called an AMR (Anisotropic-Magnetro-Resistance) sensor (anisotropic magnetoresistive element) because its resistance value changes in a specific magnetic field direction (reference: “technical document”, [online], Hamamatsu). Koden Co., Ltd., “Search August 13, 2015”, Internet <URL; http://www.hkd.co.jp/amr_tec_amr/>).

  FIG. 7 is a graph showing the relationship between the direction of the magnetic field and the resistance value in the AMR sensor. It is assumed that a current is passed through the magnetoresistive element 122, a magnetic field intensity that saturates the resistance change amount is applied, and the direction of the magnetic field (H) is given an angle change θ with respect to the current direction Y. At this time, as shown in FIG. 7, the resistance change amount (ΔR) becomes maximum when the current direction and the magnetic field direction are perpendicular (θ = 90 °, 270 °), and the current direction and the magnetic field direction are Minimum when parallel (θ = 0 °, 180 °). The resistance value R changes according to the following formula (1) according to the angle component between the current direction and the magnetic field direction. If the magnetic field strength is equal to or higher than the saturation sensitivity, ΔR becomes a constant, and the resistance value R is not affected by the magnetic field strength.

R = R0−ΔRsin2θ (1)
R0: resistance value of the ferromagnetic thin film metal in the absence of a magnetic field ΔR: resistance change amount θ: angle indicating the direction of the magnetic field

  FIG. 8 is a diagram illustrating an example of the shape of the ferromagnetic thin film metal of the magnetic sensor 112 that detects the direction of the magnetic field even when the magnetic field strength is equal to or higher than the saturation sensitivity. As shown in the figure, the thin ferromagnetic metal element (R1) formed in the vertical direction and the horizontal element (R2) are connected in series. The vertical magnetic field that causes the largest resistance change to the element (R1) is the smallest resistance change to the element (R2). The resistance values R1 and R2 are given by the following equations (2) and (3).

R1 = R0−ΔRsin2θ (2)
R2 = R0−ΔRcos2θ (3)

  FIG. 9 is a diagram showing an equivalent circuit (half bridge) of the magnetic sensor. The output Vout of this equivalent circuit is given by the following equation (4).

    Vout = R1 · Vcc / (R1 + R2) (4)

  Substituting equations (2) and (3) into equation (4) and rearranging results in the following equations (5-1) and (5-2).

Vout = Vcc / 2 + αcos 2θ (5-1)
α = ΔR · Vcc / 2 (2R0−ΔR) (5-2)

  FIG. 10 is a diagram showing an example of the shape of the ferromagnetic thin film metal of the magnetic sensor for detecting the direction of the magnetic field. As shown in the figure, if the shape of the ferromagnetic thin film metal is formed, the stability of the midpoint potential can be improved and amplified using the two outputs Vout + and Vout−.

  The change in the magnetic field direction and the output of the magnetic sensor 112 when the rod 101 moves linearly will be described. FIG. 11 is a diagram illustrating the positional relationship between the magnetic sensor 112 and the rod 101. As shown in the figure, the magnetic sensor 112 is disposed at the position of the gap 1 where a magnetic field strength equal to or higher than the saturation sensitivity is applied, and so that the change in direction of the magnetic field contributes to the sensor surface. At this time, when the magnetic sensor 112 moves relative to the distance λ of the positions A to E along the rod 101, the output of the magnetic sensor 112 is as follows.

  FIG. 12 is a diagram illustrating an example of signals output from the magnetic sensor 112. As shown in the figure, when the rod 101 linearly moves a distance λ, the direction of the magnetic field rotates once on the sensor surface. At this time, the voltage signal becomes a one-cycle sine wave signal. More precisely, the voltage Vout represented by the equation (5-1) is a sine wave signal for two cycles. However, if a bias magnetic field is applied at 45 ° with respect to the extending direction of the element of the magnetic sensor 112, the period is halved, and an output waveform of one period is obtained when the rod 101 moves linearly along λ.

  In order to know the direction of movement, as shown in FIG. 13, two sets of full-bridge elements may be formed on a single substrate so as to be inclined at 45 ° from each other. The outputs VoutA and VoutB obtained by the two sets of full bridge circuits are a cosine wave signal and a sine wave signal having a phase difference of 90 ° from each other, as shown in FIG.

