Display device

Abstract

The present invention relates to a display device. The display device (1) includes: a motor position information acquisition unit (11) that acquires motor position information of at least one of a commanded position and an actual position of a motor (4); a mechanical information acquisition unit (12) that acquires mechanical information including a drive shaft structure, a tool shape, and an unprocessed workpiece shape; a machined surface shape simulation unit (13) that performs simulation of machining a workpiece based on a machining program, and calculates the shape of the machined surface of the machined workpiece based on the motor position information and the mechanical information; a machined surface shape measurement unit (14) that measures the shape of the machined surface of the machined workpiece actually machined based on the machining program; and a machined surface shape display unit (15) that simultaneously displays the machined surface shape calculated by the machined surface shape simulation unit (13) and the machined surface shape measured by the machined surface shape measurement unit (14).

Description

Technical Field

[0001] The present invention relates to a display device. Background Art

[0002] It is known that the accuracy of position control of a motor that drives each drive shaft of a machine tool has a great influence on the machining result. Therefore, various techniques for discriminating the main causes of machining surface defects or shape errors of a workpiece obtained by machining using a machine tool, for example, are known (for example, refer to Patent Documents 1 to 3).

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent No. 6366875

[0006] Patent Document 2: Japanese Patent No. 5197640

[0007] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2017-30066 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] However, there is currently no technique for directly comparing the machining surface shape calculated based on the motor position information with the machining surface shape obtained by actually measuring the machining surface of a machined workpiece, and it is currently in a situation where it takes a long time to determine the main causes of machining surface defects or shape errors.

[0010] Therefore, there is a need to provide a technique that can visually and directly compare the machining surface shape calculated based on the motor position information with the machining surface shape obtained by actually measuring the machining surface of a machined workpiece.

[0011] Solutions for Solving the Problems

[0012] One aspect of the present disclosure is a display device for displaying the shape of a machined surface of a workpiece. The display device includes: a motor position information acquisition unit that acquires motor position information of at least one of a commanded position and an actual position of a motor that drives a drive shaft of a machine tool; a machine information acquisition unit that acquires machine information including the drive shaft structure of the machine tool, the tool shape, and the shape of the unprocessed workpiece; a machined surface shape simulation unit that performs a simulation of machining the workpiece based on a machining program, and calculates the shape of the machined surface of the machined workpiece based on the motor position information acquired by the motor position information acquisition unit and the machine information acquired by the machine information acquisition unit; a machined surface shape measurement unit that measures the shape of the machined surface of the machined workpiece actually machined based on the machining program; and a machined surface shape display unit that simultaneously displays the machined surface shape calculated by the machined surface shape simulation unit and the machined surface shape measured by the machined surface shape measurement unit.

[0013] Effects of the Invention

[0014] According to the present disclosure, it is possible to visually and directly compare the machined surface shape calculated based on the motor position information with the machined surface shape obtained by actually measuring the machined surface of the machined workpiece. Therefore, it is possible to determine the main cause of machined surface defects or shape errors in a short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a functional block diagram showing the structure of a machining system including the display device according to the present embodiment.

[0016] Figure 2 is a diagram showing the display screen of the display device according to the present embodiment.

[0017] Figure 3 is a diagram for explaining a method of calculating a reference plane for the machined surface shape.

[0018] Figure 4 is a diagram for explaining the alignment of the position of the coordinates of the machined surface shape on the reference plane.

[0019] Explanation of Reference Signs

[0020] 1: Display device; 2: Numerical control device; 3: Servo control device; 4: Motor; 5: Machine tool; 11: Motor position information acquisition unit; 12: Machine information acquisition unit; 13: Machined surface shape simulation unit; 14: Machined surface shape measurement unit; 15: Machined surface shape display unit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] Next, an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0022] Figure 1 FIG. is a functional block diagram showing the structure of a processing system 100 including a display device 1 according to the present embodiment. As Figure 1 shown, the processing system 100 includes a display device 1, a numerical control device 2, a servo control device 3, a motor 4, and a machine tool 5.

[0023] The numerical control device 2 generates a position command for the motor 4 based on a machining program created by CAM (Computer Aided Manufacturing). The position specified by this position command is the command position of the motor 4. In addition, the numerical control device 2 stores mechanical information including the drive shaft structure of the machine tool 5, the tool shape, and the shape of the unprocessed workpiece, which will be described later, in a rewritable memory such as an EEPROM.

