Grinding system, trajectory generation method, and product manufacturing method

Abstract

A grinding system 1 is provided with: a grinding apparatus 10 provided with a grinding tool 22 for grinding an object member 80; an applied pressure measuring device 14 that measures a grinding pressure acting on the object member 80 from the grinding tool 22; and a control device 12 that generates, on the basis of the three-dimensional shape of the surface of the object member 80 and the position and shape of a removal target 82 in the object member 80, a track for the grinding tool 22 to grind off the removal target 82, and controls the grinding apparatus 10 so as to move the grinding tool 22 along the track. The control device 12 generates the track such that the moving speed and / or the grinding pressure of the grinding tool 22 with respect to the object member 80 changes in accordance with the position of the grinding tool 22.

Description

[Technical field]

[0001] The present disclosure relates to a grinding system, a trajectory generating method, and a method for manufacturing a product, which grind a target to be removed, such as a defect present on the surface of a target material such as a steel product. [Background technology]

[0002] For example, in the manufacturing process of steel products, surface defects occur due to various factors during casting or rolling. Surface defects are removed by an operator grinding off the defective parts with a grinder. However, grinding work using a grinder involves various risks, such as the presence of a rotating body in close proximity to the operator, exposure of the operator to sparks, dust, or noise, and the operator contracting white finger disease due to vibrations during grinding. There is a shortage of manpower to carry out risky work. In addition, there is a demand to avoid risky work. From the viewpoints of labor saving and safety, there is a demand to automate the grinding work of removing defects.

[0003] Various methods have been proposed so far as methods for automating the grinding of defects. In the conventional methods, a problem has been that a step occurs at the boundary between the ground and unground parts of the target object when the defect is ground away. The step at the boundary between the ground and unground parts has a negative effect on the aesthetic appearance of the product. In addition, the step at the boundary between the ground and unground parts causes abrupt changes in the dimensions of the product surface. Abrupt changes in the dimensions of the product surface may cause the product to crack when a large force is applied to the product or when additional processing is performed on the product.

[0004] For example, Patent Document 1 discloses a method of periodically varying the contact angle during reciprocating motion of the grinder in the feed direction to change the contact area of ​​the grinding wheel so as to reduce the step that occurs at the boundary between the ground and unground areas. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-100759 Summary of the Invention [Problem to be solved by the invention]

[0006] Even in the method disclosed in Patent Document 1, a step occurs due to an overshoot that occurs when the grinding wheel of the grinder comes into contact with the material to be ground or when the grinding wheel separates from the material. When grinding while maintaining the contact force or pressing force of the grinding wheel constant using a force sensor, in order to reduce the overshoot when the grinding wheel comes into contact or separates, it is necessary to reflect the measurement result of the force sensor in the calculation of the grinding wheel trajectory while increasing the response speed of the control system. In this case, the cost of the control device or system becomes high. In addition, it takes a lot of time to tune the control system so that it can handle various steel types or grinding conditions.

[0007] The present disclosure aims to provide a grinding system, a trajectory generation method, and a product manufacturing method that can reduce steps that occur when grinding a removal target of a three-dimensional grinding target material such as a steel product. [Means for solving the problem]

[0008] A grinding system according to an embodiment of the present disclosure includes a grinding device having a grinding tool for grinding a target material, a pressure measuring device for measuring a grinding pressure applied to the target material by the grinding tool, and a control device for generating a trajectory of the grinding tool for grinding the target material based on a three-dimensional shape of a surface of the target material and a position and shape of a removal target of the target material, and for controlling the grinding device so that the grinding tool moves based on the trajectory. The control device generates the trajectory so that at least one of the moving speed of the grinding tool relative to the target material and the grinding pressure changes depending on the position of the grinding tool.

[0009] A trajectory generation method according to one embodiment of the present disclosure is a trajectory generation method for generating a trajectory for controlling a grinding tool that grinds a target material, and includes the steps of measuring the three-dimensional shape of the surface of the target material, recognizing the position and shape of a target for removal from the target material, and generating the trajectory based on the three-dimensional shape and attitude of the target material and the position and shape of the target for removal, such that at least one of the speed of the grinding tool relative to the target material or the grinding pressure acting on the target material from the grinding tool changes depending on the position of the grinding tool.

[0010] A manufacturing method for a product according to one embodiment of the present disclosure includes a step of controlling a grinding tool based on a trajectory generated by executing the above-mentioned trajectory generating method, and grinding a removal target of a target material. Effect of the Invention