  In the present embodiment, the magnetic sensor 112 formed on one substrate so that the two sets of full-bridge elements shown in FIG. 13 are inclined by 45 ° with respect to each other detects a change in the magnetic field direction of the rod 101. Therefore, as shown in FIG. 15, even if the mounting position of the magnetic sensor 112 is shifted from (1) to (2), a sine wave signal and a cosine wave signal (outputs VoutA and VoutB) output from the magnetic sensor 112. There is little change.

  FIG. 16 is a diagram showing a Lissajous figure drawn by the outputs VoutA and VoutB of the magnetic sensor 112. Since the change in the output of the magnetic sensor 112 is small, the size of the circle shown in FIG. 16 is difficult to change. For this reason, the direction θ of the magnetic vector 24 can be accurately detected. Even if the gap l between the rod 101 and the magnetic sensor 112 is not managed with high accuracy, the accurate position of the rod 101 can be detected, so that the mounting adjustment of the magnetic sensor 112 is facilitated. In addition, the rod 101 guided by the bush 108 can have a backlash, and the rod 101 can be slightly bent.

  FIG. 17 is a view showing the magnetic sensor 112 attached to the end case 109. The end case 109 is provided with a magnetic sensor housing portion 126 formed of a space for housing the magnetic sensor 112. After the magnetic sensor 112 is disposed in the magnetic sensor housing portion 126, the periphery of the magnetic sensor 112 is filled with a filler 127. Thereby, the magnetic sensor 112 is fixed to the end case 109. The magnetic sensor 112 has a temperature characteristic, and its output changes with changes in temperature. In order to reduce the influence of heat received from the coil 104, a material having a lower thermal conductivity than the coil housing case 102 is used for the end case 109 and the filler 127. For example, an epoxy resin is used for the coil housing case 102, and polyphenylene sulfide (PPS) is used for the end case 109 and the filler 127.

  FIG. 18 is a view showing a bush 108 that is a bearing attached to the end case 109. By providing the end case 109 with a bearing function, it is possible to prevent the gap between the rod 101 and the magnetic sensor 112 from fluctuating.

  FIG. 19 is a schematic block diagram illustrating a configuration of the control unit 20 in the present embodiment. The control unit 20 includes a position control unit 201, a switch unit 202, a speed control unit 203, a switch unit 204, a current control unit 205, a power converter 206, a current transformer (CT) 207, a speed calculation unit 208, a position A calculation unit 209, a speed switching position determination unit 210, a position determination unit 211, a completion signal generation unit 212, and a strain control unit 213 are provided. Hereinafter, the case where the position of the vacuum pad 18 when the rod 101 is raised most is set as the origin serving as the reference of the position of the vacuum pad 18 will be described.

  The position control unit 201 calculates a speed command based on a position command input from the outside and information indicating the position of the rod 101 provided in the linear motor 10 calculated by the position calculation unit 209. The position control unit 201 stores in advance the first speed to the fourth speed (FL1SPD to FL4SPD), and four speed commands based on the first speed to the fourth speed (first speed command to fourth speed). Command).

  The first speed command is from the predetermined origin of the rod 101 to the vicinity of the workpiece 33 (FL (Force Limit) mode start position) of the vacuum pad 18 of the head unit 15 attached to one end of the rod 101. This is a command indicating the speed at which the rod 101 moves when moving. In the first speed command, the upper limit value of the speed at which the rod 101 is moved is predetermined as the first speed (FL1SPD). For example, the maximum speed when the linear motor 10 moves the rod 101 is the first speed (FL1SPD).

  The second speed command is a command indicating the speed at which the rod 101 moves when the vacuum pad 18 moves from the vicinity of the work 33 until it contacts the work 33. In the second speed command, the speed at which the rod 101 is moved is predetermined as the second speed (FL2SPD). The second speed (FL2SPD) is a speed slower than the first speed (FL1SPD), and is set to a speed at which a pressure equal to or less than a certain level is applied to the work 33 when the vacuum pad 18 contacts the work 33.

  The third speed command is a command indicating a speed when the rod 101 and the vacuum pad 18 are moved away from the work 33 after the work 33 is mounted on the substrate 31 by pressing the vacuum pad 18 against the work 33. . In the third speed command, the speed at which the rod 101 is moved is predetermined as a third speed (FL3PSD). That is, the third speed command is a command used when the rod 101 and the vacuum pad 18 are moved toward the origin.

