JP4084252B2 - End mill processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an end mill processing apparatus that pockets a pocket portion on a workpiece by cutting with an end mill, or processes a chevron portion on a workpiece.
[0002]
[Prior art]
In the conventional end mill processing apparatus, for example, as shown in FIGS. 7A and 7B, when pocket processing is performed on the inner peripheral processing surface W1a of the pocket portion W1 forming a true circle formed on the workpiece W. The following processing methods were adopted. That is, while the end mill 31 is rotated at the retracting point pt1 at the center of the pocket portion W1, the position of the end mill 31 with respect to the processing surface W1a passes through the approach path PS1 approaching the processing surface W1a from the retracting point pt1, and the processing surface W1a. To the shape path PS2 along the line. Then, after making one round of the shape path PS2, the position of the end mill 31 with respect to the machining surface W1a is returned to the retraction point pt1 through the retreat path PS3 spaced from the machining surface W1a. In this case, the radii of the approach path PS1 and the retreat path PS3 are set so as to form a substantially circular arc having a half radius with respect to the circular arc of the shape path PS2.
[0003]
[Problems to be solved by the invention]
However, this conventional end mill processing apparatus has the following problems. That is, at the transition point pt2 from the small-diameter approach path PS1 to the large-diameter shape path PS2 and at the transition point pt3 from the large-diameter shape path PS2 to the small-diameter retraction path PS3, the large and small arcs contact each other. Theoretically, it is in a state where it can continue.
[0004]
However, at these transition points pt2 and pt3, the acceleration acting in the normal direction of the inner peripheral machining surface W1a changes abruptly, so that a control error occurs and a step on the shape path PS2 as shown in FIG. PS2a and PS2b are generated. In this case, as shown in the figure, the transition point pt2 from the approach path PS1 to the shape path PS2 and the transition point pt3 from the shape path PS2 to the retreat path PS3 are at the same position, but between the two steps PS2a and PS2b. There is a timing gap. For this reason, as shown in FIG. 9, an uncut protrusion W1b is generated on the inner peripheral surface W1a of the workpiece W.
[0005]
When the inner milling surface W1a of the workpiece W is machined, when the end mill 31 makes one round of the shape path PS2 and reaches the transition point pt2 from the previous approach path PS1 to the shape path PS2, the machining surface W1a. The cutting force at the machined portion of the steel is reduced and the cutting reaction force is reduced. For this reason, the escape of the end mill 31 (curvation in a direction away from the machining surface W1a) is recovered, and as shown in FIG. 9, an excessively cut recess W1c is generated on the inner circumferential machining surface W1a of the workpiece W. Therefore, the machining error on the machining surface W1a is doubled by the uncut shaving W1b and the overcutting recess W1c, leading to a reduction in machining accuracy.
[0006]
In order to cope with such a problem, for example, a processing method has been conventionally proposed in which a transition is made from the approach path PS1 to the shape path PS2, and after the shape path PS2 has made two rounds, the processing path returns to the retreat point pt1 through the retreat path PS3. ing. According to this processing method, in the shape pass PS2 of the second round, the uncut portion of the projection W1b can be cut off, but a new problem arises that the processing time becomes longer and the work efficiency decreases. It was.
[0007]
The present invention has been made paying attention to such problems existing in the prior art. The main object of the present invention is to provide an end mill machining apparatus that can suppress the occurrence of uncut protrusions on the machining surface and improve machining accuracy.
[0008]
A further object of the present invention is to provide an end mill processing apparatus that can suppress the occurrence of an excessively cut recess on the processed surface and can further improve the processing accuracy.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is directed to the position of the end mill relative to the circular machining surface of the workpiece, the approach path approaching the machining surface, the shape path along the machining surface, and the machining surface. In an end mill machining apparatus that sequentially shifts according to a retreat path that is separated from the workpiece and cuts the workpiece surface, control is performed so that the curvature of the movement path of the end mill continuously changes from the approach path to the shape path. In addition, the curvature of the trajectory of the end mill is continuously changed from the shape path to the retract path, and the transition point from the shape path to the retract path is closer to the transition point from the approach path to the shape path. It is characterized by providing a control means for controlling to become.
