Grinding system, trajectory generation method, and product manufacturing method

Abstract

A grinding system (1) is provided with: a grinding device (10) provided with a grinding tool (22) for grinding a material (80) to be ground; a pressurization force measuring device (14) that measures a grinding pressurization force acting on the target material (80) from the grinding tool (22); and a control device (12) that generates a trajectory of a grinding tool (22) for grinding the removal object (82) on the basis of the three-dimensional shape of the surface of the object material (80) and the position and shape of the removal object (82) of the object material (80), and controls the grinding device (10) such that the grinding tool (22) moves on the basis of the trajectory. The control device (12) generates a trajectory such that at least one of the speed of movement of the grinding tool (22) with respect to the target material (80) and the grinding pressure changes in accordance with the position of the grinding tool (22).

Description

Technical Field

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

[0002] For example, in the manufacturing process of steel products, surface defects are generated due to various factors during casting or rolling. The surface defects are removed by the operator grinding the defective part with a grinder. However, the grinding work using a grinder is accompanied by various risks such as the rotating body being very close to the operator, the operator being exposed to sparks, dust or noise, or the operator suffering from white finger disease due to vibration during grinding. There is a shortage of manpower to perform operations accompanied by risks. In addition, it is required to avoid operations accompanied by risks. From the perspective of labor saving and safety, it is required to automate the grinding work of defects.

[0003] Various methods have been proposed in the past as methods for automating the grinding operation of defects. In the existing methods, a step is generated at the boundary between the grinding part and the unground part of the object when grinding the defect, which is a problem. The step generated at the boundary between the grinding part and the unground part has an adverse effect on the appearance of the product. In addition, due to the step generated at the boundary between the grinding part and the unground part, the size of the product surface changes dramatically. The dramatic change in the size of the product surface sometimes causes the product to break when a large force is applied to the product or when the product is subjected to additional processing.

[0004] For example, Patent Document 1 discloses a method of changing the contact area of ​​a grinding wheel by periodically varying the contact angle during reciprocating motion of a grinder in the feed direction so that a step generated at the boundary between a ground portion and an unground portion becomes smaller.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 7-100759

[0006] Even in the method disclosed in Patent Document 1, a step is generated due to overshoot when the grinding wheel of the grinder contacts the object material to be ground or when the grinding wheel separates from the object material. When grinding is performed 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 contacts or separates, it is necessary to increase the response speed of the control system while reflecting the measurement results of the force sensor in the trajectory calculation of the grinding wheel. In this case, the cost of the control device or system becomes high. In addition, it takes a lot of time to adjust the control system in a manner that can cope with various steel grades or grinding conditions. Summary of the invention

[0007] An object of the present disclosure is to provide a grinding system, a trajectory generation method, and a product manufacturing method that can reduce steps generated when grinding a removal object of a three-dimensional grinding object material such as a steel product.

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

[0009] A trajectory generation method according to an embodiment of the present disclosure generates a trajectory for controlling a grinding tool of a grinding object material, and includes: a step of measuring a three-dimensional shape of the surface of the object material; a step of identifying the position and shape of the removal object of the object material; and a step of generating the trajectory such that at least one of the speed of the grinding tool relative to the object material or the grinding pressing force applied from the grinding tool to the object material changes according to the position of the grinding tool based on the three-dimensional shape and posture of the object material and the position and shape of the removal object.

[0010] A product manufacturing method according to an embodiment of the present disclosure includes the step of controlling a grinding tool based on a trajectory generated by executing the above trajectory generation method to grind a removal object of a grinding object material.

[0011] According to the grinding system, the trajectory generation method, and the product manufacturing method of the present disclosure, steps generated by grinding can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a diagram showing a structural example of the grinding system of the present disclosure.

[0013] Figure 2 is a side view showing an example of a grinding device.

[0014] Figure 3 is Figure 2 a view in the direction A of

[0015] Figure 4 is a diagram showing an example of a trajectory of a grinding tool when grinding an object.

[0016] Figure 5 This is a diagram showing an example of the trajectory when the grinding tool enters the object.

[0017] Figure 6 This is a diagram showing an example of the trajectory when the grinding tool detaches from the object.

[0018] Figure 7 This is a graph showing an example of the relationship between the position of the grinding tool and the speed of the grinding tool at each position.

[0019] Figure 8 This is a graph showing an example of the relationship between the position of the grinding tool and the grinding pressure at each position.

[0020] Figure 9 This is a flowchart showing an example of the process of the grinding method of the present embodiment.

[0021] Figure 10 This is a graph showing an example of the relationship between the position of the feed direction of the grinding tool obtained by the grinding method of the present embodiment and the grinding depth of the object at each position. Detailed Embodiment

[0022] Hereinafter, embodiments of the grinding system, trajectory generation method, and product manufacturing method of the present disclosure will be described based on the accompanying drawings. Each drawing is schematic, and there are cases different from reality. In addition, the following embodiments illustrate devices or methods for embodying the technical idea of the present disclosure, and do not specify the structure as the following content. That is, the technical idea of the present disclosure can be variously modified within the technical scope described in the claims.