[0011] According to the grinding system, trajectory generating method, and product manufacturing method disclosed herein, steps caused by grinding are reduced. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a grinding system according to the present disclosure. [Diagram 2] FIG. 2 is a side view showing an example of a grinding device. [Diagram 3] FIG. 3 is a view taken along the arrow A in FIG. 2. [Figure 4] FIG. 4 is a diagram showing an example of a trajectory of a grinding tool when grinding an object. [Diagram 5] FIG. 13 is a diagram showing an example of a trajectory of a grinding tool when the grinding tool enters an object. [Figure 6] 11A and 11B are diagrams showing an example of a trajectory of a grinding tool when it is separated from a target object. [Figure 7] 1 is a graph showing an example of a relationship between the position of the grinding tool and the speed of the grinding tool at each position. [Figure 8] 11 is a graph showing an example of a relationship between the position of the grinding tool and the grinding pressure at each position. [Figure 9]4 is a flowchart showing an example of a procedure of a grinding method according to the present embodiment. [Figure 10] 11 is a graph showing an example of the relationship between the position in the feed direction of the grinding tool and the grinding depth of the object at each position, obtained by the grinding method according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the grinding system, trajectory generation method, and product manufacturing method according to the present disclosure will be described with reference to the drawings. Each drawing is a schematic view and may differ from the actual product. In addition, the following embodiments are illustrative of an apparatus or method for embodying the technical idea of ​​the present disclosure, and are not intended to specify the configuration as described below. In other words, the technical idea of ​​the present disclosure can be modified in various ways within the technical scope described in the claims.

[0014] (Example of the configuration of grinding system 1) 1, a grinding system 1 according to an embodiment of the present disclosure includes a grinding device 10, a control device 12, a pressure measuring device 14, a shape measuring device 32, and a removal target recognizing device 30. The grinding system 1 grinds a target material 80 to be ground using the grinding device 10, and removes a removal target 82 included in the target material 80. An example of each component of the grinding system 1 will be described below.

[0015] <Grinding device 10> As shown in Figs. 1, 2 and 3, the grinding device 10 includes a grinding wheel 22 and a grinder 20 that rotates the grinding wheel 22. The grinding wheel 22 is configured in a disk shape. The grinder 20 rotates the grinding wheel 22 around an axis perpendicular to the paper surface of Fig. 3. The point at which the grinding wheel 22 contacts the target material 80 is also referred to as a processing reference point 24. The grinding device 10 grinds the surface of the target material 80 at the processing reference point 24. The grinding device 10 can grind the surface of the target material 80 into a planar shape by grinding the surface of the target material 80 while moving the processing reference point 24. The grinding device 10 controls the attitude of the grinding wheel 22 so that the processing reference point 24 is located behind the grinding wheel 22 with respect to the feed direction of the grinding wheel 22. In other words, the grinding device 10 controls the attitude of the grindstone 22 so that the angle between a plane of the grindstone 22 parallel to the paper surface of FIG. 3 and the feed direction of the grindstone 22 becomes an acute angle.

[0016] The grinding wheel 22 and the grinder 20 are also referred to as a grinding tool. The grinding device 10 includes a grinding tool. The grinding tool is not limited to a combination of the grinding wheel 22 and the grinder 20. The grinding tool may include devices having various other structures or shapes as long as the grinding tool can grind the target material 80.

[0017] The grinding device 10 includes a means for moving the grinding tool so as to control the position of the processing reference point 24 and the attitude of the grinding tool at the processing reference point 24. The grinding device 10 may be configured to include an arm robot as a means for moving the grinding tool. The grinding tool may be installed at the tip or midway of the arm robot. The arm robot may be configured as, for example, a multi-axis robot. The multi-axis robot may be configured to include, for example, six axes (rotation axes) and have degrees of freedom in six axial directions. The multi-axis robot may be configured to have degrees of freedom of movement in at least three axial directions. The multi-axis robot may be a vertical multi-joint type robot.

[0018] The means for moving the grinding tool is not limited to the arm robot, and may be configured to include devices having various other structures or shapes as long as the means for moving the grinding tool can control the position of the processing reference point 24 and the attitude of the grinding tool at the processing reference point 24.

[0019] <Control device 12> The control device 12 controls the grinding device 10 to grind and remove the removal target 82 included in the surface of the target material 80 based on information acquired from the shape measuring device 32, the removal target recognition device 30, or the pressure measuring device 14. The control device 12 may control the shape measuring device 32, the removal target recognition device 30, or the pressure measuring device 14. The control device 12 may be configured to include at least one processor, such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), so as to control each part of the grinding system 1. The control device 12 may be configured with one processor or multiple processors. The processor constituting the control device 12 may control each part of the grinding system 1 by reading and executing a program stored in a storage unit described later.

[0020] The control device 12 may include a storage unit. The storage unit stores various information or data. The storage unit may store, for example, a program executed in the control device 12, or data used in a process executed in the control device 12 or a result of the process. The storage unit may also function as a work memory for the control device 12. The storage unit may include, but is not limited to, a semiconductor memory. For example, the storage unit may be configured as an internal memory of a processor used as the control device 12, or may be configured as a hard disk drive (HDD) accessible from the control device 12. The storage unit may be configured as a non-transitory readable medium. The storage unit may be configured integrally with the control device 12, or may be configured separately from the control device 12.