[0010]
Therefore, according to the first aspect of the present invention, when the transition from the approach path to the shape path is performed, the curvature of the movement path of the end mill continuously changes, so that the acceleration acting in the normal direction of the machining surface is increased. It changes continuously without changing rapidly. Therefore, it is possible to suppress the occurrence of a large control error due to an abrupt change in acceleration. Therefore, it is possible to suppress the occurrence of uncut protrusions on the processing surface, and the processing accuracy can be improved. In addition, since the shape pass is performed only once, unlike the case where the shape pass is performed twice, the processing time does not become long and a predetermined processing efficiency can be maintained.
[0012]
Also, according to the invention described in claim 1, in the transition from the shape path to the save path continuously changes without acceleration acting in the normal direction of the processing surface is rapidly changed. Therefore, it is possible to reliably suppress the occurrence of uncut protrusions on the processed surface, and the processing accuracy can be further improved.
[0014]
Furthermore , according to the first aspect of the present invention, in the vicinity of one round of the shape path, it is possible to suppress the occurrence of an excessively cut recess on the processed surface due to the reduction of the cutting reaction force, Processing accuracy can be further improved.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, in this end mill processing apparatus, a table 12 is disposed on an upper surface of one side of the base 11. A workpiece W is detachably mounted on the upper surface of the table 12, and a pocket portion W1 having, for example, a side circular shape is formed on a side surface of the workpiece W.
[0016]
A saddle 13 is supported on the other upper surface of the base 11 so as to be movable in the Z-axis direction via a pair of guide rails 14 and is moved in the same direction via a ball screw 16 by a Z-axis direction moving motor 15. It has become. A column 17 is supported on the saddle 13 so as to be movable in the X-axis direction via a pair of guide rails 18 and is moved in the same direction via a ball screw 20 by an X-axis direction moving motor 19. .
[0017]
A spindle head 21 is supported on the column 17 via a pair of guide rails 22 so as to be movable in the Y-axis direction, and is moved in the same direction by a Y-axis direction moving motor 23 via a ball screw (not shown). ing. A main shaft 24 is rotatably supported by the main shaft head 21, and an end mill 25 for cutting the workpiece W is detachably attached to the tip of the main shaft 24. A spindle rotating motor 26 is mounted on the spindle head 21, and the end mill 25 is rotated about its own axis via the spindle 24 by the motor 26.
[0018]
Next, the circuit configuration of the end mill processing apparatus will be described. As shown in FIG. 2, a memory 28 is connected to a control device 27 as a control means, and this memory 28 is a program for controlling the operation of the entire end mill processing device, various data used for executing the program, and the like. Is remembered.
[0019]
An input device 29 such as a keyboard is connected to the input side of the control device 27, and various data input signals, operation instruction signals, and the like are input from the input device 29 to the control device 27. Further, as shown in FIG. 1, whether or not the input device 29 performs pocket machining on the inner peripheral machining surface W1a of the pocket W1 of the workpiece W, as shown in FIG. It is selected whether or not to process the outer peripheral processed surface W2a of the portion W2 and a selection signal is input to the control device 27. The movement motors 15, 19, 23 and the spindle rotation motor 26 are connected to the output side of the control device 27, and the control device 27 supplies these motors 15, 19, 23, 26 to the pocket processing or the yama processing. A drive signal is output.
[0020]
That is, in the memory 28, as shown in FIGS. 1 and 3, the position data indicating the movement trajectory of the end mill 25 with respect to the machining surface W1a when pocketing the inner circumferential machining surface W1a of the pocket W1 of the workpiece W. Is remembered. In this case, the approach path PS1 approaching the processing surface W1a from the retreat point pt1 inside the processing surface W1a, the shape path PS2 along the processing surface W1a, and the retreating path PS3 separated from the processing surface W1a and returning to the retraction point pt1. Each position data is stored separately.
[0021]
Further, in the memory 28, as shown in FIG. 6A, position data indicating a movement locus of the end mill 25 with respect to the machining surface W2a when the outer circumferential machining surface W2a of the chevron W2 of the workpiece W is processed. Is also remembered. In this case, as shown in FIG. 6B, the approach path PS1 approaching the machining surface W1a from the retract point pt1 outside the machining surface W2a, the shape path PS2 along the machining surface W1a, and the machining surface W1a are separated from each other. The position data of the retreat path PS3 returning to the retreat point pt1 is stored separately.