[0023] (Structural Example of Grinding System 1)

[0024] As Figure 1 shown, a grinding system 1 according to an embodiment of the present disclosure includes: a grinding device 10, a control device 12, a pressure measurement device 14, a shape measurement device 32, and a removal object recognition device 30. The grinding system 1 grinds the object material 80 to be ground by the grinding device 10 and removes the removal object 82 contained in the object material 80. Hereinafter, an example of each structural part of the grinding system 1 will be described.

[0025] <Grinding Device 10>

[0026] As Figure 1 , Figure 2 and Figure 3 shown, 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 disc shape. The grinder 20 rotates the grinding wheel 22 at a speed Figure 3Rotates about an axis perpendicular to the paper surface of []. The point where the grinding wheel 22 contacts the object material 80 is also referred to as the machining reference point 24. The grinding device 10 grinds the surface of the object material 80 at the machining reference point 24. The grinding device 10 can grind the surface of the object material 80 into a planar shape by moving the machining reference point 24 while grinding the surface of the object material 80. The grinding device 10 controls the posture of the grinding wheel 22 such that the feed direction of the machining reference point 24 with respect to the grinding wheel 22 is located behind the grinding wheel 22. In other words, the grinding device 10 controls the posture of the grinding wheel 22 such that the angle formed by the surface of the grinding wheel 22 parallel to the paper surface of [] and the feed direction of the grinding wheel 22 is an acute angle. Figure 3 The angle formed by the surface of the grinding wheel 22 parallel to the paper surface of [] and the feed direction of the grinding wheel 22 is an acute angle.

[0027] The grinding wheel 22 and the grinding machine 20 are also referred to as grinding tools. The grinding device 10 includes a grinding tool. The grinding tool is not limited to a structure formed by combining the grinding wheel 22 and the grinding machine 20. As long as it can grind the object material 80, the grinding tool can also be configured to include devices with various other structures or shapes.

[0028] The grinding device 10 includes a moving mechanism for the grinding tool so as to be able to control the position of the machining reference point 24 and the posture of the grinding tool at the machining reference point 24. The grinding device 10 can be configured to include an articulated robot as the moving mechanism for the grinding tool. The grinding tool can be provided at the front end or midway of the articulated robot. The articulated robot can be configured as a multi-axis robot, for example. The multi-axis robot can be configured to have 6 axes (rotation axes), for example, and has degrees of freedom in 6-axis directions. The multi-axis robot can be configured to have at least 3-axis directions of moving degrees of freedom. The multi-axis robot can be a vertically articulated robot.

[0029] The moving mechanism for the grinding tool is not limited to an articulated robot. As long as it can control the position of the machining reference point 24 and the posture of the grinding tool at the machining reference point 24, the moving mechanism for the grinding tool can be configured to include devices with various other structures or shapes.

[0030] <Control device 12>

[0031] The control device 12 controls the grinding device 10 in such a way as to grind and remove the removal object 82 included in the surface of the removal object material 80, based on the information acquired from the shape measurement device 32, the removal object recognition device 30, or the pressing force measurement device 14. The control device 12 may also control the shape measurement device 32, the removal object recognition device 30, or the pressing force measurement device 14. For example, 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 be able to control each part of the grinding system 1. The control device 12 may be constituted by one processor or may be constituted by a plurality of processors. The processor constituting the control device 12 can control each structural part of the grinding system 1 by reading and executing a program stored in a storage unit described later.

[0032] The control device 12 may include a storage unit. The storage unit stores various information, data, etc. For example, the storage unit may store a program executed in the control device 12, or data or processing results used in the processing executed in the control device 12. In addition, the storage unit may function as a working memory of the control device 12. For example, the storage unit may be configured to include a semiconductor memory or the like, but is not limited thereto. For example, the storage unit may also be configured to be used as an internal memory of the processor of the control device 12, and may also be configured to be a hard disk drive (HDD) accessible from the control device 12. The storage unit may be configured to be a non-transitory readable medium. The storage unit may be integrally formed with the control device 12 or may be separately formed from the control device 12.

[0033] The control device 12 may include a communication unit. The communication unit may be configured to include a communication interface for communicating with each structural part of the grinding system 1 such as the grinding device 10, the shape measurement device 32, the removal object recognition device 30, or the pressing force measurement device 14 by wire or wirelessly. The communication interface may also be configured to be able to communicate with other devices. The communication unit may be configured to include an input / output port for inputting / outputting data between each structural part of the grinding system 1 or other devices. The communication unit may transmit and receive required data and signals between each structural part 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 communication standards for cellular phones 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 / output data based on various standards.

[0034] <Pressure Measuring Device 14>

[0035] The pressure measuring device 14 measures the pressure applied from the grinding tool to the object material 80 when grinding the object material 80 with the grinding tool. The pressure applied from the grinding tool to the object material 80 balances the reaction force applied from the object material 80 to the grinding tool. The pressure measuring device 14 can be configured to include various sensors such as a torque sensor or a pressure sensor, for example.