[0024] The servo control device 3 generates a drive current for the motor 4 based on the position command from the numerical control device 2 and the position feedback detected by an encoder provided in the motor 4.

[0025] The motor 4 is provided on the machine tool 5. The motor 4 includes a motor for driving a movable part of the machine tool 5, for example, a motor for driving a feed shaft of a tool or a feed shaft of a workpiece. An encoder (not shown) for detecting the rotational position (rotation angle) of the motor 4 is provided in the motor 4. The rotational position detected by the encoder is the actual position of the motor 4 and is used as position feedback. Here, since the rotational position of the motor 4 and the position of the movable part of the machine tool 5 are in a corresponding relationship, the rotational position detected by the encoder, that is, the position feedback, represents the position of the tool or the workpiece.

[0026] The machine tool 5 is, for example, a machine that performs cutting on the surface of a workpiece (object to be machined) using a tool such as a ball nose end mill. Each drive shaft of the machine tool 5 is driven by the motor 4.

[0027] Next, the display device 1 according to the present embodiment will be described in detail.

[0028] The display device 1 according to the present embodiment is constituted by an arithmetic processing device such as a computer including a CPU, a ROM, a RAM, etc. In Figure 1 an example in which the display device 1 is constituted by a computer different from the numerical control device 2 is shown, but the display device 1 may also be integrated with the numerical control device 2.

[0029] As Figure 1As shown, the display device 1 according to this embodiment includes a motor position information acquisition unit 11, a mechanical information acquisition unit 12, a machined surface shape simulation unit 13, a machined surface shape measurement unit 14, and a machined surface shape display unit 15.

[0030] The motor position information acquisition unit 11 acquires motor position information of at least one of the command position and the actual position of the motor 4 that drives each drive shaft of the machine tool 5. Specifically, the command position of the motor 4 is acquired from the numerical control device 2. In addition, the actual position of the motor 4 is acquired from the servo control device 3.

[0031] The mechanical information acquisition unit 12 acquires mechanical information including the drive shaft structure of the machine tool 5, the tool shape, and the shape of the workpiece before machining. Specifically, this mechanical information is acquired from the numerical control device 2. Alternatively, these mechanical information can also be acquired by directly inputting and setting by the user to the display device 1.

[0032] The machined surface shape simulation unit 13 performs a simulation of machining the workpiece based on the above-mentioned machining program created by CAM. In addition, the machined surface shape simulation unit 13 calculates the shape of the machined surface of the machined workpiece based on the motor position information acquired by the motor position information acquisition unit 11 and the mechanical information acquired by the mechanical information acquisition unit 12.

[0033] Specifically, the machined surface shape simulation unit 13 calculates the tool path based on the machining program and the motor position information of each drive shaft of the machine tool 5, and simulates the three-dimensional machining shape based on the tool shape and the shape of the workpiece before machining. The machined surface shape of the machined workpiece is acquired based on the result of this simulation.

[0034] The machined surface shape measurement unit 14 measures the machined surface shape of the machined workpiece that has actually been machined based on the above-mentioned machining program created by CAM and acquires this machined surface shape. As the measuring device, any device that can measure the machined surface shape can be used. For example, the machined surface shape of the machined workpiece can be acquired based on the measurement result obtained by using a conventionally known surface roughness meter or the like.

[0035] The machined surface shape display unit 15 simultaneously displays the machined surface shape calculated by the machined surface shape simulation unit 13 and the machined surface shape measured by the machined surface shape measurement unit 14. Here, Figure 2 is a diagram showing the display screen of the display device 1 according to this embodiment. As Figure 2As shown, the display device 1 involved in this embodiment can simultaneously display the processing surface shape obtained by simulation based on the command position, the processing surface shape obtained by simulation based on the actual position, and the processing surface shape based on the actual measurement result obtained by the processing surface shape measuring unit 14 in one display screen.

[0036] As an example, Figure 2 Each processed surface shape shown is an image of a certain area having a size of 3 mm in length x 6 mm in width viewed from obliquely above. The size of the surface concavity and convexity of all processed surface shapes relative to the reference surface is displayed in different colors between -3 μm and 3 μm.