  The fourth speed command is a command indicating a speed when the rod 101 is moved toward the origin after the work pad 33 is mounted on the substrate 31 by pressing the vacuum pad 18 against the work 33. In the fourth speed command, the upper limit value of the speed at which the rod 101 is moved is predetermined as the fourth speed (FL4SPD). In addition, the fourth speed (FL4SPD) is set to be faster than the third speed (FL3SPD). For example, as with the first speed (FL1SPD), the fourth speed (FL4SPD) is set as the maximum speed when the linear motor 10 moves the rod 101.

  The switch unit 202 selects any one of the four speed commands output from the position control unit 201 based on the control of the position determination unit 211. The speed control unit 203 receives a speed command selected by the switch unit 202 and speed information indicating the speed of the rod 101 calculated by the speed calculation unit 208. Based on the deviation between the speed indicated by the speed command and the speed indicated by the speed information, the speed control unit 203 calculates a current value for changing the speed at which the rod 101 moves to the speed indicated by the speed command.

  Further, the speed control unit 203 outputs the calculated current value as an unrestricted current command, and outputs a limited current command that is a current command having a predetermined current limit value (FL2I) as an upper limit value. When the calculated current value is equal to or less than the current limit value (FL2I), the non-limit current command and the limit current command indicate the same current value. On the other hand, when the calculated current value is larger than the current limit value (FL2I), the non-limit current command indicates the calculated current value, and the limit current command indicates the current limit value (FL2I). The current limit value (FL2I) is generated with respect to the workpiece 33 when the thrust of the linear motor 10, the force pressing the workpiece 33 when the workpiece 33 is mounted on the substrate 31, and the vacuum pad 18 and the workpiece 33 are in contact with each other. It is predetermined based on the load.

  Based on the control of the position determination unit 211, the switch unit 204 is one of a current limit command and a non-limit current command output by the speed control unit 203 and a pressing current command output by the strain control unit 213. Select a command. The current control unit 205 calculates a voltage command that reduces the deviation between the current command selected by the switch unit 204 and the current value flowing through the linear motor 10 measured by the current transformer 207. The power converter 206 applies a voltage to each of the U, V, and W phase coils 104 of the linear motor 10 based on the voltage command calculated by the current control unit 205. The current transformer 207 is attached to a power line connecting the power converter 206 and the linear motor 10. The current transformer 207 measures the current value flowing through the power line. The current transformer 207 outputs a signal indicating the measured current value to the current control unit 205 and the speed switching position determination unit 210.

  The speed calculator 208 is a rod provided in the linear motor 10 based on the amount of change in the sine wave signal and cosine wave signal (outputs VoutA and VoutB) output from the magnetic sensor 112 attached to the linear motor 10. 101 is calculated. The position calculation unit 209 calculates the amount of movement of the rod 101 from the origin based on the amount of change in the sine wave signal and cosine wave signal (outputs VoutA and VoutB) output from the magnetic sensor 112. The position calculation unit 209 outputs position information indicating the position of the rod 101 to the position control unit 201, the speed switching position determination unit 210, and the position determination unit 211.

  Speed switching position determination unit 210 outputs a signal indicating the FL mode start position to position determination unit 211. The FL mode start position is a position at which the speed command is switched from the first speed command to the second speed command when the rod 101 and the vacuum pad 18 are moving toward the workpiece 33 and the substrate 31. Further, the speed switching position determination unit 210 outputs a signal indicating the speed switching position (FL3POS) to the position determination unit 211. The speed switching position (FL3POS) is a position where the speed command is switched from the third speed command to the fourth speed command when the rod 101 is moved toward the origin after the workpiece 33 is pressed against the substrate 31.

  In addition, when the processing for pressing the workpiece 33 is first performed, the speed switching position determination unit 210 outputs the previously stored initial switching position (FL2POSSUB) to the position determination unit 211 as the FL mode start position. When the vacuum pad 18 is first pressed against the workpiece 33, the speed switching position determination unit 210 presses the workpiece 33 by pressing the workpiece 33 based on the speed and position at which the rod 101 moves and the current flowing through the linear motor 10. The FL mode start position is updated so as to shorten the time required for the step of attaching to the substrate 31. After updating the FL mode start position, the speed switching position determination unit 210 outputs the FL mode start position to the position determination unit 211. The initial switching position is a position determined in advance according to the height of the workpiece 33, and the vacuum pad 18 and the rod 101 are set so as not to give unnecessary impact to the workpiece 33 when the vacuum pad 18 is brought into contact with the workpiece 33. This is the position where the deceleration starts. For example, the same position as the initial switching position (FL2POSSUB) is set in advance as the speed switching position (FL3POS).