[0036] <Shape Measuring Device 32>

[0037] The shape measuring device 32 measures the three-dimensional shape of the surface of the object material 80 to be ground. The shape measuring device 32 can be configured to include a camera that photographs the object material 80. The shape measuring device 32 can output the image obtained by photographing the object material 80 as the measurement result of the three-dimensional shape of the surface of the object material 80.

[0038] The shape measuring device 32 can calculate the three-dimensional shape of the surface of the object material 80 as a set of three-dimensional coordinates of each point on the surface of the object material 80, that is, point cloud information, and output the point cloud information as the measurement result of the three-dimensional shape of the surface of the object material 80. The shape measuring device 32 can be configured to include, for example, a depth camera that measures the distance to each point on the surface of the object material 80. The shape measuring device 32 can measure the three-dimensional coordinates of each point on the surface of the object material 80 based on the measurement result of the depth camera. The shape measuring device 32 can be configured to measure the three-dimensional coordinates of each point on the surface of the object material 80 by bringing a detector into contact with the surface of the object material 80, for example. The shape measuring device 32 can be configured to measure the three-dimensional coordinates of each point on the surface of the object material 80 by irradiating the object material 80 with laser light or the like and detecting the reflected light, for example.

[0039] <Removal Object Recognition Device 30>

[0040] The removal object recognition device 30 identifies the position and shape of the removal object 82 that is to be removed on the surface of the object material 80 based on the measurement result of the three-dimensional shape of the surface of the object material 80. The removal object 82 can include, for example, a convex portion generated on the surface of the object material 80. The removal object recognition device 30 can identify the position and shape of the removal object 82 included as a convex portion on the surface of the object material 80 by comparing the measurement result of the three-dimensional shape of the surface of the object material 80 with the data of the normal three-dimensional shape. The removal object 82 can include, for example, a concave portion generated on the surface of the object material 80. The removal object 82 can include surface defects such as dirt or rust that do not change the shape of the surface of the object material 80. The removal object 82 is not limited to the above examples and can include various parts of the object material 80 that need to be removed.

[0041] The removal object recognition device 30 may also be configured as part of the control device 12. In other words, the control device 12 may obtain data on the three-dimensional shape of the surface of the object material 80 from the shape measurement device 32 to identify the position and shape of the removal object 82.

[0042] (Operation example of the grinding system 1)

[0043] In the grinding system 1, the shape measurement device 32 measures the three-dimensional shape of the surface of the object material 80 to be ground. The measurement data of the three-dimensional shape of the surface of the object material 80 may include the size or posture of the object material 80, etc. The measurement data of the three-dimensional shape of the surface of the object material 80 may also be obtained as an image. The removal object recognition device 30 identifies the removal object 82 included in the surface of the object material 80 based on the measurement data of the three-dimensional shape of the surface of the object material 80. The removal object recognition device 30 may identify the position, or shape or size of the removal object 82. The control device 12 controls the grinding device 10 based on the recognition result of the removal object 82 so as to grind and remove the removal object 82 with the grinding tool. Hereinafter, an operation example of the grinding system 1 will be described. The removal object 82 is a convex portion generated on the surface of the object material 80.

[0044] In order to remove the removal object 82 included in the surface of the object material 80, the control device 12 may operate the grinding device 10 to grind the surface of the object material 80 for a specified time. The control device 12 may operate the grinding device 10 to grind the surface of the object material 80 by a specified grinding amount.

[0045] Specifically, the control device 12 performs inverse kinematics calculation based on the position and shape or size of the removal object 82 identified by the removal object recognition device 30, and generates a trajectory for operating the grinding device 10 to grind the removal object 82 by bringing the grinding wheel 22 into contact with the position of the removal object 82. The control device 12 controls the grinding device 10 to move the grinding tool based on the generated trajectory.

[0046] The trajectory includes information for determining the movement path of the machining reference point 24 of the grinding wheel 22. The trajectory may determine the movement path of the machining reference point 24 by including information on 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.

[0047] The locus may include information on the pressure applied by the grinding wheel 22 to the object material 80 at each position on the movement path of the machining reference point 24. The pressure applied by the grinding wheel 22 to the object material 80 can be represented by a function with time as a parameter.

[0048] The control device 12 can generate a locus in such a way that at least one of the moving speed of the grinding tool relative to the object material 80 or the pressure applied by the grinding tool to the object material 80 varies according to the position of the grinding tool. The control device 12 can also generate a locus in such a way that both the moving speed of the grinding tool relative to the object material 80 and the pressure applied by the grinding tool to the object material 80 vary 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. In addition, the smaller the pressure applied by the grinding tool to the object 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 or the pressure of the grinding tool at each position. The control device 12 can reduce the step of the ground part by controlling at least one of the moving speed or the pressure of the grinding tool in such a way that the grinding amount changes smoothly.

[0049] The locus may also include information on the posture of the grinding wheel 22 at each position on the movement path of the machining reference point 24. The posture of the grinding wheel 22 can be expressed as the angle of the grinding wheel 22 relative to the tangent of the locus at each position.

