JPH0716852B2 - Numerical control machine tool - Google Patents

Description

The present invention relates to a numerically controlled machine tool in which a machining operation is controlled based on a machining program input from the outside.

[Conventional technology]

Generally, in a conventional numerically controlled machine tool, a machining program input from the outside is read for each block (command information unit), and based on this, a machining device such as a spindle head to which a tool is attached is driven. Control is performed so that the processing device relatively moves along the outer shape of the workpiece.

By the way, a program for controlling such a machine tool includes a command including only a translational movement of the above-mentioned processing apparatus like a three-axis control program, and a translational movement like a four-axis or five-axis control program. In addition to this, there is a command including a turning movement command. In the control by the program of translational movement only, the tool attached to this device always faces a certain direction during the driving of the machining device. The inclination of the tool with respect to will also change.

[Problems to be Solved by the Invention]

For example, when the control based on the three-axis control program is performed, the tool always takes a posture that faces a certain direction as the basic posture as described above. Therefore, when the workpiece 101 as shown in FIG. 8 is machined, the workpiece 101 and the machining device 102 interfere with each other in the illustrated corner portion (two-dot chain line in the same figure).
There was a problem that processing became difficult.

On the other hand, when the 4-axis or 5-axis control program is used, the processing device 102 that does not interfere with the workpiece 101
Set the orientation of the processing device 10 so that it matches this orientation.
The above problem can be solved by controlling the turning of 2. However, when trying to perform control including turning of the processing device 102 in this way, complication of the program cannot be avoided, an expensive program creation device is required, and the number of man-hours for creating the program increases, resulting in cost reduction. There is a problem leading to a rise. Particularly in the case of 5-axis control, the program becomes more complicated and it is difficult to put it into practical use.

In view of such circumstances, the present invention provides a numerically controlled machine tool that can appropriately control the drive of a processing device while avoiding interference between the processing device and a workpiece based on a simple program. With the goal.

[Means for Solving the Problems]

The present invention has a tool for processing a work piece, and a processing device configured such that an angle between the tool and the surface of the work piece is variable, and the processing device with respect to the work piece. And a moving means for moving the angle, and a reading means for reading a machining program input via an external input device, and a movement command for the machining apparatus in the read machining program. A numerically controlled machine tool, comprising: a control means for controlling the drive means so that the processing device moves based on a block so as to move with respect to a workpiece, the processing device having the basic position. Interference determining means for determining whether or not the workpiece interferes with the work piece, and the orientation of the processing apparatus so that interference can be avoided in the area determined to interfere by the interference determining means. And an arithmetic means for, is obtained by configuring the control means to perform the drive control of the processing unit in the interference determination area based on the calculation result.

[Work]

According to the above configuration, based on the read machining program, it is determined whether or not the machining device in the basic posture interferes with the workpiece, and in the interfering area, the interference of the machining device can be avoided. The orientation is calculated, and appropriate drive control of the processing device is performed based on the calculation result.

(Embodiment) An embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a diagram showing an outline of the numerically controlled machine tool in this embodiment. In the figure, 1 is a spindle head (machining device) for machining a workpiece 6, and the spindle head 1 has a chuck 1a to which a tool 2 such as an end mill is removably attached, and the tool 2 It has a built-in motor for rotating the.

The spindle head 1 and the workpiece 6 are relatively moved in three directions by driving the machining feed devices (driving means) 3, 4, 5. That is, each processing feeding device 3
5 to 5 are provided with a servo motor 19 (see FIG. 1 described later), and the machining feed device 3 moves the workpiece 6 in the X-axis direction (direction perpendicular to the plane of the drawing) with respect to the spindle head 1 to feed the machining feed device. Four,
5 is configured to move the spindle head 1 with respect to the workpiece 6 in the Y-axis direction (left-right direction in the drawing) and the Z-axis direction (up-down direction in the drawing). As a result, the spindle head 1 translates with respect to the workpiece 6.

Further, the main spindle head 1 is, as shown in FIG.
The servo motor 19 is rotatable about an axis (axis parallel to the X axis) and a C axis (axis parallel to the Z axis), and is built in the machine tool body side as drive means (FIG. 1 described later). Thus, it is adapted to be driven to rotate around these axes. As a result, the spindle head 1 pivotally moves with respect to the workpiece 6, and the orientation of the tool with respect to the workpiece 6 changes.

FIG. 1 is a block diagram showing the functional configuration of this numerically controlled machine tool. The external input device 11 in the figure is composed of, for example, a perforated tape, a floppy disk, or the like, and records a processing program containing information necessary for processing. The reading unit 12 reads the content of the program recorded in the external input device 11, and analyzes and checks the command command.

Based on the movement command blocks in the read program, the basic calculation unit 13a calculates a vector (that is, a normal vector) in a direction perpendicular to the workpiece 6 at the start point and the end point of these movement command blocks. ,
The turning angle of the spindle head 1 is calculated so that the orientation of the tool 2 matches this vector. By this calculation, the attitude that the processing apparatus takes during normal processing, that is, the basic attitude is determined.