  The position determination unit 211 selects one of the four speed commands output from the position control unit 201 based on the position command and the operation start signal input from the outside and the position information output from the position calculation unit 209. The switch 202 is controlled to select. Further, the position determination unit 211 controls the switch unit 204 based on the position command and the operation start signal, the position information, and the strain signal output from the strain gauge 113. The position determination unit 211 causes the switch unit 204 to select any one of the non-limit current command, the limit current command, and the pressing current command.

  When the vacuum pad 18 is pressing the workpiece 33 and the pressing load reaches a predetermined load, the completion signal generation unit 212 turns on and outputs an operation completion signal (UO2) to the outside. The position determination unit 211 determines whether or not the pressing load has reached a predetermined load based on the strain signal output from the strain gauge 113. The completion signal generation unit 212 turns on and outputs the operation completion signal (UO2) based on the determination result by the position determination unit 211.

  A strain signal is input from the strain gauge 113 to the strain controller 213. The strain controller 213 calculates a current value that flows through the linear motor 10 based on a deviation between a predetermined strain command value and the strain amount indicated by the strain signal. The current value calculated by the strain control unit 213 is a current value calculated based on PI control or PID control so that the deviation from the strain command value becomes zero, and the thrust generated for the rod 101 is the workpiece 33. It is a current value that becomes a load applied to. The strain control unit 213 outputs the calculated current value to the switch unit 204 as a pressing current command. The strain command value is determined based on the amount of strain generated in the leaf spring when the load applied to the workpiece 33 becomes a desired load when the linear motor 10 is driven and the vacuum pad 18 is pressed against the workpiece 33. Since the holding part 17 is provided with a plurality of S-shaped leaf springs, the average value and maximum value of the strain amount of each leaf spring, the average value and median value of the strain amount obtained by a plurality of trials, and the maximum value. The strain command value may be determined based on the value or the like.

  Next, the operation when the machine tool 1 first presses the workpiece 33 will be described. FIG. 20 is a flowchart showing an operation when the machine tool 1 in this embodiment first presses the workpiece 33 against the substrate 31. Here, a direction in which the rod 101 approaches the workpiece 33 and the substrate 31 is a CW direction, and a direction in which the rod 101 moves away from the workpiece 33 and the substrate 31 is a CCW direction. When a position command based on the position of the workpiece 33 is input from the outside, the control unit 20 starts driving the linear motor 10 and performs origin return to move the vacuum pad 18 to the origin (step S101).

  When the origin return is completed, the position determination unit 211 determines whether or not the operation start signal (UI2) is turned on from the outside (step S102), and waits until the operation start signal is turned on (step S102: NO). When the operation start signal is turned on (step S101: YES), the position determination unit 211 causes the switch unit 202 to select the first speed command and causes the switch unit 204 to select a non-limit current command (step S103). The movement of the vacuum pad 18 and the rod 101 toward the direction 33 (in the CW direction) is started (step S104).

  The position determination unit 211 determines whether or not the position of the vacuum pad 18 has reached the initial switching position (FL2POSSUB) (step S105), and the first speed until the vacuum pad 18 reaches the initial switching position (FL2POSSUB). The linear motor 10 is driven using the command (step S105: NO). When the vacuum pad 18 reaches the initial switching position (FL2POSUB) (step S105: YES), the position determination unit 211 causes the switch unit 202 to select the second speed command and causes the switch unit 204 to select the limit current command ( Step S106), the moving speed of the rod 101 is decelerated.

  After the second speed command is selected, the speed switching position determination unit 210 determines whether or not the moving speed of the rod 101 is equal to or lower than the second speed (FL2SPD) (step S107). The determination is repeated until the second speed (FL2SPD) or less is reached (step S107: NO). When the moving speed of the rod 101 becomes equal to or lower than the second speed (FL2SPD) (step S107: YES), the speed switching position determination unit 210 determines the difference (FL2POSMAIN1) between the current position of the vacuum pad 18 and the initial switching position (FL2POSSUB). ) And the calculated difference (FL2POSMAIN1) is stored (step S108).