[0050] As Figure 4 illustrated, the control device 12 can generate the movement path of the machining reference point 24 in a way that includes the path 41 along the grinding surface 84. The grinding surface 84 is a part of the surface of the object material 80. In Figure 4 the solid line indicating the grinding surface 84 corresponds to the line where the cross-section of the grinding tool including the feed direction intersects the grinding surface 84. The cross-section of the grinding tool including the feed direction can be a plane or a curved surface. When the cross-section of the grinding tool including the feed direction is a plane, the path 41 is represented as a two-dimensional curve. When the cross-section of the grinding tool including the feed direction is a curved surface, the path 41 is represented as a three-dimensional curve.

[0051] The path 41 is represented as a line connecting the position of the machining reference point 24 at time t, that is, P(t). The time when the machining reference point 24 comes into contact with the grinding surface 84 and starts grinding is represented by 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 detaches from the grinding surface 84 and ends grinding is represented by t N is represented. The position P(t N of the machining reference point 24 at time tN ) is represented as P N . From time t0 to t N The respective times between are represented by t1 to t N-1 . From time t1 to t N-1 The positions P(t1) to P(t N-1 ) of the machining reference point 24 at each time are represented by P1 to P N-1 respectively. At any time t N-1 from time t1 to t i the position P(t i ) of the machining reference point 24 is represented by P i .

[0052] The control device 12 can generate a trajectory in such a manner that the path 42 that moves to contact the grinding surface 84 of the machining reference point 24 and the object material 80 before the start of grinding is included in the movement path of the machining reference point 24. As Figure 5 illustrated, the control device 12 can generate the path 42 in such a manner that the machining reference point 24 enters along a line that forms an angle represented by θ s with respect to the tangent line 85 at the point where the machining reference point 24 starts to contact the grinding surface 84, that is, P0. θ s is also referred to as the entry angle and can be set to 0 degrees or more and 30 degrees or less. By setting θ s to 30 degrees or less, steps are less likely to remain on the surface of the object material 80 after grinding.

[0053] The start point of the path 42 is represented as the entry start point P s0 where the grinding tool starts to enter. The end point of the path 42 is the point where the machining reference point 24 starts to contact the grinding surface 84, that is, P0, and is also represented as the grinding start point P s . The entry start point P s0 and the grinding start point P s The distance can be appropriately set so that the object material 80 and the grinding wheel 22 do not accidentally come into contact. The machining reference point 24 moves from the entry start point P s0 to the grinding start point P s The feed speed of the grinding tool at this time is represented as the entry speed V s .

[0054] The control device 12 can generate a trajectory in such a manner as to determine the posture of the grinding wheel 22. The posture of the grinding wheel 22 can be determined by the angle formed by the surface orthogonal to the rotation axis 22a of the grinding wheel 22 and the traveling direction of the grinding wheel 22. The angle formed by the surface orthogonal to the rotation axis 22a of the grinding wheel 22 and the traveling direction of the grinding wheel 22 is represented by θ Figure 5 in t . The control device 12 sets the angle θ tGenerate a trajectory in such a way that the value remains the same even after the machining reference point 24 enters the path 41. The control device 12 can also generate a trajectory in such a way that the angle θ of the grinding wheel 22 t changes at each point on the path 41.

[0055] The control device 12 can generate a trajectory in such a way that the path 43 along which the machining reference point 24 moves when it separates from the grinding surface 84 of the object material 80 after grinding is included in the movement path of the machining reference point 24. As Figure 6 illustrated, the control device 12 can generate the path 43 in such a way that the machining reference point 24 moves along a line that forms an angle represented by θ N with respect to the tangent 86 at the point where the machining reference point 24 starts to separate from the grinding surface 84, that is, point P e . θ s is also referred to as the separation angle and can be set to 20 degrees or more.

[0056] The starting point of the path 43 is the end point P of the path 41 that grinds the grinding surface 84 N , and is also expressed as the grinding end point P where the grinding tool starts to separate e . The end point of the path 43 is the point where the separation of the grinding tool is completed, and is also expressed as P e0 . The grinding end point P e and the separation completion point P e0 The distance between them can be appropriately set so that the object material 80 and the grinding wheel 22 do not accidentally come into contact. The machining reference point 24 moves from the grinding end point P e to the separation completion point P e0 The feed speed of the grinding tool at this time is expressed as the separation speed V e .

[0057] The posture of the grinding wheel 22 when it separates from the grinding surface 84 can be determined by the angle formed by the surface of the grinding wheel 22 that is orthogonal to the rotation axis 22a and the traveling direction of the grinding wheel 22. The angle formed by the surface of the grinding wheel 22 that is orthogonal to the rotation axis 22a and the traveling direction of the grinding wheel 22 is represented by θ Figure 6 in t . The angle of the grinding wheel 22 when it separates from the grinding surface 84 can be the same value as the angle when the grinding wheel 22 enters the grinding surface 84, or it can be a different value.