[0021] The control device 12 may include a communication unit. The communication unit may be configured to include a communication interface for communicating with each component of the grinding system 1, such as the grinding device 10, the shape measuring device 32, the removal target recognition device 30, or the pressure measuring device 14, by wire or wirelessly. The communication interface may be configured to be capable of communicating with other devices. The communication unit may be configured to include an input / output port for inputting and outputting data between each component of the grinding system 1 or other devices. The communication unit may transmit and receive necessary data and signals between each component of the grinding system 1 or other devices. The communication unit may communicate based on a wired communication standard, or may communicate based on a wireless communication standard. For example, the wireless communication standard may include a cellular phone communication standard such as 3G, 4G, or 5G. The wireless communication standard may include, for example, IEEE802.11 or Bluetooth (registered trademark). The communication unit may support one or more of these communication standards. The communication unit is not limited to these examples and may communicate with other devices or input and output data based on various standards.

[0022] <Pressure measuring device 14> The pressure measuring device 14 measures the pressure acting from the grinding tool to the target material 80 when the target material 80 is ground with the grinding tool. The pressure acting from the grinding tool to the target material 80 is balanced with a reaction force acting from the target material 80 to the grinding tool. The pressure measuring device 14 may be configured to include various sensors such as a torque sensor or a pressure sensor.

[0023] <Shape measuring device 32> The shape measuring device 32 measures the three-dimensional shape of the surface of the target material 80 to be ground. The shape measuring device 32 may be configured to include a camera that captures an image of the target material 80. The shape measuring device 32 may output an image of the target material 80 as a measurement result of the three-dimensional shape of the surface of the target material 80.

[0024] The shape measuring device 32 may calculate the three-dimensional shape of the surface of the target material 80 as point cloud information, which is a set of three-dimensional coordinates of each point on the surface of the target material 80, and output the point cloud information as a measurement result of the three-dimensional shape of the surface of the target material 80. The shape measuring device 32 may be configured to include, for example, a depth camera that measures the distance to each point on the surface of the target material 80. The shape measuring device 32 may measure the three-dimensional coordinates of each point on the surface of the target material 80 based on the measurement result of the depth camera. The shape measuring device 32 may be configured to measure the three-dimensional coordinates of each point on the surface of the target material 80 by, for example, contacting a probe with the surface of the target material 80. The shape measuring device 32 may be configured to measure the three-dimensional coordinates of each point on the surface of the target material 80 by, for example, irradiating the target material 80 with laser light or the like and detecting the reflected light.

[0025] <Removal target recognition device 30> The removal target recognition device 30 recognizes the position and shape of the removal target 82 to be removed on the surface of the target material 80 based on the measurement result of the three-dimensional shape of the surface of the target material 80. The removal target 82 may include, for example, a convex portion occurring on the surface of the target material 80. The removal target recognition device 30 may recognize the position and shape of the removal target 82 included as a convex portion on the surface of the target material 80 by comparing the measurement result of the three-dimensional shape of the surface of the target material 80 with data of a normal three-dimensional shape. The removal target 82 may include, for example, a concave portion occurring on the surface of the target material 80. The removal target 82 may include surface defects such as dirt or rust that do not cause a change in the shape of the surface of the target material 80. The removal target 82 is not limited to the above-mentioned example, and may include various parts of the target material 80 that need to be removed.

[0026] The removal target recognition device 30 may be configured as a part of the control device 12. In other words, the control device 12 may acquire data of the three-dimensional shape of the surface of the target material 80 from the shape measurement device 32 and recognize the position and shape of the removal target 82.

[0027] (Example of operation of grinding system 1) In the grinding system 1, the shape measuring device 32 measures the three-dimensional shape of the surface of the target material 80 to be ground. The measurement data of the three-dimensional shape of the surface of the target material 80 may include the dimensions or the attitude of the target material 80. The measurement data of the three-dimensional shape of the surface of the target material 80 may be acquired as an image. The removal target recognition device 30 recognizes the removal target 82 included in the surface of the target material 80 based on the measurement data of the three-dimensional shape of the surface of the target material 80. The removal target recognition device 30 may recognize the position, shape, or dimensions of the removal target 82. The control device 12 controls the grinding device 10 based on the recognition result of the removal target 82 so that the removal target 82 is ground and removed by the grinding tool. An example of the operation of the grinding system 1 will be described below. It is assumed that the removal target 82 is a convex portion occurring on the surface of the target material 80.

[0028] The control device 12 may operate the grinding device 10 to grind the surface of the target material 80 for a predetermined time in order to remove the removal target 82 included in the surface of the target material 80. The control device 12 may operate the grinding device 10 to grind the surface of the target material 80 by a predetermined grinding amount.

[0029] Specifically, the control device 12 performs inverse kinematic calculations based on the position and shape or dimensions of the removal target 82 recognized by the removal target recognition device 30, and generates a trajectory for operating the grinding device 10 so as to press the grinding wheel 22 against the position of the removal target 82 and grind the removal target 82. The control device 12 controls the grinding device 10 so that the grinding tool moves based on the generated trajectory.

