JP2698764B2 - Processing method of scroll wrap - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of processing a scroll wrap, and more particularly to a method of scrolling using an NC (numerical control) machine such as a machining center. risk of such involute spiral grooves constituting a compression chamber of the compressor
Suitable scroll La to precision machining the roll wrap
The present invention relates to a method of processing a tip . 2. Description of the Related Art First, as an example of a workpiece to which the present invention is applied, a scroll member constituting a compression chamber of a scroll compressor is taken up, and a conventional processing method thereof will be described with reference to FIGS. Will be explained. Here, FIG. 4 is a perspective view of female and male scrolls relating to a workpiece, FIG. 5 is a plan view as viewed from the direction indicated by an arrow A in FIG. 4, and FIGS. 6 and 7 are diagrams for explaining a conventional processing method of a scroll member. FIG. In FIGS. 4 and 5, 1 is a male scroll,
Reference numeral 2 denotes a female scroll, and the scroll wrap 5 of the protrusion 3 of the male scroll 1 and the scroll wrap 6 of the recess 4 of the female scroll 2 are both U-shaped in the cross section of the spiral groove formed by the wrap. The helix is of involute shape. The male scroll 1 and the female scroll 2 have a structure in which the respective scroll wraps 5 and 6 are opposed to each other and are relatively peristaltic to compress the pressure medium. Conventionally, such an involute scroll wrap has been cut by so-called "XY machining" by attaching a workpiece to an XY table of a vertical or horizontal machining center using an end mill tool. In this case, as shown in FIGS. 6 and 7, for example, when the scroll wrap 5 of the male scroll 1 is processed using an end mill 7 having a diameter D, a contact point P between the outer periphery of the end mill 7 and the involute scroll wrap 5 is formed. Is the center O of the male scroll 1 and the center Q of the end mill 7.
Does not exist on the line connecting, and the declination θ between OQ and PQ
Changes with the processing position of the scroll wrap 5 one by one. For example, as shown in FIG. 6, when the outer wall of the scroll wrap 5 is machined, the deviation angle between OQ and PQ is θ, but when the machining of the outer wall is finished, the center of the end mill 7 is Q. ′, And the declination θ ′ formed between the outer periphery of the end mill 7 and the contact point P ′ between the scroll wrap 5 greatly changes compared to θ. Also, as shown in FIG. 7, at the stage of machining the inner wall of the scroll wrap, at the position of the center Q ″ of the end mill 7, the deviation angle θ ″ between the contact point P ″ between the outer periphery of the end mill 7 and the inner wall of the scroll wrap is [0006] Therefore, in order to machine the male scroll 1 on the XY table of the machining center, a locus of the end mill center Q different from a predetermined involute shape is drawn. Of course, in the past, such a desired involute shape was determined by using N points of a number of point groups of XY coordinates.
If given as C data , the center locus of the end mill is automatically calculated by the NC control system of the machining center,
It was also become possible to process. However, XY on such an XY table
In machining using a coordinate system, the number of input points of NC data is large.
In addition , it is assumed that the value of the end mill diameter is input to the NC control system. Accordingly, different diameter of the end mill, but inputs the value to the respective NC control system, in which case the number of XY coordinates by calculating in advance the tool path
Must be input as NC data of the point cloud . In particular, when the involute shape accuracy is severe, it is essential to improve the reading accuracy of the end mill diameter. In this conventional method, even if the end mill diameter is accurately read, if the end mill is mounted eccentrically with respect to the main shaft of the machining center, the end mill is machined as if an apparently larger end mill was used. The shape, especially the thickness T thereof is different from a predetermined value, and it is necessary to correct the tool dimensions. Since the inner and outer walls of the scroll wrap are processed by such a method, the thickness T of the scroll wrap actually causes an error approximately twice as large as the reading error of the end mill diameter. The conventional involute shape processing method using a machining center having an XY table has been described above. However, even when a rotary table is mounted on an XY table and a workpiece is set on the rotary table to perform processing, Since the center of the end mill is moved on the OQ with respect to the rotation of the rotary table, the same error as described above occurs, and it is difficult to process an involute shape with high accuracy. As mentioned above, the problems of the prior art have been pointed out by taking the male scroll as an example, but the female scroll also has exactly the same problem. Therefore, the linear motion of the moving table and the rotor
NC control linked to the rotational movement of the retable in a proportional relationship
While processing the involute shape, the so-called “R
The momentum to develop “θ processing” has come. Other prior art
JP-A-57-15610 discloses a scroll unit.