The interference determination unit 14 determines whether or not the spindle head 1 having the basic attitude thus calculated interferes with the workpiece 6 by the movement according to the movement command block. The interference avoidance calculation unit 13b uses a vector corresponding to the orientation of the spindle head 1 (that is, an interference avoidance vector) that enables interference avoidance instead of the normal vector in the area determined to interfere by the interference determiner 14. ) Is calculated and the corresponding swing angle of the spindle head 1 is calculated.

The control unit 15 includes a command unit 16, a positioning pulse distribution circuit 17, and a servo amplifier 18, and controls the drive of each servo motor 19 based on the calculation result of the basic calculation unit 13a or the interference avoidance calculation unit 13b. The position and speed information of the moving body (spindle head 1 or the workpiece 6) driven by each servo motor 19 is fed back to the control unit 15, whereby appropriate movement control based on the movement command block is performed.

Next, the operation of the numerically controlled machine tool will be described with reference to the flowchart of FIG. First, the reading unit 12 sequentially reads the machining program stored in the external input device 11 for each block and analyzes the command (step S ₁ ). The read block is the spindle head 1.
Surface normal vector (workpiece 6 on the specified plane if the moving is a command block (YES in step S _2), the prefetched two movement command block, at the start and end points for moving the Is calculated (step S ₃ ). This designated plane is
This is a surface on which the spindle head 1 moves in translation, and as a rule, the spindle head 1 is driven to rotate about an axis perpendicular to this plane. For example, when the designated plane is the XY plane, the spindle head 1 swivels around the C axis, and when the designated plane is the YZ plane, the spindle head 1 swivels around the A axis.

Next, it is determined whether or not interference will occur between the spindle head 1 and the workpiece 6 when the spindle head 1 moves in a posture that matches the normal vector, that is, in the basic posture ( Step S ₄ ). This determination can be made based on the relationship between the shape of the workpiece to be obtained by prefetching a plurality of blocks and the direction of the normal vector. For example, as shown in FIG. 5 (a), the normal vector at the point B as the end point of the movement command block (A → B) Alternatively, the normal vector at the point B as the start point of the movement command block (B → C) However, if the workpiece 6 faces inward from the outline of the workpiece 6, it can be determined that there is interference. Conversely, the binormal vector Is directed toward a predetermined range outside the outline of the workpiece 6, it can be determined that there is no interference.

When it is determined that there is interference as described above, a vector for avoiding interference is calculated as a vector set instead of the normal vector (step S ₅ ). In this embodiment, the workpiece 6 is used as the basic posture of the spindle head 1.
Since the posture is set to be substantially perpendicular to, there is a possibility that interference may occur at the valley-shaped corner portion B as shown in FIG. 5 (a). Therefore, in such a case, the center point P is set at an appropriate location outside the workpiece 6 as shown in FIG. 7B, and each point between the points A and C, which is the interference determination area, is set. At the center point P
Is calculated, and this is used as the interference avoidance vector. That is, if the orientation of the spindle head 1 matches this vector, the spindle head 1 and the workpiece 6 do not interfere with each other.

Based on such interference avoidance vector or the normal vector, the calculation of the turning angle of the spindle head 1 is performed (step S _6). That is, when it is determined that there is no interference, the turning angle of the spindle head 1 is assigned such that the tool 2 is perpendicular to the surface of the workpiece 6 at the start point and the end point of each block, and the interference occurs. If it is determined that there is, the turning angle of the spindle head 1 is assigned such that the orientation of the tool 2 matches the interference avoidance vector.

Along with this, the position correction amount of the tool 2 due to the turning of the spindle head 1 is calculated (step S ₇ ). For example,
When it is desired to move the cutting edge of the tool 2 from the point A to the point B as shown in FIG. 6, when the spindle head 1 is moved as it is, the cutting edge of the tool 2 deviates from the point B and is positioned at the point B ′ by the above-mentioned turning. Therefore, the correction amount for correcting such an error is calculated. For example, with point A as the origin,
Assuming that the coordinates of the point B are (x ₁ , y ₁ ), the cutting edge of the tool 2 is at the point A.
The amounts X ₁ and Y ₁ that the spindle head 1 has to move in the X-axis direction and the Y-axis direction to move from the point B to the point B are represented by the following formula, where the turning angle is θc and the turning radius is L. .

X ₁ = x ₁ −Δx Y ₁ = y ₁ −Δy However, Δx = L sin θc Δy = L (1-cos θc) Δx and Δy in these equations correspond to the above correction amount.