[0030] The trajectory includes information specifying the movement path of the machining reference point 24 of the grinding wheel 22. The trajectory may specify the movement path of the machining reference point 24 by including information specifying the movement speed of the machining reference point 24. The movement speed of the machining reference point 24 may be represented by a function with time as a parameter. When the movement speed of the machining reference point 24 is represented by a function with time as a parameter, the movement path of the machining reference point 24 is generated by integrating the function with respect to time.

[0031] The trajectory may include information specifying the pressure acting from the grindstone 22 to the target material 80 at the processing reference point 24 at each position on the movement path of the processing reference point 24. The pressure acting from the grindstone 22 to the target material 80 may be represented by a function with time as a parameter.

[0032] The control device 12 may generate a trajectory such that at least one of the moving speed of the grinding tool relative to the target material 80 and the pressure applied from the grinding tool to the target material 80 changes according to the position of the grinding tool. The control device 12 may generate a trajectory such that both the moving speed of the grinding tool relative to the target material 80 and the pressure applied from the grinding tool to the target material 80 change according to the position of the grinding tool. The faster the moving speed of the grinding tool, the shorter the time the grinding tool stays at that position. Therefore, the faster the moving speed of the grinding tool, the less the grinding amount at that position. Also, the smaller the pressure applied from the grinding tool to the target material 80, the less the grinding amount at that position. The control device 12 can control the grinding amount at each position by controlling at least one of the moving speed of the grinding tool or the pressure applied at each position. The control device 12 can reduce steps in the ground portion by controlling at least one of the moving speed of the grinding tool or the pressure applied at each position so that the grinding amount changes smoothly.

[0033] The trajectory may include information specifying the orientation of the grindstone 22 at each position on the movement path of the machining reference point 24. The orientation of the grindstone 22 may be expressed as the angle of the grindstone 22 with respect to a tangent to the trajectory at each position.

[0034] The control device 12 may generate the movement path of the machining reference point 24 to include a path 41 along a grinding surface 84, as exemplified in FIG. 4. The grinding surface 84 is assumed to be a part of the surface of the target material 80. The solid line representing the grinding surface 84 in FIG. 4 corresponds to a line where a cross section including the feed direction of the grinding tool intersects with the grinding surface 84. The cross section including the feed direction of the grinding tool may be a plane or a curved surface. When the cross section including the feed direction of the grinding tool is a plane, the path 41 is expressed as a two-dimensional curve. When the cross section including the feed direction of the grinding tool is a curved surface, the path 41 is expressed as a three-dimensional curve.

[0035] The path 41 is represented as a line connecting P(t), which is the position of the machining reference point 24 at time t. The time when the machining reference point 24 comes into contact with the grinding surface 84 and grinding starts is represented as t0. The position P(t0) of the machining reference point 24 at time t0 is represented as P0. The time when the machining reference point 24 leaves the grinding surface 84 and grinding ends is represented as t N At time t N Position P(t N ) is P N From time t0 to t N Each time between t1 and t N-1 Let the time from t1 to t N-1 The positions P(t1) to P(t N-1 ) are P1 to P N-1 Let the time from t1 to t N-1 Any time t i Position P(t i ) is P i Let it be expressed as follows.

[0036] The control device 12 may generate a trajectory such that the path 42 along which the machining reference point 24 moves until it comes into contact with the grinding surface 84 of the target material 80 before grinding starts is included in the movement path of the machining reference point 24. As illustrated in FIG. 5, the control device 12 calculates an angle θ with respect to a tangent 85 at P0, which is the point where the machining reference point 24 starts to come into contact with the grinding surface 84. s The path 42 may be generated so that the machining reference point 24 approaches along a line that forms an angle represented by θ s θ is also referred to as the approach angle and may be set to be greater than or equal to 0 degrees and less than or equal to 30 degrees. s By setting the angle to 30 degrees or less, steps are less likely to remain on the surface of the target material 80 after grinding.

[0037] The start point of the path 42 is the entry start point P s0 The end point of the path 42 is P0, which is the point where the machining reference point 24 starts to contact the grinding surface 84, and the grinding start point Ps Also expressed as the starting point of approach P s0 and grinding start point P s The distance between the target material 80 and the grindstone 22 may be appropriately set so that the target material 80 and the grindstone 22 do not come into contact with each other unintentionally. s0 Grinding start point P s The feed rate of the grinding tool when moving to the entry speed V s Let it be expressed as:

[0038] The control device 12 may generate a trajectory to specify the posture of the grindstone 22. The posture of the grindstone 22 may be specified by an angle between a plane perpendicular to the rotation axis 22a of the grindstone 22 and the traveling direction of the grindstone 22. The angle between the plane perpendicular to the rotation axis 22a of the grindstone 22 and the traveling direction of the grindstone 22 is represented by θ t The control device 12 controls the angle θ t The control device 12 generates a trajectory so as to maintain the angle θ of the grindstone 22 at the same value even after the machining reference point 24 enters the path 41. t A trajectory may be generated such that the vector θ changes at each point on the path 41.