[0037] Preferably, the processing surface shape display unit 15 displays each processing surface shape in a manner that their positions, angles, and magnifications are the same as each other. That is, the directions of the X-axis and Y-axis on each reference plane and the origin position of each processing surface shape are aligned. Thus, the comparison between each processing surface shape becomes easy.

[0038] In addition, it is more preferred that when any one of the position, angle and magnification of one of the three processing surface shapes is changed, the processing surface shape display unit 15 also changes the position, angle and magnification of the remaining processing surface shapes in linkage. For example, it is configured that when the user changes any one of the position, angle and magnification of one processing surface shape by mouse operation or touch panel operation, the remaining processing surface shapes are also automatically changed and displayed, and all processing surface shapes have the same position, angle and magnification.

[0039] also, Figure 2 An example is shown in which two machined surface shapes, namely, a machined surface shape based on a command position and a machined surface shape based on an actual position, which are machined surface shapes calculated by the machined surface shape simulation unit 13, are displayed simultaneously with the machined surface shape measured by the machined surface shape measurement unit 14, but the present invention is not limited thereto. Alternatively, only one of the two machined surface shapes may be displayed simultaneously with the machined surface shape measured by the machined surface shape measurement unit 14.

[0040] Here, refer to Figure 3 and Figure 4 , a method of displaying the machined surface shape calculated by the machined surface shape simulation unit 13 and the machined surface shape measured by the machined surface shape measurement unit 14 in a manner of positionally aligning them will be described. Figure 3 This is a diagram for explaining a method of calculating a reference surface of a machined surface shape. Figure 4 It is a diagram for explaining the alignment of coordinates of a machined surface shape on a reference plane.

[0041] In order to display the machined surface shape calculated by the machined surface shape simulation unit 13 and the machined surface shape measured by the machined surface shape measurement unit 14 in an aligned position, it is necessary to calculate the reference plane for each machined surface shape. Therefore, a method for calculating the equation of the reference plane based on the point cloud on the machined surface to be processed will be described. First, when the point Pn(Xn, Yn, Zn) on the machined surface is defined and the reference plane d = aX + bY + cZ, the distance ln from the point Pn on the machined surface to the reference plane d is expressed by the following equation (1).

[0042]

Equation 1

[0043] ln = |axn + bYn + cZn - d| / sqrt(a 2 + b 2 + c 2 ) ··· Equation (1)

[0044] The plane with the minimum sum L of the squares of the distances from each machining point is set as the reference plane. That is, a, b, c, and d that minimize L expressed by the following equation (2) are obtained.

[0045]

Equation 2

[0046] L = ∑ln 2 ··· Equation (2)

[0047] Specifically, a matrix A is defined as shown in the following equation (3), and the reference plane is calculated by performing singular value decomposition (SVD: Singular Value Decomposition) on this matrix A.

[0048]

Equation 3

[0049]

[0050] The vector v corresponding to the minimum singular value σ is the normal vector of the reference plane to be obtained. Therefore, once v = (a, b, c) is determined, the reference plane d can be calculated by the following equation (4).

[0051]

Equation 4

[0052] d = l / n ∑(aXn + bYn + cZn) ··· Equation (4)

[0053] As described above, a method for calculating the reference plane based on the coordinate values of the point cloud has been described, but it is not limited to this. For example, an ideal machined surface can also be set from the outside and used as the reference plane.

[0054] Next, after calculating the reference plane as described above, the coordinate system (X-axis and Y-axis) is re-determined on the calculated reference plane. In addition, a function representing the unevenness information z at the point (x, y) obtained by orthogonally projecting the machining point onto the reference plane is defined as in the following equation (5).

[0055]

Equation 5

[0056] z = f(x, y) ··· Equation (5)

[0057] Then, for example, when actually measuring the unevenness information of the machined surface with a measuring device such as a surface roughness meter, the measurement is performed in such a way that the directions and origin positions of the X-axis and Y-axis on the reference plane based on the motor position information are made to coincide. Thereby, the position alignment of each machined surface shape can be performed.

[0058] According to the present embodiment, the following effects are achieved.