Next, the translational movement of the spindle head 1 obtained as described above and a command turning angle with are assigned to each block (step S _8), the editing program information into a form that includes the information takes place (step S _9). After that, each block is commanded into a form capable of executing an execution command (step S ₁₀ ), and the positioning pulse distribution circuit 17 distributes the pulse signal (step S ₁₁ ), and the servo amplifier 18 outputs this signal to the spindle head 1. is amplified to a value that corresponds to the feed rate (step S _12). This signal is input to each servo motor 19 and the servo motor 19 is driven (step S ₁₃ ), whereby the spindle head 1
Becomes possible to move to a predetermined position relative to the workpiece 6 (YES at step S _14).

By receiving such drive control, the spindle head 1
Moves in translation with respect to the workpiece 6 while maintaining a basic posture almost perpendicular to the workpiece 6 in the area where no interference occurs, and in the interference determination area, as shown in FIG. By performing the translational movement in the state of facing the center point P, the workpiece 6 is processed while avoiding interference.

Therefore, according to this machine tool, proper drive control of the spindle head 1 is performed while automatically avoiding the interference between the spindle head 1 and the workpiece 6 by using a relatively simple program for three-axis control. be able to.

Moreover, if a posture perpendicular to the workpiece 6 is set as the basic posture of the spindle head 1 as in this embodiment,
Deflection of the tool 2 caused by being pressed against the workpiece 6 is small, and there is an advantage that a machining error due to such deflection can be reduced.

The present invention does not necessarily require the basic calculation unit 13a for calculating the basic posture as shown in this embodiment, and the above effect can be obtained if at least the interference avoidance calculation unit 13b is provided. When the basic calculation unit 13a is not provided as described above, the orientations of the spindle head 1 and the tool 2 are not normally controlled, and they are always oriented in one direction. For example, as shown in FIG. 7 (a). Even in such a mountain-shaped corner portion B ', interference may occur between the spindle head 1 and the workpiece 6 (the vector at the point C'in the figure). reference). In this case, the center point P ′ is inside the workpiece 6.
Is set and the angle of the spindle head 1 is controlled so as to always face the center point P ′, it is possible to perform cornering while avoiding interference as in the above.

Further, in the embodiment, the case where the spindle head 1 controls a machine tool that can move about five axes by using a three-axis control program is shown, but in the present invention, the processing device translates at least in two directions on a designated plane. It is applicable to any machine tool that is movable and can rotate around an axis perpendicular to the plane.

〔The invention's effect〕

As described above, according to the present invention, based on the movement command block of the processing device in the read processing program, the interference determination means for determining whether or not the processing device in the basic posture interferes with the workpiece is And a calculation means for calculating the orientation of the processing apparatus that can avoid interference in the determined area, and based on the calculation result, the angle between the tool and the workpiece in the interference determination area is controlled. Therefore, based on a relatively simple and low-cost program relating only to the translational movement of the processing device, while appropriately avoiding the interference between the processing device and the workpiece, the proper drive control of the processing device is performed. There is an effect that can be done.

[Brief description of drawings]

FIG. 1 is a block diagram showing a functional configuration of a numerically controlled machine tool according to an embodiment of the present invention, FIG. 2 is a schematic front view of the machine tool, and FIG. 3 is a perspective view near a spindle head of the machine tool. FIG. 4 is a flow chart showing the operation of the machine tool, FIG. 5 (a) is an explanatory view showing normal vectors at the start point and end point of a movement command block given to the machine tool, and FIG. 4 (b) is the movement. FIG. 6 is an explanatory view showing the actual inclination of the tool in the command block, FIG. 6 is an explanatory view showing the position correction procedure of the calculation performed by the machine tool, and FIGS. 7 (a) and 7 (b) are views of the tool in another embodiment. FIG. 8 is an explanatory diagram for explaining the orientation control, and FIG. 8 is an explanatory diagram showing the relationship between the tool and the workpiece in the conventional numerically controlled machine tool. 1 ... Spindle head (machining device), 3,4,5 ... Machining feed device (driving means), 6 ... Workpiece, 11 ... External input device, 12 ... Read part, 13b ... Interference Avoidance calculation unit (calculation means), 14 ... interference determination unit, 15 ... control unit, 19 ... servo motor.

Claims (1)

[Claims] 1. A processing apparatus having a tool for processing a workpiece, wherein the angle between the tool and the surface of the workpiece is variable, and the processing apparatus is used as the workpiece. A reading means for reading a machining program input via an external input device, and a movement of the machining apparatus in the read machining program, the reading means being provided with a driving means for relatively moving the machining program and changing the angle. In a numerically controlled machine tool equipped with a control means for controlling the drive means so that the processing device moves with respect to the workpiece while maintaining the basic posture based on the command block, the machining in the basic posture is performed. The interference determination means for determining whether or not the apparatus interferes with the workpiece, and the orientation of the processing apparatus so that interference can be avoided in the area determined to interfere with the interference determination means. And an arithmetic means for calculation for numerical controlled machine tool being characterized in that constitute the control means to perform the drive control of the processing unit in the interference determination area based on the calculation result.