[0039] The control device 12 may generate a trajectory so that a path 43 along which the machining reference point 24 moves when it leaves the grinding surface 84 of the target material 80 after grinding is completed is included in the movement path of the machining reference point 24. As illustrated in FIG. 6, the control device 12 determines whether the machining reference point 24 starts to leave the grinding surface 84 at P N θ to the tangent line 86 at e The path 43 may be generated so that the machining reference point 24 departs along a line that forms an angle represented by θ s is also referred to as the take-off angle and may be set to 20 degrees or more.

[0040] The starting point of the path 43 is the end point P of the path 41 for grinding the grinding surface 84. N The grinding end point P e The end point of the path 43 is the point where the removal of the grinding tool is completed, and P e0 The grinding end point P e and the departure completion point Pe0 The distance between the grinding end point P and the grindstone 22 may be appropriately set so that the target material 80 and the grindstone 22 do not come into contact with each other unintentionally. e From the departure completion point P e0 The feed rate of the grinding tool when moving to the release speed V e Let it be expressed as:

[0041] The attitude of the grinding wheel 22 when the grinding tool leaves the grinding surface 84 may be specified by the angle between a plane perpendicular to the rotation axis 22a of the grinding wheel 22 and the moving direction of the grinding wheel 22. The angle between the plane perpendicular to the rotation axis 22a of the grinding wheel 22 and the moving direction of the grinding wheel 22 is represented by θ t The angle at which the grinding wheel 22 leaves the grinding surface 84 may be the same as the angle at which the grinding wheel 22 enters the grinding surface 84, or may be a different value.

[0042] The control device 12 specifies the moving speed of the machining reference point 24 of the grindstone 22 at each time so as to move the machining reference point 24 along the path 41. The control device 12 generates a trajectory including information on the moving speed of the machining reference point 24 at each time. The moving speed of the machining reference point 24 is also called a grinding speed. In FIG. 4, N The magnitude of the grinding speed at each time from V0 to V N In other words, P0 to P N The magnitude of the grinding speed at each position is V0 to V N Let P0 to P N The direction of the grinding speed at each position up to the end point coincides with the tangent direction of the grinding surface 84 at each position.

[0043] The control device 12 generates a trajectory so as to include information specifying the pressure acting from the grinding wheel 22 on the grinding surface 84 at the processing reference point 24 at each time (at each position). The pressure acting from the grinding wheel 22 on the grinding surface 84 at the processing reference point 24 is also referred to as a grinding pressure. N The magnitude of the grinding pressure at each time from F0 to F NIn other words, P0 to P N The magnitude of the grinding pressure at each position is F0 to F N It is expressed from P0 to P N The direction of the grinding pressure at each position up to coincide with the normal direction of the grinding surface 84 at each position.

[0044] The control device 12 operates the grinding device 10 based on the generated trajectory. The control device 12 uses the pressure measuring device 14 to measure the grinding pressure acting from the grinding wheel 22 on the target material 80 when the grinding wheel 22 comes into contact with the target material 80 to grind and remove the removal target 82. The control device 12 operates the grinding device 10 so that the measured value of the grinding pressure measured by the pressure measuring device 14 approaches the grinding pressure at each position specified by the trajectory. Specifically, the control device 12 operates the grinding device 10 so as to move the grinding wheel 22 away from the surface of the target material 80 when the measured value of the grinding pressure is greater than the grinding pressure specified by the trajectory. The control device 12 operates the grinding device 10 so as to press the grinding wheel 22 against the surface of the target material 80 when the measured value of the grinding pressure is less than the grinding pressure specified by the trajectory.

[0045] The shape measuring device 32 measures the shape of the target material 80 after grinding for a predetermined time or grinding by a predetermined amount. The removal target recognition device 30 recognizes the removal target 82 based on the data of the three-dimensional shape of the surface of the target material 80 after grinding. The control device 12 determines whether the removal of the removal target 82 has been completed or whether the removal target 82 still remains based on the recognition result of the removal target 82. If the removal target 82 still remains, the control device 12 regenerates a trajectory based on the data of the three-dimensional shape of the surface of the target material 80 and operates the grinding device 10 to perform the grinding again. If the removal of the removal target 82 has been completed, the control device 12 ends the grinding.

[0046] The control device 12 controls the grinding speed V0 to V N4, may be set to a large value near the start or end point of the path 41 and a small value near the center of the path 41. The control device 12 may change the grinding speed at each position, for example, as shown in a graph in FIG. 7. The horizontal axis of the graph in FIG. 7 represents each of the positions P0 to P1 on the path 41. N and approach starting point P s0 and withdrawal completion point P e0 The vertical axis represents the grinding speed V. In the graph of FIG. 7, the grinding speed V is i Grinding speed at V i is the minimum value V min It is set so that:

[0047] The control device 12 controls the grinding pressure F0 to F N 4, the magnitude of the grinding pressure may be set to a small value at the start or end point of the path 41 and set to a large value near the center of the path 41. The control device 12 may change the grinding pressure at each position, for example, as shown in a graph in FIG. 8. The horizontal axis of the graph in FIG. 8 represents the grinding pressure at each of the positions P0 to P N and approach starting point P s0 and withdrawal completion point P e0 The vertical axis represents the grinding pressure F. In the graph of FIG. 8, the grinding pressure F is i Grinding pressure F i is the maximum value F max The position where the grinding speed is at its minimum value and the position where the grinding pressure is at its maximum value may be the same or different from each other.