[0058] The control device 12 determines the moving speed of the machining reference point 24 at each moment in such a way that the machining reference point 24 of the grinding wheel 22 moves along the path 41. The control device 12 generates a trajectory in such a way that it includes information on the moving speed of the machining reference point 24 at each moment. The moving speed of the machining reference point 24 is also referred to as the grinding speed. In Figure 4 , from time t0 to time t NThe magnitudes of the grinding speeds at respective times are represented by V0 to V N respectively. In other words, from P0 to P N the magnitudes of the grinding speeds at respective positions are represented by V0 to V N respectively. From P0 to P N the directions of the grinding speeds at respective positions are consistent with the tangential directions of the grinding surface 84 at respective positions.

[0059] The control device 12 generates a trajectory in a manner that includes information for determining the pressing force applied from the grinding wheel 22 to the grinding surface 84 at the machining reference point 24 at respective times (at respective positions). The pressing force applied from the grinding wheel 22 to the grinding surface 84 at the machining reference point 24 is also referred to as the grinding pressing force. The magnitudes of the grinding pressing forces at respective times from time t0 to time t N are represented by F0 to F N respectively. In other words, from P0 to P N the magnitudes of the grinding pressing forces at respective positions are represented by F0 to F N respectively. From P0 to P N the directions of the grinding pressing forces at respective positions are consistent with the normal directions of the grinding surface 84 at respective positions.

[0060] The control device 12 operates the grinding device 10 based on the generated trajectory. The control device 12 measures the grinding pressing force applied from the grinding wheel 22 to the workpiece 80 when the grinding wheel 22 contacts the workpiece 80 to grind and remove the removal object 82, by means of the pressing force measuring device 14. The control device 12 operates the grinding device 10 such that the measured value of the grinding pressing force measured by the pressing force measuring device 14 is close to the grinding pressing force at respective positions determined by the trajectory. Specifically, when the measured value of the grinding pressing force is greater than the grinding pressing force determined by the trajectory, the control device 12 operates the grinding device 10 to move the grinding wheel 22 away from the surface of the workpiece 80. When the measured value of the grinding pressing force is less than the grinding pressing force determined by the trajectory, the control device 12 operates the grinding device 10 to bring the grinding wheel 22 into contact with the surface of the workpiece 80.

[0061] After grinding for a specified time or grinding a specified amount of material, the shape measuring device 32 measures the shape of the object material 80 after grinding. The removal object recognition device 30 identifies the removal object 82 based on the three-dimensional shape data of the surface of the object material 80 after grinding. The control device 12 determines whether the removal of the removal object 82 has been completed or whether there is still a removal object 82 remaining based on the recognition result of the removal object 82. When there is still a removal object 82 remaining, the control device 12 re-grinds by regenerating the trajectory based on the three-dimensional shape data of the surface of the object material 80 and operating the grinding device 10. When the removal of the removal object 82 is completed, the control device 12 ends the grinding.

[0062] The control device 12 can set the grinding speeds V0 to V N to be of a magnitude such that, as represented by the length of the arrow in Figure 4 , a larger value is set near the start or end of the path 41, and a smaller value is set near the center of the path 41. For example, the control device 12 can vary the grinding speed at each position as shown in the graph in Figure 7 . Figure 7 The horizontal axis of the graph in N represents each position P0 to P on the path 41 s0 and the entry start point P e0 and the exit completion point P Figure 7 . The vertical axis represents the grinding speed V. In the graph in i , the grinding speed V is set such that the grinding speed V i at position P min becomes the minimum value V

[0063] The control device 12 can set the grinding pressures F0 to F N to be of a magnitude such that, as represented by the length of the arrow in Figure 4 , a smaller value is set at the start or end of the path 41, and a larger value is set near the center of the path 41. For example, the control device 12 can vary the grinding pressure at each position as shown in the graph in Figure 8 . Figure 8 The horizontal axis of the graph in N represents each position P0 to P on the path 41 s0 and the entry start point P e0 and the exit completion point P Figure 8 . The vertical axis represents the grinding pressure F. In the graph in i , the grinding pressure F is set such that the grinding pressure F i at position P max becomes the maximum value F

[0064] The control device 12 operates the grinding device 10 by using the trajectory in which the grinding speed and the grinding pressure are set as described above, and can reduce the step generated at the boundary between the ground portion as the portion to be ground and the unground portion as the unground portion. In addition, the control device 12 can generate a trajectory such that the posture, the grinding speed, or the grinding pressure of the grinding wheel 22 continuously changes during the movement of the grinding wheel 22 along the path 41. By operating the grinding device 10 by using the trajectory generated in this way, the control device 12 can minimize the step generated at the boundary between the ground portion and the unground portion while removing the object 82 to be removed.

[0065] Figure 7 The illustrated graph of the grinding speed V may be a graph of a quartic equation of the position P expressed by the following formula (1).

[0066] [Equation 1]

[0067]

[0068] Each coefficient of the formula (1) can be set, for example, as a value within the range determined by the following inequalities.