[0022]
The control device 27 operates the motors 15, 19, 23, and 26 based on the position data stored in the memory 28 when selecting the pocket machining or the mountain machining using the input device 29. Thereby, while the end mill 25 is rotated, the position of the end mill 25 with respect to the machining surfaces W1a and W2a is shifted in the order of the approach path PS1, the shape path PS2, and the retreat path PS3, and pocket machining or yama is performed on the machining surfaces W1a and W2a. Processing is applied.
[0023]
Further, as shown in FIGS. 3 and 6B, the memory 28 shows the movement trajectory of the end mill 25 in the vicinity of the transition point pt2 from the approach path PS1 to the shape path PS2 at the time of pocket processing and YAMA processing. Position data that continuously changes the curvature is stored. Similarly, also in the vicinity of the transition point pt3 from the shape path PS2 to the retreat path PS3, position data that continuously changes the curvature indicating the movement locus of the end mill 25 is stored. The position data near these transition points pt2 and pt3 are created by the following method, for example.
[0024]
That is, when creating position data near the transition point pt2 from the approach path PS1 to the shape path PS2, a method as shown in FIG. 4 is employed. First, as shown in FIGS. 4 (a) to 4 (d), a curve formed by a continuous line segment a0a1, a1a2,..., An-1an so that the curvature continuously changes from a point a0 on the shape path PS2. Make a0-an. In this case, the radii of curvature R1, R2,..., Rn from the centers c1, c2,..., Cn to the points a1, a2,. Note that d indicates a curvature change rate (1 / m) / rad.
[0025]
Rn = 1 / {(1 / Rn-1) + d · Δθ} (1)
Here, the position of the center cn is determined so that the length of the line segment cnan-1 becomes the radius Rn on the line segment cn-1an-1. The position of the point an is determined so that the length of the line segment cnan is the radius Rn and the angle an-1 · cn · an is Δθ.
[0026]
Then, as shown in FIG. 4E, when the point an enters inside the region of the cutting white dr of the shape path PS2, the radius that touches the line an-1an at the point an and passes through the center c0. An arc Cf of R0 / 2 is created. In this case, since the point an is out of the region of the cutting white dr of the shape path PS2, it is not necessary to make the same curvature continuous.
[0027]
Thereafter, an approach path PS1 is created by passing a circular curve Cf from the center c0 and tracing back a series of curve shapes passing through the minute line segments anan-1, ..., a2a1, a1a0 to the point a0. Therefore, based on the position data created in this way, the curvature can be controlled to change continuously in the vicinity of the transition point pt2 from the approach path PS1 to the shape path PS2.
[0028]
Further, for the position data near the transition point pt3 from the shape path PS2 to the retreat path PS3, a method similar to the method of creating the position data near the transition point pt2 from the approach path PS1 to the shape path PS2 is reversed. Can be created. Based on this position data, the curvature can be controlled to change continuously in the vicinity of the transition point pt3 from the shape path PS2 to the retreat path PS3.
[0029]
Further, when creating position data near the transition point pt3 from the shape path PS2 to the retreat path PS3, as shown in FIG. 5, it is set so that the shape path PS2 is finished early and the process proceeds to the retreat path PS3. ing. In other words, the transition point pt3 from the shape path PS2 to the retreat path PS3 is set to be closer to the transition point pt2 from the approach path PS1 to the shape path PS2 by a predetermined angle δ. The angle δ may be arbitrarily selected and set according to the material of the workpiece W, the cutting speed, the tool diameter, the shape path curvature, and the like.
[0030]
Next, the operation of the end mill processing apparatus configured as described above will be described.
In this end mill processing apparatus, as shown in FIG. 1, when the inner peripheral processing surface W1a of the pocket portion W1 formed on the side surface of the work W is pocketed by cutting by the end mill 25, the input device 29 is used. To select the pocket machining mode. Thereafter, when the operation of the apparatus is started, the position of the end mill 25 with respect to the processing surface W1a is based on the position data stored in the memory 28 as shown in FIG. Thus, the process proceeds in order so as to pass through the approach path PS1, the shape path PS2, and the retreat path PS3. Then, while the end mill 25 makes one round along the shape path PS2, pocket machining is performed on the inner circumferential machining surface W1a of the workpiece W.