[0048] The control device 12 can reduce the step occurring at the boundary between the ground portion, which is the portion to be ground, and the unground portion, which is the portion not to be ground, by operating the grinding device 10 using a trajectory in which the grinding speed and grinding pressure are set as described above. The control device 12 may also generate a trajectory such that the attitude of the grinding wheel 22, the grinding speed, or the grinding pressure changes continuously while moving the grinding wheel 22 along the path 41. The control device 12 can minimize the step occurring at the boundary between the ground portion and the unground portion while removing the removal target 82 by operating the grinding device 10 using the trajectory generated in this manner.

[0049] The graph of the grinding speed V illustrated in FIG. 7 may be a graph of a fourth-order equation of the position P, expressed as the following equation (1).

number

[0050] The graph of the grinding pressure F illustrated in FIG. 8 may be a graph of a fourth-order equation of the position P, which is expressed as the following equation (2).

number

[0051] As exemplified by equations (1) and (2), by expressing the grinding speed and grinding pressure as a quartic equation for the position P, the control device 12 can set nine parameters in each equation. In this way, the control device 12 can precisely set the target values ​​of the grinding speed and grinding pressure in accordance with the grinding conditions. Also, by expressing the grinding speed and grinding pressure as a quartic equation for the position P, the control device 12 can set the path 41 of the grinding tool as a smooth, continuous straight line or curve. Also, the grinding start point P s In this case, the grinding speed is the grinding tool entry speed V s By smoothly and continuously changing the grinding speed from to V(P), the step at the boundary between the ground and unground areas is reduced. e In this case, the grinding speed V(P) is the removal speed V e The smooth, continuous change in surface roughness reduces the step at the boundary between ground and unground portions.

[0052] The control device 12 may set the following equation (3) as an equation expressing the grinding speed V.

number

[0053] The control device 12 may set the following formula (4) as a formula expressing the grinding pressure F.

number

[0054] As exemplified by the formulas (3) and (4), by expressing the grinding speed and the grinding pressure as sine functions having the position P as a parameter, the control device 12 can set the path 41 of the grinding tool as a smooth and continuous straight line or curve. s and grinding end point P e In the present invention, the smooth and continuous change in grinding speed reduces the step at the boundary between the ground and unground portions.

[0055] The control device 12 may express the grinding speed by a mathematical expression including at least one of a fourth-order expression of the position P or a sine function having the position P as a parameter. The control device 12 may express the grinding pressure by a mathematical expression including at least one of a fourth-order expression of the position P or a sine function having the position P as a parameter. The control device 12 may express the grinding speed or the grinding pressure by a mathematical expression including at least a part of the mathematical expression of various other smooth continuous functions such as a Gaussian distribution equation.

[0056] V(P), a function representing the grinding speed, is also referred to as a speed function. F(P), a function representing the grinding pressure, is also referred to as a pressure function. The control device 12 may generate a trajectory such that the absolute value of the function obtained by first-order differentiation of the speed function with respect to the position P of the grinding tool is less than the velocity first-order differential threshold. In this way, a sudden change in the grinding speed is avoided. The control device 12 may generate a trajectory such that the absolute value of the function obtained by first-order differentiation of the pressure function with respect to the position P of the grinding tool is less than the pressure first-order differential threshold. In this way, a sudden change in the grinding pressure is avoided. By avoiding a sudden change in the grinding speed and the grinding pressure, the step in the surface shape of the target material 80 after grinding is reduced.

[0057] The control device 12 may generate a trajectory such that the function obtained by second-order differentiation of the velocity function at the position P of the grinding tool and the function obtained by second-order differentiation of the pressure function at the position P of the grinding tool are continuous functions. In this way, the grinding speed and the grinding pressure change smoothly. As a result, the step of the surface shape of the target material 80 after grinding is reduced. In addition, the control device 12 may generate a trajectory such that the absolute value of the function obtained by second-order differentiation of the velocity function at the position P of the grinding tool is less than the velocity second-order differentiation threshold. In this way, the curvature at the minimum value of the graph of the grinding speed is reduced. In addition, the control device 12 may generate a trajectory such that the absolute value of the function obtained by second-order differentiation of the pressure function at the position P of the grinding tool is less than the pressure second-order differentiation threshold. In this way, the curvature at the maximum value of the graph of the grinding pressure is reduced. By reducing the curvature of the graphs of the grinding speed and the grinding pressure, the grinding part of the target material 80 does not become suddenly deep.

[0058] The control device 12 may generate a trajectory such that the speed function has a minimum value at at least one position and the pressure function has a maximum value at at least one position. In this way, the grinding speed and the grinding pressure do not change monotonically. As a result, the steps are reduced at the start and end of grinding.