[0069] -10000V min ≤a v1 ≤0

[0070] -(P e -P s ) / 2≤a v2 ≤(P e -P s ) / 2

[0071] -10000V min ≤b v1 ≤10000V min

[0072] -(P e -P s ) / 2≤b v2 ≤(P e -P s ) / 2

[0073] 0≤c v1 ≤10000V min

[0074] -(P e -P s ) / 2≤c v2 ≤(P e -P s ) / 2

[0075] -10000V min≤d v1 ≤10000V min

[0076] -(P e -P s ) / 2≤d v2 ≤(P e -P s ) / 2

[0077] e v =V min

[0078] Figure 8 The illustrated graph of the grinding pressure F can be a graph of a quartic equation of the position P expressed by the following formula (2).

[0079] [Formula 2]

[0080]

[0081] The coefficients of formula (2) can be set, for example, as values within the range determined by the following inequalities.

[0082] 0≤a f1 ≤10000F max

[0083] -(P e -P s ) / 2≤a f2 ≤(P e -P s ) / 2

[0084] -10000F max ≤b f1 ≤10000F max

[0085] -(P e -P s ) / 2≤b f2 ≤(P e -P s ) / 2

[0086] 0≤c f1 ≤10000F max

[0087] -(P e -P s ) / 2≤c f2 ≤(P e -P s ) / 2

[0088] -10000F max ≤d f1≤10000F max

[0089] -(P e -P s ) / 2 ≤ d f2 ≤(P e -P s ) / 2

[0090] e f =F max

[0091] As exemplified by Formula (1) and Formula (2), by expressing the grinding speed and the grinding pressure with a quartic equation of the position P, the control device 12 can set 9 parameters in each formula. Accordingly, the control device 12 can finely set the target values of the grinding speed and the grinding pressure according to the grinding conditions. In addition, by expressing the grinding speed and the grinding pressure with a quartic equation of the position P, the control device 12 can set the path 41 of the grinding tool as a smooth and continuous straight line or curve. In addition, at the grinding start point P s , the grinding speed smoothly and continuously changes from the entering speed V of the grinding tool s to the grinding speed V(P), thereby reducing the step at the boundary between the ground portion and the unground portion. In addition, at the grinding end point P e , the grinding speed V(P) smoothly and continuously changes to the leaving speed V of the grinding tool e , thereby reducing the step at the boundary between the ground portion and the unground portion.

[0092] The control device 12 may also set the following Formula (3) as the formula representing the grinding speed V.

[0093] [Equation 3]

[0094]

[0095] The coefficients of Formula (3) can be set, for example, as values within the range determined by the following inequalities.

[0096] -10000V min ≤ a v1 ≤ 0, b v1 =V min + a v1 ,

[0097] The control device 12 may also set the following Formula (4) as the formula representing the grinding pressure F.

[0098] [Equation 4]

[0099]

[0100] Each coefficient of formula (4) can be set, for example, to a value within a range determined by the following inequalities.

[0101] 0 ≤ a f1 ≤ F max , b f1 = F max + a f1

[0102] As exemplified by formulas (3) and (4), by representing the grinding speed and the grinding pressure with a sine function having the position P as a parameter, the control device 12 can set the path 41 of the grinding tool to a smooth and continuous straight line or curve. In addition, at the grinding start point P s and the grinding end point P e , the grinding speed changes smoothly and continuously, thereby reducing the step at the boundary between the ground portion and the unground portion.

[0103] The control device 12 can represent the grinding speed with a mathematical expression including at least one of a quartic expression containing the position P or a sine function having the position P as a parameter. The control device 12 can represent the grinding pressure with a mathematical expression including at least one of a quartic expression containing the position P or a sine function having the position P as a parameter. The control device 12 can represent the grinding speed or the grinding pressure, for example, with a mathematical expression including a mathematical expression of at least a part of various other smooth and continuous functions such as a Gaussian distribution.

[0104] V(P), which is a function representing the grinding speed, is also called a speed function. F(P), which is a function representing the grinding pressure, is also called a pressure function. The control device 12 can generate a trajectory in such a way that the absolute value of the function obtained by differentiating the speed function with respect to the position P of the grinding tool is less than the speed first-order differential threshold. Accordingly, a sharp change in the grinding speed can be avoided. The control device 12 can generate a trajectory in such a way that the absolute value of the function obtained by differentiating the pressure function with respect to the position P of the grinding tool is less than the pressure first-order differential threshold. Accordingly, a sharp change in the grinding pressure can be avoided. By avoiding sharp changes in the grinding speed and the grinding pressure, the step of the surface shape of the object material 80 after grinding is reduced.

