Numerical control device

Abstract

The present invention provides a numerical control device capable of easily and accurately performing a trial run without the tool interfering with the workpiece. The numerical control device according to one aspect of the present disclosure controls a machine tool that processes a workpiece with a tool according to a machining program, and the numerical control device includes: an offset setting unit that determines an offset direction and an offset amount based on the orientation of each tool; a trial run path calculation unit that calculates a trial run movement path of the tool obtained by offsetting the machining movement path of the tool specified by the machining program in the offset direction by the offset amount; and an operation mode selection unit that selects either a machining operation mode in which the tool moves along the machining movement path or a trial run mode in which the tool moves along the trial run movement path.

Description

Technical Field

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

[0002] A machining system including a machine tool for machining a workpiece and a numerical control device for controlling the machine tool according to a machining program is widely used. In such a machining system, before actually machining the workpiece, the machine tool is sometimes operated experimentally in such a way that the tool moves to a position where it does not act on the workpiece (does not contact the workpiece) to confirm whether the machining program is appropriate.

[0003] Generally, by temporarily changing the set value of the length of the tool (the distance between the chuck and the cutting edge), the tool can be moved in such a way that it passes through a position retracted from the position according to the machining program without interfering with the workpiece. However, depending on the type of the tool, the cutting direction of the tool is different from the direction connecting the chuck and the cutting edge, so that sometimes even if the set value of the length of the tool is changed, it is impossible to avoid the interference of the tool with the workpiece. In addition, after changing the set value of the length of the tool and performing a trial operation, it is necessary to restore the set value of the length of the tool to an appropriate value, but it may be impossible to perform appropriate machining due to forgetting this operation or setting the set value of the length of the tool to an incorrect value.

[0004] In order to easily perform a trial operation of the machine tool, a numerical control device is proposed, which includes a movement amount calculation unit that calculates, for each cutting operation of one cutting operation or a plurality of cutting operations according to a cutting instruction of a machining program, the difference between the movement start position and the movement end position, that is, the movement amount, and the numerical control device includes an offset amount determination unit that determines the maximum movement amount among the movement amounts calculated by the movement amount calculation unit as the offset amount (for example, refer to Patent Document 1).

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent No. 4867876 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] In the method described in Patent Document 1, the longest distance among the movement amounts of the Z axis is set as the offset amount of the tool (the retraction amount from the position according to the machining program). However, in this method, in a machine tool that performs complex operations such as a 5-axis machining center, it may not be possible to appropriately avoid interference of the tool with the workpiece. Therefore, a numerical control device that can easily and reliably perform a dry run to prevent the tool from interfering with the workpiece is desired.

[0010] Solutions for Solving the Problems

[0011] The numerical control device according to one aspect of the present disclosure controls a machine tool that machines a workpiece with a tool according to a machining program, and includes: an offset setting unit that determines an offset direction and an offset amount based on the orientation of each tool; a dry run path calculation unit that calculates a dry run path of the tool obtained by offsetting the machining movement path of the tool specified by the machining program in the offset direction by the offset amount; and an operation mode selection unit that selects either a machining operation mode in which the tool moves along the machining movement path or a dry run mode in which the tool moves along the dry run path.

[0012] Effects of the Invention

[0013] According to the numerical control device of the present disclosure, a dry run that prevents the tool from interfering with the workpiece can be easily and accurately performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic diagram showing the structure of a machining system including a numerical control device according to an embodiment of the present disclosure.

[0015] Figure 2 is a diagram showing Figure 1 the offset in the case where the tool in the machining system is a ball nose end mill.

[0016] Figure 3 is a diagram showing Figure 1 the offset in the case where the tool in the machining system is a side mill.

[0017] Explanation of Reference Signs

[0018] 1: Numerical control device; 21: Program storage unit; 22: Coordinate system storage unit; 23: Tool data storage unit; 24: Machining path calculation unit; 25: Offset setting unit; 26: Dry run path calculation unit; 27: Operation mode selection unit; 28: Operation control unit; 251: Offset direction determination unit; 252: Offset amount determination unit; 100: Machining system; T: Tool; W: Workpiece. Detailed implementation manners

[0019] Hereinafter, the implementation manners of the present disclosure will be described with reference to the drawings. Figure 1 FIG. is a schematic diagram showing the structure of a machining system 100 including a machine tool 1 and a numerical control device 2 according to an embodiment of the present disclosure.