[0059] At least a part of the velocity function and the pressure function may be expressed by an even function with the origin at a position included in the range in which the target material 80 is ground. For example, in the graph of FIG. 7, the graph of the velocity function V(P) is expressed by an even function with the origin at a position P included in the range in which the target material 80 is ground. i Therefore, the velocity function V(P) in the graph of Figure 7 is P i 8, the pressure function F(P) is an even function with its origin at a position P i Therefore, the pressure function F(P) in the graph of FIG. i is an even function with the origin at . By making at least a part of the velocity function and the pressure function an even function, the shapes of the start side and the end side of grinding become symmetrical. As a result, the quality of the ground portion is improved.

[0060] <Flowchart> The grinding system 1 may execute a product manufacturing method including the steps of the flowchart illustrated in Fig. 9. The product manufacturing method may include a trajectory generation method for the control device 12 of the grinding system 1 to generate a grinding trajectory. The product manufacturing method or the trajectory generation method may be realized as a product manufacturing program or a trajectory generation program executed by a processor included in the control device 12 or the like of the grinding system 1. The product manufacturing program or the trajectory generation program may be stored in a non-transitory computer-readable medium.

[0061] The shape measuring device 32 measures the shape of the target material 80 to be ground (step S1). The removal target recognizing device 30 recognizes the removal target 82 included in the target material 80 based on the shape data of the target material 80 (step S2).

[0062] The control device 12 generates a grinding trajectory for the grinding device 10 based on the measurement data of the shape of the target material 80 and the recognition result of the removal target 82 (step S3). The control device 12 drives the grinding device 10 based on the generated trajectory (step S4). The control device 12 acquires the measurement result of the grinding pressure from the pressure measuring device 14, and controls the grinding device 10 so that the measured value of the grinding pressure approaches the grinding pressure specified by the trajectory (step S5). The control device 12 determines whether grinding is completed (step S6). For example, the control device 12 may move the grinding device 10 to the separation completion point P e0 When the grinding is not completed (step S6: NO), the control device 12 returns to the procedure of step S4 and continues driving the grinding device 10 until grinding is completed. When the grinding is completed (step S6: YES), the control device 12 ends the execution of the procedure of the flowchart in FIG. 9. As a product manufacturing method, the grinding system 1 may further execute a step of inspecting whether the removal target 82 has been removed after grinding is completed. A trajectory generating method of the product manufacturing method may include the procedures of steps S1 to S3 in FIG. 9.

[0063] 9, steps S1, S2, and S3 are steps for generating a path. The grinding system 1 may execute the steps including steps S1, S2, and S3 as a path generating method.

[0064] As described above, according to the grinding system 1 and the grinding method of the present disclosure, the grinding device 10 is operated using a trajectory in which the grinding speed and the grinding pressure are set, thereby reducing the step occurring at the boundary between the ground portion and the unground portion. Furthermore, the control device 12 may generate a trajectory such that the attitude of the grinding wheel 22, the grinding speed, or the grinding pressure changes continuously while moving the grinding wheel 22 along the path 41. By operating the grinding device 10 using the trajectory generated in this manner, the control device 12 can minimize the step occurring at the boundary between the ground portion and the unground portion while removing the removal target 82.

[0065] (Example) In the embodiment, the control device 12 generates a trajectory so as to set the grinding speed by equation (1) and the grinding pressure by equation (2). The control device 12 sets the coefficients of equations (1) and (2) to the following values. These coefficients may be changed as appropriate depending on the size of the object to be removed 82 or the material of the object to be ground 80. In the embodiment, the coefficients are set so that the grinding speed V is the slowest and the grinding pressure F is the greatest near the center of the path 41 for grinding the object to be removed 82. a v1 =-2000, a v2 =(P e -P s ) / 2 b v1 =0, b v2 =-(P e -P s ) / 2 c v1 =1000, c v2 =-(P e -P s ) / 2 d v1 =0, d v2 =-(P e -P s ) / 2 ev =V min =10 a f1 =1800, a f2 =-(P e -P s ) / 2 b f1 =0, b f2 =(P e -P s ) / 2 c f1 =-900, c f2 =(P e -P s ) / 2 d f1 =0, d f2 =(P e -P s ) / 2 e f =F max =150

[0066] Moreover, equations (1) and (2) are expressed as the starting point of grinding P s and grinding end point P e The following boundary conditions are satisfied in V(P s ) / ∂P=0, V(P e ) / ∂P=0 F(P s ) / ∂P=0, F(P e ) / ∂P=0

[0067] FIG. 10 shows the solid line graph of the measurement results of the surface shape of the target material 80 after grinding as the grinding depth when the target material 80 is ground under the above-mentioned conditions. The horizontal axis of the graph in FIG. 10 represents the position in the feed direction of the grinding tool. The vertical axis represents the grinding depth at each position. In this embodiment, the grinding depth changes smoothly and gently with respect to the change in position in the feed direction. The smooth and gentle change in the grinding depth reduces steps. In addition, the grinding depth exceeds the target value. As a result, regrinding is not required.