[0105] The control device 12 can generate a trajectory in such a way that the function obtained by second-order differentiating the speed function with respect to the position P of the grinding tool and the function obtained by second-order differentiating the pressure application function with respect to the position P of the grinding tool are each continuous functions. Accordingly, the grinding speed and the grinding pressure application smoothly change. As a result, the step of the surface shape of the object material 80 after grinding is reduced. In addition, the control device 12 can generate a trajectory in such a way that the absolute value of the function obtained by second-order differentiating the speed function with respect to the position P of the grinding tool is less than the speed second-order differentiation threshold. Accordingly, the curvature at the minimum value of the graph of the grinding speed is reduced. In addition, the control device 12 can generate a trajectory in such a way that the absolute value of the function obtained by second-order differentiating the pressure application function with respect to the position P of the grinding tool is less than the pressure application second-order differentiation threshold. Accordingly, the curvature at the maximum value of the graph of the grinding pressure application is reduced. By reducing the curvature of the graphs of the grinding speed and the grinding pressure application, the ground portion of the object material 80 does not become sharply deeper.

[0106] The control device 12 can generate a trajectory in such a way that the speed function becomes a minimum value at at least one position and the pressure application function becomes a maximum value at at least one position. Accordingly, the grinding speed and the grinding pressure application do not change monotonically. As a result, the steps are reduced on the start side and the end side of grinding, respectively.

[0107] At least a part of the speed function and the pressure application function can be represented by an even function with the position included in the range where the object material 80 is ground as the origin. For example, in Figure 7 the graph, the graph of the speed function V(P) is symmetric about the position P i included in the range where the object material 80 is ground. Therefore, Figure 7 the speed function V(P) of the graph in i is an even function with P Figure 8 as the origin. In addition, in i the graph, the graph of the pressure application function F(P) is symmetric about the position P Figure 8 included in the range where the object material 80 is ground. Therefore, i the pressure application function F(P) of the graph in

[0108] <Flowchart>

[0109] The grinding system 1 can also execute including Figure 9A manufacturing method for a product of the process of the flowchart exemplified. The manufacturing method of the product may include a trajectory generation method for the control device 12 of the grinding system 1 to generate a grinding trajectory. The manufacturing method of the product or the trajectory generation method may also be implemented as a manufacturing program or a trajectory generation program for causing a processor included in the control device 12 of the grinding system 1, etc. to execute. The manufacturing program or the trajectory generation program may be stored in a non-transitory computer-readable medium.

[0110] The shape measurement device 32 measures the shape of the object material 80 to be ground (step S1). The removal object recognition device 30 identifies the removal object 82 included in the object material 80 based on the shape data of the object material 80 (step S2).

[0111] The control device 12 generates a grinding trajectory for the grinding performed by the grinding device 10 based on the measurement data of the shape of the object material 80 and the recognition result of the removal object 82 (step S3). The control device 12 drives the grinding device 10 based on the generated trajectory (step S4). The control device 12 obtains the measurement result of the grinding pressure from the pressure measurement device 14, and controls the grinding device 10 so that the measured value of the grinding pressure approaches the grinding pressure determined by the trajectory (step S5). The control device 12 determines whether the grinding has been completed (step S6). For example, the control device 12 may determine that the grinding has been completed when moving the grinding device 10 to the separation completion point P e0 . In the case where the grinding has not been completed (step S6: No), the control device 12 returns to the process of step S4 to continue driving the grinding device 10 until the grinding is completed. In the case where the grinding has been completed (step S6: Yes), the control device 12 ends Figure 9 the execution of the process of the flowchart. The grinding system 1 may further execute, as a manufacturing method of the product, a step of checking whether the removal object 82 has been removed after the grinding is completed. The trajectory generation method in the manufacturing method of the product may include Figure 9 the processes of steps S1 to S3.

[0112] Figure 9 The processes of steps S1, S2, and S3 in the process of the flowchart are processes for generating a trajectory. The grinding system 1 may also execute the processes including steps S1, S2, and S3 as a trajectory generation method.

[0113] As described above, according to the grinding system 1 and the grinding method of the present disclosure, the grinding device 10 is operated by using a locus in which the grinding speed and the grinding pressure are set, so that the step generated at the boundary between the ground portion and the unground portion is reduced. In addition, the control device 12 can generate a locus in such a manner that the posture, the grinding speed, or the grinding pressure of the grinding wheel 22 continuously changes during the movement of the grinding wheel 22 along the path 41. By operating the grinding device 10 by using the locus generated in this way, it is possible to minimize the step generated at the boundary between the ground portion and the unground portion while removing the object to be removed 82.

[0114] (Embodiment)

[0115] In the embodiment, the control device 12 generates a locus by setting the grinding speed by Equation (1) and setting the grinding pressure by Equation (2). The control device 12 sets the coefficients of Equation (1) and Equation (2) to the following values. These coefficients can be appropriately changed according to the size of the object to be removed 82 or the material of the object material 80 to be ground. In the embodiment, the coefficients are set such that the grinding speed V is the slowest and the grinding pressure F is the largest near the center of the path 41 for grinding the object to be removed 82.