Rotate the product around the center of the base circle of its involute curve
As well as turning the machining tool
By moving on a straight line tangent to the base circle of the curve
To process scroll parts
You. However, Japanese Patent Application Laid-Open No. 57-15610 discloses
Scroll processing device, a rotating processing table and X
The moving table that moves straight in the direction
The inner wall surface and outer wall surface of the scroll wrap are sequentially
High precision machining is not considered
Was. SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a simple program control of an NC processing machine to control a contact point (processing) between a processing tool and an involute curve. to eliminate the trajectory error of the tool occurs with declination of the point), the involute of the workpiece
An object of the present invention is to provide a scroll wrap processing method that realizes a series of processing of an inner wall surface and an outer wall surface with high precision. [0012] In order to achieve the above object, a method of processing a scroll wrap according to the present invention comprises a table capable of moving linearly, a rotary table and a rotatable rotary table.
Machining with a cable and a rotating spindle that holds the tool
Means for processing a workpiece having a scroll wrap
The inner and outer wall surfaces of the scroll wrap are curved involute shape
A method for processing the workpiece into a row.
With the tally table rotated, the NC processing means
The table is moved straight based on the synchronization command of the control system.
The tool held on the rotating spindle is
The above-mentioned swath is formed on the tangent of the first base circle of the involute shape.
The first base circle along one wall surface of the crawl wrap
Relative to the workpiece in a direction approaching the center of
To move the first wrap on one wall surface of the scroll wrap.
Machining a convoluted curved surface and controlling the NC machining means
Between the tool and the workpiece based on a synchronization command of the control system.
By displacing the relative positions, the tool is moved to the second
Move to the starting point of machining the
With the rotation direction of the rotary table reversed, the N
The table based on a synchronization command of a control system of the C processing means.
Is held by the rotating spindle by moving the
Tool that has been in contact with the involute-shaped second base circle.
On the line along the other wall of the scroll wrap
In the direction away from the center of the second base circle
Relative to the other side of the scroll wrap
Processing the second involute curved wall
To process the scroll wrap by
It is. According to the present invention, a workpiece to be processed into an involute shape is fixed to the center of the rotary table on a rotary table rotatably mounted on a moving table that moves linearly. An end mill is mounted on a rotating spindle that is substantially vertical to the surface, and the end surface of the end mill is brought into contact with the processing surface of the workpiece so as to be orthogonal to the tangent to the base circle of the involute of the workpiece, and the center of the end mill but with linearly moving the moving table to move tangent on the involute base circle, the rotary table is rotated so that its angle of rotation is interlocked with a constant proportional relationship between the feed amount of the moving table
Have . The idea of developing the present invention is that the XY table and the rotary table are adjusted so that the contact angle between the involute-shaped processing surface and the outer periphery of the end mill is always constant, taking advantage of the feature that the workpiece is involute. To control. That is, X table or Y
Controlling the NC machine with a simple program input by setting the feed direction of one of the tables to the tangent direction of the base circle of the involute and making the feed speed completely proportional to the rotation speed of the rotary table The method is simplified and the processing accuracy is improved. An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an explanatory view showing a tool path in an involute shape processing method according to an embodiment of the present invention, FIG. 2 is an explanatory view showing the principle of involute shape processing, and FIG. 3 is a processing machine for performing the processing of FIG. It is an external appearance perspective view of. The processing machine shown in FIG. 3 has substantially the same configuration as a general machining center, and has a N
An X-axis table 10 related to a C-controllable moving table and a Y-axis table 11 related to a moving table are provided.
Furthermore, a rotary table 12 which can also be NC controlled is provided thereon. On this rotary table 12, the male scroll 1 which is a workpiece is chucked with the same axis as the rotary table. On the other hand, a spindle head 14 slidable by NC in the axial direction of the rotary table 12 slides on the column 13 fixed integrally with the bed 9. There is a rotatable main shaft 15 having a center direction.
5 is chucked with an end mill 7 relating to a tool. These motion systems, that is, the X table 10
And linear motion of Y table 11, rotary table 1
2, the linear motion of the spindle head 14 and the rotational motion of the spindle 15 can be controlled by an NC control device (not shown). This embodiment relates to the NC control of the involute shape machining of the machining center having such a configuration. Next, the principle of the involute shape machining will be described with reference to FIG. The workpiece is a scroll wrap 5 associated with the scroll member of the male scroll 1 and has two involute curves 5a and 5b whose phases are shifted from each other by the same base circle.