[0020] The machine tool 1 is a device that performs cutting on a workpiece W by causing a tool T rotated by a spindle Am to act on the workpiece W. The machine tool 1 can be, for example, a device that performs cutting on a workpiece W held on a worktable B by a tool T held by a machining head H, and has a plurality of drive axes capable of relatively moving the tool T (machining head H) relative to the workpiece W (worktable B). There is no particular limitation on the specific axis structure of the machine tool 1, but as an example, the machine tool 1 can be a five-axis machining machine having linear axes Ax, Ay, Az orthogonal to each other, a rotary axis Ab parallel to the linear axis Ay, and a rotary axis Ac parallel to the linear axis Az as the plurality of drive axes.

[0021] The numerical control device 2 controls the spindle Am and the drive axes Ax, Ay, Az, Ab, Ac of the machine tool 1 according to a machining program. The numerical control device 2 can be realized, for example, by causing a computer device having a CPU, a memory, an input / output interface, etc. to execute an appropriate control program. The numerical control device 2 can also be configured to communicate with a management server that manages a plurality of machining systems 100.

[0022] The numerical control device 2 includes a program storage unit 21, a coordinate system storage unit 22, a tool data storage unit 23, a machining path calculation unit 24, an offset setting unit 25, a trial run path calculation unit 26, an operation mode selection unit 27, and an operation control unit 28. In addition, these components may be functionally distinct and cannot be clearly distinguished in the physical structure and program structure.

[0023] The program storage unit 21 stores machining programs. The program storage unit 21 can be configured to store a plurality of machining programs and select a machining program indicated by a user or a management server from the stored plurality of machining programs. The structure of the program storage unit 21 can be set to the same structure as the program storage unit in a conventional numerical control device.

[0024] The coordinate system storage unit 22 stores the coordinate system of the workpiece W. Thereby, the numerical control device 2 can mutually convert the coordinate system of the machine tool 1 and the coordinate system of the workpiece W. The structure of the coordinate system storage unit 22 can be set to the same structure as the coordinate system storage unit in a conventional numerical control device.

[0025] The tool data storage unit 23 stores, for example, information on the tool T required for machining the workpiece W, such as the type of the tool T, the cutting edge length, and the range of appropriate cutting speeds. The tool data storage unit 23 stores the values of the offset direction and the offset amount directly used in the offset setting unit 25 described later. Specifically, the tool data storage unit 23 can be configured to store a table associating the numbers or IDs of a plurality of tools T with a plurality of pieces of information required for machining.

[0026] The machining path calculation unit 24 calculates the movement path of the tool T according to the machining program stored in the program storage unit 21. Specifically, the machining path calculation unit 24 analyzes the machining program to calculate the position and posture of the tool T at each time specified by the machining program, and further calculates the positions of the drive shafts Ax, Ay, Az, Ab, and Ac at each time for achieving the position and posture.

[0027] The offset setting unit 25 includes: an offset direction determination unit 251 that determines, for each tool T, an offset direction Dd, which is the direction in which the tool T retreats from the machining movement path with the orientation of the tool T (in the present embodiment, the orientation of the rotation axis coinciding with the main shaft Am) as a reference during the trial run; and an offset amount determination unit 252 that determines an offset amount Da, which is the distance by which the tool T retreats from the machining movement path.

[0028] The offset direction determination unit 251 sets the offset direction stored in the tool data storage unit 23 as the offset direction of the currently used tool T. In addition, in the case where the offset direction is not stored in the tool data storage unit 23, it can also be configured to set the offset direction as the rotation axis direction of the tool T (the direction of the main shaft Am). For most tools T, offsetting along the rotation axis direction is appropriate. Therefore, by setting it such that the input of the offset direction can be omitted when the offset direction is the rotation axis direction, user convenience can be improved.

[0029] The offset direction determination unit 251 may also determine the offset direction Dd of the tool T according to the type of the tool T. That is, the offset direction determination unit 251 may be configured to determine the offset direction Dd of the tool T according to the type of the tool T stored in the tool data storage unit 23. Therefore, the offset direction determination unit 251 may also store a table representing the relationship between the type of the tool T and the offset direction Dd.

[0030] As a specific example, in Figure 2When the tool T is a ball-nose end mill as shown, the offset direction determination unit 251 preferably sets the offset direction Dd to the direction of the rotation axis of the tool T (that is, the spindle Am). In particular, when the machine tool 1 is a 5-axis machining center and the tool T is a ball-nose end mill, as shown on the left side of the figure, even if the tool T is offset in the z direction along the vertical linear axis Az, the tool T may interfere with the workpiece W. Therefore, as shown on the right side of the figure, the tool T is offset in the direction of the rotation axis (Am) of the tool T, thereby preventing the tool T from interfering with the workpiece W.

[0031] In addition, when the tool T is a face mill as shown in Figure 3 the offset direction determination unit 251 preferably sets the offset direction Dd to a direction perpendicular to the rotation axis (Am) of the tool T. When the tool T is a face mill, as shown on the left side of the figure, even if the tool T is offset in the direction of the rotation axis (Am) of the tool T, the tool T may interfere with the workpiece. Therefore, as shown on the right side of the figure, the tool T is offset in a direction perpendicular to the rotation axis (Am) of the tool T, thereby preventing the tool T from interfering with the workpiece W.