[0116] a v1 =-2000, a v2 =(P e -P s ) / 2

[0117] b v1 =0, b v2 =-(P e -P s ) / 2

[0118] c v1 =1000, c v2 =-(P e -P s ) / 2

[0119] d v1 =0, d v2 =-(P e -P s ) / 2

[0120] e v =V min =10

[0121] a f1 =1800, a f2 =-(P e -P s ) / 2

[0122] b f1 =0, bf2 = (P e - P s ) / 2

[0123] c f1 = -900, c f2 = (P e - P s ) / 2

[0124] d f1 = 0, d f2 = (P e - P s ) / 2

[0125] e f = F max = 150

[0126] In addition, Equation (1) and Equation (2) are set to satisfy the following boundary conditions at the grinding start point P s and the grinding end point P e .

[0127]

[0128]

[0129] The result of measuring the surface shape of the object material 80 after grinding under the above conditions as the grinding depth is shown by the solid line graph in Figure 10 . Figure 10 The horizontal axis of the graph in represents the position in the feed direction of the grinding tool. The vertical axis represents the grinding depth at each position. In the present embodiment, the change in the grinding depth with respect to the position in the feed direction changes smoothly and gently. By the smooth and gentle change in the grinding depth, the steps are reduced. In addition, the grinding depth exceeds the target value. As a result, re-grinding is not required.

[0130] On the other hand, as a method of a comparative example, a method of grinding without changing the grinding speed and the grinding pressure is considered. The result of measuring the surface shape of the object material after grinding by the method of the comparative example as the grinding depth is shown by the dotted line graph in Figure 10 . As a result of grinding by the method of the comparative example, with respect to the change in the position in the feed direction, particularly in the positions close to the grinding start point and the grinding end point, portions where the grinding depth changes sharply can be seen. Such sharply changing portions are judged as steps by sensory inspection using the tactile sense of an inspector or the like. As a result, re-grinding of the portions to be judged as steps is required.

[0131] As described above, in the grinding method according to the present embodiment, the quality of the grinding portion is improved compared to the method of the comparative example. In addition, the ratio required for re-grinding the grinding portion is reduced. Specifically, under the conditions of the above-described embodiment, the ratio that requires re-grinding is reduced by approximately 90%. As a result, approximately 40% of the entire grinding operation performed by the grinding device 10 is reduced.

[0132] Although the embodiments of the present disclosure have been described based on the respective drawings and examples, it should be noted that those skilled in the art can make various deformations or changes based on the present disclosure. Therefore, it should be noted that these deformations or changes are included in the scope of the present disclosure. For example, the functions included in each structural part or each step, etc. can be reconfigured in a logically non-contradictory manner, and multiple structural parts or steps, etc. can be combined into one or divided. The embodiments of the present disclosure can also be implemented as a program executed by a processor provided in a device or a storage medium recording the program. It should be understood that they are also included in the scope of the present disclosure.

[0133] Explanation of reference numerals

[0134] 1... Grinding system; 10... Grinding device; 12... Control device; 14... Pressing force measurement device; 20... Grinder; 22... Grinding wheel (22a: Rotating shaft, 24: Machining reference point); 30... Removal object recognition device; 32... Shape measurement device; 41, 42, 43... Paths; 80... Object material (82: Removal object, 84: Grinding surface, 85, 86: Tangents).

Claims

1. A grinding system, characterized in that, Comprising: A grinding device having a grinding tool for grinding a material to be ground; A pressure application measuring device for measuring the grinding pressure applied from the grinding tool to the material to be ground; And A control device that generates a trajectory of the grinding tool for grinding the object to be removed based on the three-dimensional shape of the surface of the object material and the position and shape of the object to be removed from the object material, and controls the grinding device so that the grinding tool moves based on the trajectory; The control device generates the trajectory such that at least one of the moving speed of the grinding tool relative to the object material or the grinding pressure changes according to the position of the grinding tool.

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

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

4. The grinding system according to any one of claims 1 to 3, wherein The control device generates the trajectory such that the absolute value of the function obtained by differentiating the first order of the speed function representing the moving speed of the grinding tool with the position of the grinding tool as a parameter is less than the speed first order differential threshold, and the absolute value of the function obtained by differentiating the first order of the pressure application function representing the grinding pressure with the position of the grinding tool as a parameter is less than the pressure application first order differential threshold.

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

6. The grinding system according to claim 5, wherein At least a part of the speed function and the pressure application function is represented by an even function with the position included in the range for grinding the object material as the origin.

7. The grinding system according to claim 6, wherein At least a part of the speed function and the pressure application function is represented by any one of a quartic equation, a sine function, or a Gaussian distribution of the position of the grinding tool.

8. A trajectory generation method for generating a trajectory of a grinding tool for controlling a material to be ground, The trajectory generation method is characterized by including: A step of measuring the three-dimensional shape of the surface of the object material; A step of identifying the position and shape of the object to be removed from the object material; And A step of generating the trajectory in such a manner that at least one of the speed of the grinding tool relative to the object material or the grinding pressure applied by the grinding tool to the object material varies according to the position of the grinding tool, based on the three-dimensional shape and posture of the object material and the position and shape of the object to be removed.

9. A manufacturing method of a product, characterized in that, Comprising the following steps: Controlling a grinding tool based on the trajectory generated by performing the trajectory generation method according to claim 8, and grinding an object to be removed from the object material.

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