[0068] On the other hand, a method of grinding without changing the grinding speed and grinding pressure can be considered as a method of comparison. The results of measuring the surface shape of the target material ground by the method of comparison as the grinding depth are shown in the dashed graph in Figure 10. In the results of grinding by the method of comparison, there are parts where the grinding depth changes sharply with the change in position in the feed direction, especially near the grinding start point and grinding end point. Such sharply changing parts are judged to be steps by a sensory inspection using the inspector's sense of touch, etc. As a result, re-grinding of the parts judged to be steps is required.

[0069] As described above, according to the grinding method of this embodiment, the quality of the ground portion is improved compared to the method of the comparative example. In addition, the rate at which the ground portion needs to be re-ground is reduced. Specifically, under the conditions of the above-mentioned example, the rate at which re-grounding was required was reduced by about 90%. As a result, the overall grinding work by the grinding device 10 was reduced by about 40%.

[0070] Although the embodiments of the present disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art can make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications or alterations are included in the scope of the present disclosure. For example, the functions included in each component or each step can be rearranged so as not to be logically inconsistent, and multiple components or steps can be combined into one or divided. The embodiments of the present disclosure can also be realized as a program executed by a processor included in the device or a storage medium on which a program is recorded. It should be understood that these are also included in the scope of the present disclosure. [Explanation of symbols]

[0071] 1 Grinding System 10 Grinding equipment 12 Control device 14 Pressure measuring device 20 Grinder 22 Grindstone (22a: Rotating axis, 24: Processing reference point) 30 Removal target recognition device 32 Shape measuring device Routes 41, 42, and 43 80 Target material (82: removal target, 84: grinding surface, 85, 86: tangent line)

Claims

1. A grinding device including a grinding tool for grinding a target material; a grinding pressure measuring device for measuring a grinding pressure acting on the target material from the grinding tool; a control device that generates a trajectory including information specifying a movement path of the grinding tool for grinding the object to be removed based on a three-dimensional shape of the surface of the target material and a position and shape of a removal target of the target material, and information specifying at least one of a movement speed of the grinding tool and the grinding pressure with respect to the target material at each position on the movement path, and controls the grinding device so that the grinding tool moves based on the trajectory; Equipped with the control device generates the trajectory such that an absolute value of a function obtained by first-order differentiation of a velocity function representing the moving speed of the grinding tool with the position of the grinding tool as a parameter with respect to the position of the grinding tool is less than a velocity first-order differentiation threshold, or such that an absolute value of a function obtained by first-order differentiation of a pressure function representing the grinding pressure with the position of the grinding tool as a parameter with respect to the position of the grinding tool is less than a pressure first-order differentiation threshold. Grinding system.

2. The grinding system according to claim 1 , wherein the control device generates the trajectory such that both a moving speed of the grinding tool relative to the target material and the grinding pressure change depending on a position of the grinding tool.

3. The grinding system according to claim 2 , wherein the control device generates the trajectory such that an approach angle when the grinding tool contacts the target material is 30 degrees or less with respect to a tangent to the target material.

4. The control device generates the trajectory so that the absolute value of a function obtained by first differentiating the velocity function with respect to the position of the grinding tool is less than the velocity first differential threshold, and so that the absolute value of a function obtained by first differentiating the pressure function with respect to the position of the grinding tool is less than the pressure first differential threshold.

5. The grinding system according to claim 4 , wherein the control device generates the trajectory such that the velocity function has a minimum value at at least one position, and the pressure function has a maximum value at at least one position.

6. The grinding system according to claim 5 , wherein at least a part of the velocity function and the pressure function are expressed as even functions having an origin at a position included in a range in which the target material is ground.

7. The grinding system according to claim 6 , wherein at least a portion of the velocity function and the pressure function is expressed by any one of a fourth-order function, a sine function, or a Gaussian distribution function of the position of the grinding tool.

8. A trajectory generating method for generating a trajectory including information for specifying a moving path of a grinding tool for grinding a target material, and information for specifying at least one of a moving speed of the grinding tool with respect to the target material at each position on the moving path and a grinding pressure applied from the grinding tool to the target material, the method comprising: measuring a three-dimensional shape of a surface of the target material; Recognizing a position and a shape of a target to be removed from the target material; generating the trajectory based on the three-dimensional shape and orientation of the target material and the position and shape of the removal target such that an absolute value of a function obtained by first-order differentiation of a velocity function with the position of the grinding tool as a parameter and expressing the moving speed of the grinding tool with respect to the position of the grinding tool is less than a velocity first-order differentiation threshold, or such that an absolute value of a function obtained by first-order differentiation of a pressure function with the position of the grinding tool as a parameter and expressing the grinding pressure with respect to the position of the grinding tool is less than a pressure first-order differentiation threshold; A trajectory generation method comprising:

9. A method for manufacturing a product, comprising the step of controlling a grinding tool based on a path generated by executing the path generating method according to claim 8, and grinding a removal target of a target material.

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