  The speed switching position determination unit 210 determines whether or not strain is detected in the leaf spring of the holding unit 17 based on the strain signal output from the strain gauge 113 (step S109), and waits until strain is detected. (Step S109: NO). When the strain is detected (step S109: YES), the speed switching position determination unit 210 sets a position obtained by subtracting the difference (FL2POSMAIN1) calculated in step S108 from the current position of the vacuum pad 18 as a new FL mode start position. Store as (FL2POSMAIN2) (step S110). At this time, if the position determination unit 211 detects a strain in the same manner as the speed switching position determination unit 210, the position determination unit 211 causes the switch unit 204 to select the pressing current command output from the strain control unit 213 and starts feedback control based on the strain amount. (Step S111).

  In step S110, a predetermined distance Δd may be provided as a margin when a new FL mode start position (FL2POSMAIN2) is calculated. Specifically, a position obtained by subtracting the difference (FL2POSMAIN1) and the minute distance Δd from the current position of the vacuum pad 18 may be a new FL mode start position (FL2POSMAIN2). Further, the determination as to whether or not the strain is detected in the leaf spring of the holding unit 17 is performed by comparing a strain amount indicated by a strain signal output from the strain gauge 113 with a predetermined value, for example. The speed switching position determination unit 210 and the position determination unit 211 determine that distortion has occurred when the amount of distortion exceeds a predetermined value, and detect distortion. This predetermined value is determined so that the strain generated in the S-shaped leaf spring of the holding portion 17 when the vacuum pad 18 contacts the workpiece 33 can be detected. Further, when a plurality of strain gauges 113 are provided in the holding unit 17, it is determined that the strain is generated when the strain amount measured by any one strain gauge 113 becomes a predetermined value or more.

  The position determination unit 211 determines whether or not the strain amount is equal to or greater than the threshold value (step S112), and continues feedback control based on the strain amount until the strain amount reaches the threshold value (step S112: NO). . When the strain amount becomes equal to or greater than the threshold value (step S112: YES), the position determination unit 211 outputs a signal indicating that the strain amount has reached the threshold value to the completion signal generation unit 212. The completion signal generator 212 turns on the operation completion signal (UO2) and outputs it to the outside (step S113). The threshold value is determined based on the amount of strain when a desired load is applied to the workpiece 33.

  The position determination unit 211 determines whether or not the operation start signal input from the outside is off (step S114), and waits until the operation start signal is turned off (step S114: NO). When the operation start signal is turned off (step S114: YES), the position control unit 201 calculates a speed command according to the position command with the origin as the movement destination. The position determination unit 211 causes the switch unit 202 to select the third speed command, and causes the switch unit 204 to select the limit current command (step S115), and moves the rod 101 toward the origin (in the CCW direction). Start (step S116).

  The position determination unit 211 determines whether or not the vacuum pad 18 has reached the speed switching position (FL3POS) (step S117), and the vacuum pad 18 and the vacuum pad 18 until the vacuum pad 18 reaches the speed switching position (FL3POS). The movement of the rod 101 is continued (step S117: NO). When the vacuum pad 18 reaches the speed switching position (FL3POS) (step S117: YES), the position determination unit 211 causes the switch unit 202 to select the fourth speed command (step S118).

  The position determination unit 211 determines whether or not the vacuum pad 18 has reached the origin (step S119), and continues the movement of the vacuum pad 18 and the rod 101 until the vacuum pad 18 reaches the origin (step S119: NO). . When the vacuum pad 18 reaches the origin (step S119: YES), the position determination unit 211 outputs a signal indicating that the vacuum pad 18 has reached the origin to the completion signal generation unit 212, and the completion signal generation unit 212 operates. The completion signal is turned off (step S120), and the operation of first pressing the work 33 against the substrate 31 is completed.

  FIG. 21 is a flowchart showing an operation of pressing the workpiece 33 against the substrate 31 using the FL mode start position updated by the machine tool 1 in the present embodiment. When the position of the substrate 31 to which the workpiece 33 is attached or a position command based on the position of the workpiece 33 is input from the outside, the control unit 20 starts driving the linear motor 10 and returns the vacuum pad 18 to the origin. Is performed (step S201).

  When the origin return is completed, the position determination unit 211 determines whether or not the operation start signal (UI2) is turned on from the outside (step S202), and waits until the operation start signal is turned on (step S202: NO). When the operation start signal is turned on (step S202: YES), the position determination unit 211 causes the switch unit 202 to select the first speed command and causes the switch unit 204 to select a non-limit current command (step S203). The movement of the vacuum pad 18 and the rod 101 toward the direction 33 (in the CW direction) is started (step S204).