An inner wall is formed. In this case, as shown in FIG. 2, the center of each of the two involute curves 5a and 5b is O, and the radius of the base circle 20 is a (see FIG. 1). An arbitrary tangent line 21 drawn from the base circle 20 is always orthogonal to the involute curves 5a and 5b. This means that if the center of the end mill 7 is moved on the tangent to the base circle of the involute, the contact point P between the end mill and the involute is on the tangent of the base circle, as described in the prior art. This means that there is no need to perform a complicated correction in consideration of an error caused by a certain value of the argument θ or θ ″ (see FIGS. 6 and 7) of the contact point between the end mill and the involute curve.
That is, as shown in FIG. 1, an arbitrary cutting line 21 to the above-mentioned involute base circle 20 is defined as the X axis of the machining center, that is, the straight traveling direction of the X table, and the center Q of the end mill 7 is on this X axis. The synchronization command may be given to the NC control system so that the rotation angle of the male scroll 1 as the workpiece and the position of the end mill 7 in the X-axis direction are always proportional. This can be controlled by simple program input to the NC controller. Therefore, the end mill 7 mounted on the spindle 15
Is made to contact the outer wall of the involute curve 5a which is the processing surface so as to be orthogonal to the tangent line 21 of the base circle 20 of the involute of the male scroll 1 which is the workpiece, and the tangent line 21 and the X axis The straight traveling direction of the table 10 is matched. Then, while moving the X-axis table 10 straight so that the center Q of the end mill 7 moves inward on the tangent line 21, that is, in a direction approaching the center of the base circle 20,
The outer wall of the involute curve 5a is machined by rotating the rotary table 12 in conjunction with the rotation amount of the rotary table in a fixed proportional relationship with the feed amount of the X-axis table 10. After finishing the outer wall, the rotary table 1
By rotating the end mill 2 in reverse, the rotation of the male scroll 1 is reversed, and the phase of the rotation angle is shifted by a predetermined amount to position the end mill 7 at the start position of the involute curve 5b. Here, the predetermined amount for shifting the phase is an amount uniquely determined by the diameter of the end mill 7, the diameter of the base circle 20 of the involute, and the thickness T of the involute trap.
More specifically, it is an angle (radian) obtained by dividing the sum of the end mill diameter, the thickness T of the involute trap, and the radius a of the base circle 20. Next, in synchronization with the reverse rotation of the rotary table 12, the X-axis table 10 is returned in the returning direction so as to move the end mill center Q in the outward direction on the tangent line 21, that is, in the direction away from the center of the base circle 20. The inner wall of the involute curve 5b is processed by moving straight. In other words,
X-axis table 10 that moves straight so that the center of end mill 7 moves on tangent line 21 of involute base circle 20
Is used to perform forward and backward movements by reversing the straight traveling direction between the processing of the outer wall and the processing of the inner wall of the scroll wrap 5,
The rotary table 12 operates so as to change the direction of rotation forward and backward in conjunction with the forward and backward movements of the X-axis table. By doing so, the involute curve 5
No error correction due to the declination θ ″ (see FIG. 7) is required for the inner wall of the scroll b.
Series of machining, relative position change of end mill, inner wall machining
The processes are performed sequentially and continuously on the same processing machine shown in FIG.
Can be. Even when the above-described involute shape machining method is employed, a tool dimensional error ε such as an eccentricity when the end mill 7 is attached or a deflection error of the end mill causes an error of 2ε in the thickness T of the scroll wrap 5. Therefore, when the thickness accuracy of the involute-shaped scroll wrap is more strictly required, the tool trajectory described below may be traced. As shown in FIG. 1, the center Q of the end mill 7 is
Is positioned on the tangent line 21 of the base circle 20 of the involute, and the blade surface of the end mill 7 is brought into contact with the outer wall of the involute curve 5a which is the processing surface so as to be orthogonal to the tangent line 21. Then, the straight traveling direction of the X-axis table 10 is made to coincide with the tangent 21 of the base circle 20. Then, the X-axis table 10 is moved straight (first straight movement) so that the center Q of the end mill 7 moves inward on the tangent line 21, and the rotary table 12 is rotated by the rotation angle of the X-axis table 10. Involute curve 5a by rotating in conjunction with the feed amount in a fixed proportional relationship
The outer wall of When the processing of the outer wall is completed, the center Q of the end mill 7 is aligned with the diameter 2a of the base circle 20 at the center of the male scroll 1.
Only, the Y-axis table 11 is moved so as to move in a direction orthogonal to the first straight traveling direction. Next, in synchronization with the reverse rotation of the rotary table 12, the base circle 20 shown in FIG.
The X-axis table 10 is caused to move in the second direction in the same direction as the first direction so as to move the end mill center Q in the outward direction on the tangent line 22 of the involute curve 5b.