[0032] The offset amount determination unit 252 can analyze the machining program to calculate the cutting-in amount and set the offset amount Da of the tool T to a value equal to or greater than the cutting-in amount. However, the offset amount Da of the tool T can also be determined based on the cutting edge length of the tool T. Specifically, the offset amount determination unit 252 can set the offset amount Da to the cutting edge length of the tool T, or to a value obtained by multiplying the cutting edge length by a specified coefficient (safety factor). In machining where the number of cutting-ins is one, such as finish machining, the cutting-in amount of the tool T cannot reach more than the cutting edge length. Therefore, in the machining program, the cutting-in amount of the tool T is set to be less than or equal to the cutting edge length of the tool T. Therefore, if the offset amount is set to be greater than the cutting edge length of the tool T, the tool T can be prevented from interfering with the workpiece W.

[0033] The trial operation path calculation unit 26 calculates the trial operation moving path of the tool T that is offset by the offset amount Da determined by the offset setting unit 25 in the offset direction Dd from the machining moving path calculated by the machining path calculation unit 24. The trial operation path calculation unit 26 determines the offset direction Dd at each moment of the machining moving path based on the posture of the tool T specified by the machining path calculation unit 24 at each moment. Thus, the optimal offset direction Dd is selected according to the posture of the tool T, and therefore, interference of the tool T with the workpiece W during the trial operation can be accurately prevented.

[0034] The operation mode selection unit 27 selects either a machining operation mode or a trial operation mode. The machining operation mode is a mode in which the tool T moves along the machining movement path calculated by the machining path calculation unit 24 to machine the workpiece W. The trial operation mode is a mode in which the tool T moves along the trial operation movement path calculated by the trial operation path calculation unit 26 without contacting the workpiece W. Thus, it is possible to easily switch between the trial operation in which the tool T is offset and moved without contacting the workpiece W and the machining operation in which the workpiece W is cut by the tool T without performing operations such as changing set values.

[0035] The operation control unit 28 generates an instruction signal input to the machine tool 1 so that the tool T moves along the machining movement path calculated by the machining path calculation unit 24 to machine the workpiece W, or performs a trial operation in which the tool T moves along the trial operation movement path calculated by the trial operation path calculation unit 26 without contacting the workpiece W. The structure of the operation control unit 28 can be set to the same structure as the operation control unit in a conventional numerical control device.

[0036] The offset setting unit 25 determines the offset direction Dd based on the orientation of each tool T. Therefore, the numerical control device 2 can appropriately prevent interference between the tool T and the workpiece W during the trial operation. In addition, the offset setting unit 25 determines the offset amount Da according to the tool T. Therefore, the offset amount Da of the tool T can be set to the minimum required size, and thus it is easier to confirm whether the machining program is appropriate.

[0037] The embodiments of the numerical control device according to the present disclosure have been described above. However, the numerical control device according to the present disclosure is not limited to the above embodiments. In addition, the effects described in the above embodiments are merely the best effects produced by the numerical control device according to the present disclosure, and the effects of the numerical control device according to the present disclosure are not limited to the effects described in the above embodiments.

[0038] The numerical control device according to the present disclosure may also be configured such that the machining path calculation unit and the trial operation path calculation unit are connected in series, and the operation mode selection unit enables or disables the function of the trial operation path calculation unit. Thus, it is possible to select whether the trial operation movement path obtained by offsetting the machining movement path calculated by the machining path calculation unit is output by the trial operation path calculation unit or the machining movement path calculated by the machining path calculation unit is directly output by the trial operation path calculation unit.

[0039] The numerical control device according to the present disclosure can also be used, for example, to control a machine tool that performs other machining operations such as turning, other than milling.

Claims

1. A numerical control device controls a machine tool for machining a workpiece with a tool according to a machining program, and the numerical control device includes: An offset setting unit that determines a retraction direction and a retraction distance of the tool with respect to the axial direction of the tool for each tool; A trial operation path calculation unit that calculates a trial operation movement path of the tool obtained by retracting the machining movement path of the tool specified by the machining program by the retraction distance in the retraction direction; And An operation mode selection unit that selects either a machining operation mode in which the tool moves along the machining movement path or a trial operation mode in which the tool moves along the trial operation movement path.

2. The numerical control device according to claim 1, wherein The offset setting unit determines the retraction distance based on the cutting edge length of the tool.

3. The numerical control device according to claim 1 or 2, wherein The offset setting unit determines the retraction direction based on the type of the tool.

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