  The position determination unit 211 determines whether or not the position of the vacuum pad 18 has reached the FL mode start position (FL2POSMAIN2) (step S205), and continues until the vacuum pad 18 reaches the FL mode start position (FL2POSMAIN2). The linear motor 10 is driven using one speed command (step S205: NO). When the vacuum pad 18 reaches the FL mode start position (FL2POSMAIN2) (step S205: YES), the position determination unit 211 causes the switch unit 202 to select the second speed command and causes the switch unit 204 to select the limit current command. (Step S206), the moving speed of the rod 101 is decelerated.

  The position determination unit 211 determines whether or not strain is detected in the leaf spring of the holding unit 17 based on the strain signal output from the strain gauge 113 (step S207), and waits until strain is detected (step S207). Step S207: NO). When the strain is detected (step S207: YES), the position determination unit 211 causes the switch unit 204 to select the pressing current command output from the strain control unit 213, and starts feedback control based on the strain amount (step S208). ).

  The position determination unit 211 determines whether or not the strain amount is equal to or greater than the threshold value (step S209), and continues feedback control based on the strain amount until the strain amount reaches the threshold value (step S209: NO). . When the strain amount becomes equal to or greater than the threshold value (step S209: YES), the position determination unit 211 outputs a signal indicating that the strain amount has reached the threshold value to the completion signal generation unit 212. The completion signal generator 212 turns on the operation completion signal (UO2) and outputs it to the outside (step S210).

  The position determination unit 211 determines whether or not the operation start signal input from the outside is off (step S211), and waits until the operation start signal is turned off (step S211: NO). When the operation start signal is turned off (step S211: YES), the position control unit 201 calculates a speed command according to the position command with the origin as the movement destination. The position determination unit 211 causes the switch unit 202 to select the third speed command, and causes the switch unit 204 to select the limit current command (step S212), and moves the rod 101 toward the origin (in the CCW direction). Start (step S213).

  The position determination unit 211 determines whether or not the vacuum pad 18 has reached the speed switching position (FL3POS) (step S214), and until the vacuum pad 18 reaches the speed switching position (FL3POS) The movement of the rod 101 is continued (step S214: NO). When the vacuum pad 18 reaches the speed switching position (FL3POS) (step S214: YES), the position determination unit 211 causes the switch unit 202 to select the fourth speed command (step S215).

  The position determination unit 211 determines whether or not the vacuum pad 18 has reached the origin (step S216), and continues the movement of the vacuum pad 18 and the rod 101 until the vacuum pad 18 reaches the origin (step S216: NO). . When the vacuum pad 18 reaches the origin (step S216: YES), the position determination unit 211 outputs a signal indicating that the vacuum pad 18 has reached the origin to the completion signal generation unit 212, and the completion signal generation unit 212 operates. The completion signal is turned off (step S217), and the operation of pressing the work 33 against the substrate 31 is finished.

  FIG. 22 is a waveform diagram showing changes in speed, current, and operation completion signal in the operations from step S202 to step S210 in the operations shown in FIG. In the figure, the vertical axis indicates the position of the vacuum pad 18. When the operation start signal is turned on, the control unit 20 moves the vacuum pad 18 toward the work 33 at the first speed (FL1SPD). When the vacuum pad 18 reaches the FL mode start position (FL2POSMAIN2), the controller 20 decelerates the vacuum pad 18 from the first speed (FL1SPD) to the second speed (FL2SPD). The control unit 20 moves the vacuum pad 18 toward the workpiece 33 at the second speed (FL2SPD). When the vacuum pad 18 comes into contact with the workpiece 33 and the strain of the leaf spring is detected, the control unit 20 starts feedback control based on the strain amount, and the force pressing the vacuum pad 18 against the workpiece becomes a desired load. When this is detected by the distortion signal, the operation completion signal is turned on.

  FIG. 23 is a waveform diagram showing changes in speed, current, and operation completion signal in the operations from step S212 to step S217 in the operations shown in FIG. In the figure, the vertical axis indicates the position of the vacuum pad 18. After pressing the vacuum pad 18 against the work 33, the control unit 20 moves the vacuum pad 18 toward the origin at the third speed (FL3SPD) and raises it. When the vacuum pad 18 reaches the speed switching position, the control unit 20 moves the vacuum pad 18 toward the origin at a fourth speed (FL4SPD) that is faster than the third speed (FL3SPD). The control unit 20 reduces the moving speed of the rod 101 of the linear motor 10 so that the speed of the vacuum pad 18 becomes zero at the origin, and turns off the operation completion signal when the vacuum pad 18 reaches the origin.