[0031]
In this case, the curvature of the movement locus of the end mill 25 is continuously changed by the control device 27 in the vicinity of the transition point pt2 from the approach path PS1 to the shape path PS2 and in the vicinity of the transition point pt3 from the shape path PS2 to the retreat path PS3. To be controlled. For this reason, in the vicinity of the transition points pt2 and pt3, the acceleration acting in the normal direction of the machining surface W1a changes continuously without abrupt change. Therefore, unlike the conventional machining method shown in FIGS. 8 and 9, a large control error does not occur due to a rapid change in acceleration, and the uncut remaining projection W1b does not occur on the machining surface W1a.
[0032]
At the time of pocket machining of the workpiece W, the control device 27 causes the transition point pt3 from the shape path PS2 to the retreat path PS3 to be closer to the front side than the transition point pt2 from the approach path PS1 to the shape path PS2. Be controlled. As a result, in the vicinity of one round of the shape path PS2, the shape path PS2 is finished early and transferred to the retreat path PS3 before the cutting reaction force is reduced due to the reduction of the cutting shaving. Therefore, unlike the conventional machining method shown in FIGS. 8 and 9, the excessively cut recess W1c does not occur on the machined surface W1a with the reduction of the cutting reaction force due to the reduction of the cutting surface. Therefore, the pocket processing of the inner peripheral processing surface W1a of the pocket portion W1 of the workpiece W can be performed with high efficiency and high accuracy by the shape path PS2 for approximately one round.
[0033]
Furthermore, in this end mill processing apparatus, as shown in FIG. 6A, when the outer peripheral processing surface W2a of the chevron W2 formed on the side surface of the workpiece W is processed by the end mill 25, the input is performed. The device 29 selects the mode of processing. Thereafter, when the operation of the apparatus is started, the position of the end mill 25 with respect to the processing surface W2a is stored in the memory 28 as shown in FIG. 6B while the end mill 25 is rotated by the control of the control device 27. Based on the data, the approach path PS1, the shape path PS2, and the save path PS3 are shifted in this order. Then, while the end mill 25 makes one round along the shape path PS2, the outer peripheral processing surface W2a of the workpiece W is subjected to yama processing.
[0034]
Also in the case of this processing, as in the case of the pocket processing, the control device 27 controls the transition point pt2 from the approach path PS1 to the shape path PS2 and the transition point pt3 from the shape path PS2 to the retreat path PS3. The curvature of the movement trajectory of the end mill 25 is continuously changed. Similarly to the case of pocket machining, the transition point pt3 from the shape path PS2 to the retreat path PS3 is controlled to be closer to the front side than the transition point pt2 from the approach path PS1 to the shape path PS2. Therefore, in the vicinity of these transition points pt2, pt3, there is no occurrence of uncut protrusions or excessively cut recesses on the outer peripheral processed surface W2a, and the outer peripheral processed surface W2a is formed by the shape path PS2 for approximately one turn. High-efficiency and high-precision processing can be performed. Note that the approach path PS1 in the case of YAMA processing has a locus that continuously changes the curvature to the curvature of the shape path PS2 at the transition point pt2 after drawing a straight locus as shown by a solid line in FIG. 6B. Draw. The retreat path PS3 draws a straight locus after drawing a curvature that continuously changes from the curvature of the shape path at the transition point pt3.
[0035]
Therefore, according to this embodiment, the following effects can be obtained.
(1) In this end mill processing apparatus, the position of the end mill 25 with respect to the processing surfaces W1a and W2a of the workpiece W is set to approach path PS1 approaching the processing surfaces W1a and W2a, shape path PS2 along the processing surfaces W1a and W2a, and The retreat path PS3 that is spaced apart from the processing surfaces W1a and W2a is sequentially shifted. When machining the machining surfaces W1a and W2a, the curvature is continuously changed from the approach path PS1 to the shape path PS2 under the control of the control device 27.
[0036]
For this reason, when moving from the approach path PS1 to the shape path PS2, the acceleration acting in the normal direction of the processed surfaces W1a and W2a changes continuously without abrupt change. Therefore, it is possible to prevent a large control error from occurring due to a rapid change in acceleration and to generate the remaining uncut protrusion W1b on the processed surfaces W1a and W2a, thereby improving the processing accuracy. Further, since the shape path PS2 is performed only once, the processing time is not increased as in the case where the shape path PS2 is performed twice, and a predetermined processing efficiency can be maintained.