And the machining of the male scroll 1 is completed. By doing so, the outside of the scroll wrap
A series of wall processing, end mill relative position change, and inner wall processing
Are performed sequentially and continuously on the same processing machine shown in FIG.
Direction of the cutting force applied to the end mill
It is clear that the construction and the inner wall processing are the same. Ma
In addition , errors in the scroll shape due to elastic deformation of the end mill 7 and the scroll wrap 5 due to the cutting force load, etc.
5 can easily corrected by Rukoto is slightly inclined, it is possible to improve the thickness accuracy of the scroll wrap 5 of involute shape. In the above-described embodiment, the processing example is described as the male scroll 1 as the workpiece.
Needless to say, the processing of the female scroll 2 can be performed in exactly the same manner. Further, in the above-described embodiment, an example in which a machining center is used as a processing machine has been described. Further, the same effect can be obtained by processing the inner wall of the involute shape in the same manner and then processing the outer wall. Furthermore, in the above-described embodiment, the processing machine is a vertical machining center, but it may be a horizontal machining center with the main shaft center being horizontal. In this case, there is an advantage that chips are easily removed, and the surface roughness of the processed surface is improved. When the thickness T of the scroll wrap is not constant and consists of two involute curves, there are two base circles. When shifting to, at the center of the workpiece, an extra shift is made in the Y direction by the difference between the two base circles so as to follow the latter half of the tool trajectory, and this can be realized. As described above, the trajectory error of the tool caused by the declination of the contact point (processing point) between the processing tool and the involute curve is eliminated by the simple program control of the NC processing machine. The inner wall of the workpiece
Scroll that realizes high-precision series of processing of surface and outer wall
A method for processing lulap can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram showing a tool trajectory in an involute shape machining apparatus according to one embodiment of the present invention. FIG. 2 is an explanatory diagram showing the principle of involute shape processing. FIG. 3 is an external perspective view of a processing apparatus according to the present invention. FIG. 4 is a perspective view of female and male scrolls relating to a workpiece. FIG. 5 is a plan view as viewed from the direction indicated by the arrow A in FIG. 4; FIG. 6 is an explanatory view for explaining a conventional processing method of a scroll member. FIG. 7 is an explanatory diagram for explaining a conventional processing method of a scroll member. [Description of Signs] 1 ... Male scroll, 2 ... Female scroll, 5 ... Scroll wrap, 5a, 5b ... Involute curve, 7 ... End mill, 10 ... X axis table, 11 ... Y axis table, 12
... Rotary table, 15 ... Spindle, 20 ... Base circle, 2
1,22 ... tangent line.

Claims (1)

(57) [Claims] A linearly movable table and a rotatable rotary
Machining with a cable and a rotating spindle that holds the tool
Means for processing a workpiece having a scroll wrap
The inner and outer wall surfaces of the scroll wrap are curved involute shape
Machining to a method and to rotate the rotary table mounting the workpiece
In the state, based on the synchronization command of the control system of the NC machining means,
The table is moved in a straight line to
The tool held by the spindle is moved to the involute shape
One wall of the scroll wrap on a tangent to the base circle
In a direction approaching the center of the first base circle along the plane
The scroller is moved relatively to the workpiece.
Add a first involute curved surface to one wall of the
And Engineering, the engineering based on the synchronization command of the control system of the NC processing means
By shifting the relative position of the tool and the workpiece.
The tool is used for machining a second involute curved surface.
Moved to the starting point, with the rotation direction of the rotary table reversed,
Based on the synchronization command of the control system of the NC processing means,
By moving the cable straight, it is held on the rotating spindle.
Holding the held tool on the second base of the involute shape
On the tangent of the circle along the other wall of the scroll wrap
In the direction away from the center of the second base circle.
The scroll wrap is moved relatively to the workpiece
A second involute-shaped curved surface on the other wall surface of
To process the scroll wrap by
Scroll wrap processing method. 2. Place the tool on the scroll wrap
Of the second base circle on the tangent line of the second base circle
Relative to the workpiece in a direction away from the center
Moving the tool forward on the scroll wrap
The first base circle of the involute shape is tangent to the first base circle.
In the direction approaching the center of the base circle
Japanese to be moved in the same direction as the direction of moving pairs to
The method for processing a scroll wrap according to claim 1. 3. Place the tool on the scroll wrap
Of the second base circle on the tangent line of the second base circle
Relative to the workpiece in a direction away from the center
Moving the tool forward on the scroll wrap
The first base circle of the involute shape is tangent to the first base circle.
In the direction approaching the center of the base circle
Move in the opposite direction to the opposite direction.
The method for processing a scroll wrap according to claim 1.