  FIG. 24 is a waveform diagram showing an example of changes in speed, current, and strain in the operations shown in FIG. 21 from step S202 to step S209. In the figure, the horizontal axis indicates time, and the vertical axis indicates speed, current, and strain. When the operation start signal is turned on, the control unit 20 moves toward the workpiece 33 at the first speed (FL1SPD) by the position control based on the positions of the vacuum pad 18 and the rod 101, and starts the FL mode start position (FL2POSMAIN2). When reaching, decelerate to the second speed (FL2SPD). The control unit 20 controls the vacuum pad 18 at the second speed (FL2SPD) by thrust control (first control) that limits the current flowing through the linear motor 10 with a current limit value (FL2I) to keep the thrust below a certain value. It moves toward the workpiece 33 at a constant speed and below a certain thrust. When it is detected from the strain amount that the vacuum pad 18 is in contact with the workpiece 33 in a state where the current flowing through the linear motor 10 is equal to or less than the current limit value, the control unit 20 performs pressing control (second control) based on feedback control based on the strain amount. Control). The control unit 20 applies a desired load to the workpiece 33 by performing pressing control. Note that the velocity, current, and strain amount waveforms shown in FIG. 24 are merely examples, and change according to the thrust of the linear motor 10, the number of leaf springs provided in the holding portion 17, the elasticity and shape of the leaf springs, and the like. .

  The machine tool 1 according to the present embodiment moves the vacuum pad 18 toward the workpiece 33 at a speed and thrust below a certain level with the linear motor 10, and the vacuum pad 18 and the workpiece 33 based on the strain amount measured by the strain gauge 113. When the contact is detected, the linear motor 10 is controlled based on the strain amount. Since the amount of strain is proportional to the increase in the load pressing the vacuum pad 18 against the workpiece 33, the accuracy of the load applied to the workpiece 33 can be improved by the control based on the amount of strain.

  Further, the machine tool 1 according to the present embodiment starts the pressing control when the occurrence of strain is detected by any of the plurality of strain gauges 113. Thereby, as soon as the vacuum pad 18 comes into contact with the workpiece 33, it is possible to shift to pressing control, and a load can be applied to the workpiece 33 with high accuracy.

  The machine tool 1 decelerates to a second speed slower than the first speed before the vacuum pad 18 contacts the work 33 by control according to the position of the vacuum pad 18, so that an unnecessary impact is not given to the work 33. The vacuum pad 18 can be pressed against the work 33. Further, the holding unit 17 secures a hollow hole through which the tube 19 is passed so that the tube 19 can be connected to the vacuum pad 18, and holds the bracket 16 and the vacuum pad 18 with a leaf spring, thereby reducing the air flow path. The pressing force can be measured while ensuring. Further, by forming the holding portion 17 and providing the leaf spring with the strain gauge 113, the load accuracy can be improved without using a load cell. Further, by attaching the strain gauge 113 to the leaf spring, a slight strain due to a minute force can be detected, and the pressing force can be measured with high accuracy. In addition, the head portion 15 can be reduced in weight, and the influence on the operation performance due to the attachment of the strain gauge 113 can be reduced. Further, by measuring the load with the strain gauge 113, the pressing force can be accurately controlled even if there is a variation in the sliding resistance in the guide device 14 or a change in the sliding resistance with time. .

  Since the machine device 1 is provided with a strained portion (plate spring) between the vacuum pad 18 (pressure portion) and the guide device 14, even if the sliding resistance in the guide device 14 varies, Variations in the pressing force against the workpiece 33 can be eliminated.

  Further, when the work machine 1 first presses the work 33, it detects the distance (difference (FL2POSMAIN1)) required to decelerate from the first speed to the second speed, and the position where the vacuum pad 18 contacts the work 33. And a new FL mode start position (FL2POSMAIN2) from the difference (FL2POSMAIN1). Further, the machine tool 1 performs an operation of pressing the work 33 against the substrate 31 using the FL mode start position (FL2POSMAIN2) calculated when the work 33 is first pressed. That is, the machine tool 1 calculates the FL mode start position based on the position of the workpiece 33 detected when the workpiece 33 is first pressed and the separation required to decelerate from the first speed to the second speed. The workpiece 33 is pressed using the FL mode start position. Thereby, the machining apparatus 1 can shorten the section to be moved at the second speed, and can shorten the time required for pressing the workpiece 33 and the like.