[0037]
(2) In this end mill processing apparatus, the curvature is continuously changed by the control of the control device 27 even from the shape path PS2 to the retreat path PS3. For this reason, even during the transition from the shape path PS2 to the retreat path PS3, the acceleration acting in the normal direction of the processed surfaces W1a and W2a changes continuously without abrupt change. Therefore, it is possible to reliably suppress the occurrence of the uncut protrusion W1b on the processed surfaces W1a and W2a, and the processing accuracy can be further improved.
[0038]
(3) In this end mill processing apparatus, the transition point pt3 from the shape path PS2 to the retreat path PS3 is made earlier than the transition point pt2 from the approach path PS1 to the shape path PS2 under the control of the control device 27. ing. Therefore, in the vicinity of one round of the shape path PS2, it is possible to shift from the shape path PS2 to the retreat path PS3 prior to the reduction of the cutting reaction force due to the reduction of the cutting scissors. Therefore, it is possible to suppress the occurrence of the excessively cut recess W1c on the processed surfaces W1a and W2a as the cutting reaction force is reduced, and the processing accuracy can be further improved.
[0039]
(4) In this end mill processing apparatus, as processing of the processing surfaces W1a and W2a, pocket processing of the inner peripheral processing surface W1a of the pocket portion W1 formed on the workpiece W and Yama of the outer peripheral processing surface W2a of the chevron portion W2 Either one of the processing and the processing is selected. For this reason, in the processing selection state, the pocket processing of the inner peripheral processing surface W1a of the pocket portion W1 or the Yama processing of the outer peripheral processing surface W2a of the chevron portion W2 can be efficiently performed with high accuracy.
[0040]
(Example of change)
Note that this embodiment can also be embodied in the following forms.
[0041]
That is, the curvature radii of the approach path PS1 and the evacuation path PS3 are made larger or smaller than those in the embodiment. As shown by a solid line in FIG. 6B, the approach path PS1 in the case of YAMA processing is drawn as a tangent line that passes through the transition point pt2 after drawing an arc locus or linear locus having a smaller radius of curvature than the shape path PS2. Draw an approximate curvature trajectory. Further, the retreat path PS3 draws an arc locus or straight line locus having a smaller radius of curvature than the shape path PS2 after drawing a locus of curvature approximated to a tangent line passing through the transition point pt3.
[0045]
【The invention's effect】
As described above, as exemplified in the embodiment, in the present invention, when pocket machining or yama machining is performed on the workpiece by the end mill, it is possible to suppress the occurrence of uncut protrusions and overcut recesses on the machining surface. And the processing accuracy can be improved.
[Brief description of the drawings]
FIG. 1 is a front view showing an end mill processing apparatus according to an embodiment.
FIG. 2 is a block diagram showing a circuit configuration of an end mill processing apparatus.
FIG. 3 is an explanatory diagram showing a machining state when pocket machining is performed.
FIGS. 4A to 4E are explanatory diagrams showing changes in curvature between an approach path and a shape path. FIGS.
FIG. 5 is an explanatory diagram showing the timing of transition from a shape path to a save path.
FIG. 6A is a simplified diagram showing a machining state in the case of performing a yam machining, and FIG. 6B is an explanatory diagram showing each pass.
7A is a cross-sectional view showing a pocket processing state of a conventional end mill processing apparatus, and FIG. 7B is an explanatory view showing a conventional pass.
FIG. 8 is also an explanatory diagram of a pocket processing state.
FIG. 9 is a partial side view of the workpiece showing the machining result at the time of pocket machining.
[Explanation of symbols]
25 ... End mill, 27 ... Control device as control means, 28 ... Memory, 29 ... Input device, W ... Workpiece, W1 ... Pocket part, W1a ... Inner peripheral surface, W1b ... Projection, W1c ... Recess, W2 ... Yamagata Part, W2a ... outer peripheral machining surface, PS1 ... approach path, PS2 ... shape pass, PS3 ... retraction path, pt1 ... retraction point, pt2, tp3 ... transition point.

Claims (1)

The position of the end mill with respect to the circular machining surface of the workpiece is shifted in order according to the approach path approaching the machining surface, the shape path along the machining surface, and the retract path away from the machining surface, and the workpiece machining surface is cut. In the end mill processing device
Control so that the curvature of the movement path of the end mill continuously changes from the approach path to the shape path, and control so that the curvature of the movement path of the end mill continuously changes from the shape path to the retreat path, An end mill processing apparatus comprising a control means for controlling a transition point from the shape path to the retreat path so as to be closer to the front side than the transition point from the approach path to the shape path.

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