[0059] In the display device 1 according to the present embodiment, it is configured to include: a motor position information acquisition unit 11 that acquires at least one of the command position and the actual position of the motor 4 that drives the drive shaft of the machine tool 5 as motor position information; a mechanical information acquisition unit 12 that acquires mechanical information including the drive shaft structure of the machine tool 5, the tool shape, and the shape of the workpiece to be machined; a machined surface shape simulation unit 13 that performs simulation of machining the workpiece based on the machining program, and calculates the shape of the machined surface of the machined workpiece based on the motor position information acquired by the motor position information acquisition unit 11 and the mechanical information acquired by the mechanical information acquisition unit 12; a machined surface shape measurement unit 14 that measures the shape of the machined surface of the machined workpiece that has actually been machined based on the machining program; and a machined surface shape display unit 15 that simultaneously displays the machined surface shape calculated by the machined surface shape simulation unit 13 and the machined surface shape measured by the machined surface shape measurement unit 14.

[0060] Thus, the machining surface shape calculated based on the motor position information and the machining surface shape obtained by actually measuring the machining surface of the machined workpiece can be directly compared visually. Therefore, the main cause of the poor machining surface or shape error can be determined in a short time. For example, in the case of poor machining or shape error, if no large difference is confirmed in the shapes of the various machining surfaces, it can be estimated that there is a problem with the machining program, and if differences are confirmed in the shapes of the various machining surfaces, it can be estimated that there is a problem with the tool, etc. In addition, if a difference is confirmed in the machining surface shape based only on the command position, it can be estimated that there is a problem with the position control of the motor 4, and if a difference is confirmed in the machining surface shape measured only by the machining surface shape measuring unit 14, it can be estimated that there is a problem with the tool, etc. Therefore, the effect obtained by adjusting the motor control that can be adjusted in a short time can be easily confirmed without actual machining.

[0061] In addition, in the present embodiment, the machined surface shape display unit 15 is configured to display the machined surface shape calculated by the machined surface shape simulation unit 13 and the machined surface shape measured by the machined surface shape measurement unit 14 in such a manner that their positions, angles, and magnifications are the same. This makes it easier to compare the machined surface shapes, and it is possible to identify the main cause of a machined surface defect or shape error in a shorter time.

[0062] In addition, in the present embodiment, the machined surface shape display unit 15 is configured so that when any one of the position, angle, and magnification of the machined surface shape calculated by the machined surface shape simulation unit 13 and the machined surface shape measured by the machined surface shape measurement unit 14 is changed, the machined surface shape display unit 15 also changes the position, angle, and magnification of the other machined surface shape in conjunction with each other. Thus, the comparison between the two can be made easier, and the main cause of the machined surface defect or shape error can be identified in a shorter time.

[0063] In addition, the present invention is not limited to the above-mentioned embodiment, and modifications and improvements within the scope that can achieve the purpose of the present invention are also included in the present invention.

Claims

1. A display device for displaying the shape of a machined surface of a workpiece, the display device comprising: a motor position information acquisition unit that acquires motor position information of at least one of a command position and an actual position of a motor that drives a drive shaft of the machine tool; a mechanical information acquisition unit that acquires mechanical information including a drive shaft structure of the machine tool, a tool shape, and a shape of an unprocessed workpiece; a machined surface shape simulation unit that performs a simulation of machining the workpiece based on a machining program, and calculates a shape of a machined surface of the machined workpiece based on the motor position information acquired by the motor position information acquisition unit and the mechanical information acquired by the mechanical information acquisition unit; a machined surface shape measuring unit that measures the shape of a machined surface of a machined workpiece that has actually been machined based on the machining program; and a machined surface shape display unit that simultaneously displays the machined surface shape calculated by the machined surface shape simulation unit and the machined surface shape measured by the machined surface shape measurement unit, Among them, When any one of the position, angle and magnification of the machining surface shape calculated by the machining surface shape simulation unit and the machining surface shape measured by the machining surface shape measurement unit is changed, the machining surface shape display unit also changes the position, angle and magnification of the other machining surface shape in a linked manner.

2. The display device according to claim 1, characterized in that The machined surface shape display unit displays the machined surface shape calculated by the machined surface shape simulation unit and the machined surface shape measured by the machined surface shape measurement unit so that their positions, angles, and magnifications are the same.

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