  In the above-described embodiment, the case where the control unit 20 controls the rod type linear motor 10 has been described. However, the control unit 20 may control a flat type linear motor or a rotary motor. When the control unit 20 controls the rotary motor, the rotary motion of the motor may be converted into a linear motion using a ball screw or the like.

  In the above-described embodiment, the configuration in which the head portion 15 is attached to the head shaft 13 that moves together with the rod 101 has been described. However, the head portion 15 may be attached to one end of the rod 101. Moreover, although the structure which uses a strain gauge in order to measure the distortion | strain of a leaf | plate spring was demonstrated, as long as it is a sensor which can measure the distortion | strain of a leaf | plate spring, you may use sensors other than a strain gauge.

  Moreover, the determination (step S112 and step S208) in the pressing control of the above-described embodiment is based on either the maximum value, the average value, or the minimum value of each strain amount when there are a plurality of strain gauges 113. You may go. In addition, when calculating the deviation from the strain command value, the strain control unit 213 may calculate the deviation using any one of the maximum value, the average value, and the minimum value of each strain amount. As a result, it is possible to suppress variation in the load applied to the work 33 due to variations in the measurement values of the plurality of strain gauges 113.

  Also, whether the strain at which the current value flowing through the linear motor 10 is less than or equal to the current limit value (FL2I) is detected as the condition for starting the pressing control in the above-described embodiment (the condition in step S109 and step S207). You may change to the condition of. Thereby, when the linear motor 10 is generating the thrust unnecessary for the movement of the vacuum pad 18 and the rod 101, it cannot be made to transfer to pressing control. Further, the machine tool 1 according to the present embodiment performs the pressing control (second control) when the strain of the leaf spring (strain portion) is detected by the strain gauge 113 in a state where the current flowing through the linear motor 10 is equal to or less than the current limit value. Control), optimal control of pressing using the strain gauge 113 can be performed.

  Moreover, the above-mentioned control part 20 may have a computer system inside. In this case, the process performed by each unit included in the control unit 20 is stored in a computer-readable recording medium in the form of a program, and the program is read and executed by the computer, whereby the process of each functional unit is performed. Will be done. Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

  DESCRIPTION OF SYMBOLS 1 ... Machine tool (linear motor device), 10 ... Linear motor, 17 ... Holding part, 18 ... Vacuum pad (pressurizing part), 20 ... Control part, 33 ... Workpiece (pressurization object), 101 ... Rod (movable) Child), 113 ... Strain gauge (sensor)

Claims (5)

A linear motor;
A pressurizing part that comes into contact with the pressurized object;
A holding portion having a strain portion, holding the pressurizing portion via the strain portion, and moving with a mover provided in the linear motor;
A sensor for measuring strain of the strain section;
The first control is performed to move the movable element and drive the pressurizing unit toward the pressurizing target at a constant speed, and the current flowing through the linear motor is equal to or less than a predetermined current limit value, And when the strain of the strained part is detected by the sensor, the pressurizing part is changed to the pressurizing object based on the strain amount of the strained part measured by the sensor instead of the first control. A control unit that performs the second control to be driven toward,
A linear motor device. The strain portion has at least two leaf springs,
The sensor is provided for each leaf spring,
The control unit performs the second control when at least one of the plurality of sensors detects a strain of the leaf spring.
The linear motor device according to claim 1. When there are a plurality of the sensors,
In the second control, the control unit directs the pressurizing unit toward the pressurization object based on any one of a maximum value, an average value, and a minimum value of strain amounts measured by the plurality of sensors. Drive,
The linear motor apparatus as described in any one of Claim 1 or Claim 2. The control unit drives the mover in a direction away from the pressurization object after the amount of strain measured by the sensor is equal to or greater than a threshold value.
The linear motor apparatus as described in any one of Claims 1-3 . A linear motor, a pressurizing unit that comes into contact with an object to be pressed, a holding unit that holds the pressurizing unit via a straining unit and moves with a mover provided in the linear motor, and measures strain of the straining unit A control method in a linear motor device comprising:
A first step of moving the mover to drive the pressurizing unit toward the pressurizing object at a constant speed;
When the current flowing through the linear motor is equal to or less than a predetermined current limit value and the strain of the strained portion is detected by the sensor, the addition is performed based on the strain amount of the strained portion measured by the sensor. A second step of driving the pressure unit toward the pressurizing object;
A control method.

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