JPH0241846A - Working method for scroll shape - Google Patents

Abstract

PURPOSE:To perform a highly accurate working without any residual cutting by adequately controlling a cutting speed or the rotary speed of a work according to the variation in the contact length of a work tool and the curvature of a scroll wall face in cutting the scroll wall face of the work. CONSTITUTION:On a work W in a scroll shape, the contact length l of a work tool to the work W is operated from the values of the distance X from the basic circle center of an involute curve to the tool center of the work tool, a work azimuth C, work tool diameter D and work cutting amt. L first. According to the contact length l being elongated with the curvature of a scroll wall face being changed the cutting speed of the work tool or the rotating speed of the work is controlled so as to delay it. Namely, the radius of curvature of the scroll wall face is reduced according to the progress in cutting, the contact length l of the work tool for the work W is elongated, even in case of the cutting resistance being increased, the contact time of the work tool with the work W is elongated by the part thereof and no residual cutting is made to cause.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is used in compressors and the like. The present invention relates to a scroll-shaped processing method for cutting a wall surface of a single scroll-shaped scroll formed by an involute curve.

(Prior Art) In recent years, positive displacement spiral fluid machines that move fluid through swirling motion or orbital motion have been developed and put into practical use as compressors used in air conditioners and the like.

This positive displacement spiral fluid machine consists of a pair of disks (mirror-symmetrical to each other) each having a scroll-shaped wall of a predetermined height, which are offset by 180 degrees, and the spiral walls are brought into contact with each other. It rotates relative to each other while maintaining the angular relationship, resulting in smooth operation, low noise, low vibration, and
It is attracting attention because it has many excellent features such as being able to rotate at high speed and being highly efficient.

As the spiral curve forming the scroll shape, an involute curve is used for geometrical perfection.

Machining of such a scroll shape involves replacing the relational expression of the involute curve with the coordinate values of the orthogonal coordinate system, inputting these coordinate values into the NC machine tool of the X-Y coordinate system, and connecting the processing tool and the scroll part (workpiece). This can be done by relative movement of the
There is a problem in that the error in the movement trajectory of the machining tool becomes large in the center of the scroll component due to the follow-up delay of the servo of the C device, making it impossible to increase the feed rate. For this reason, for example, as disclosed in Japanese Patent Application Laid-Open No. 62-88507, the center position of the processing tool is moved on a straight line tangent to the base circle of the involute curve of the scroll component, and the center position of the processing tool is moved in synchronization with the base circle of the scroll component. By rotating and machining the involute curve with the base circle center as the rotation center, the moving direction of the machining tool is set to the normal direction of the involute curve, making it possible to perform high-speed and high-precision machining. The processing method is known.

(Problems to be Solved by the Invention) Incidentally, the radius of curvature of the scroll wall surface of the workpiece gradually becomes smaller toward the center of the workpiece.

As the radius of curvature of the scroll wall becomes smaller in this way,
The contact length of the machining tool with respect to the workpiece becomes longer, the contact resistance increases, and as a result, uncut parts are generated and the amount of cutting cannot reach the target value. Therefore, even if the machining accuracy is improved as described above, the above method does not take into account the contact resistance of the machining tool to the workpiece, so in reality, the radius of curvature of the scroll wall surface is reduced. The current situation is that the cutting accuracy deteriorates as a result of this, making it impossible to accurately and reliably cut the scroll shape.

The present invention has been made in view of these points, and its purpose is to appropriately control the cutting speed of a processing tool or the rotational speed of a workpiece in accordance with changes in the curvature of the scroll wall surface of the workpiece. To consistently and accurately cut a scroll wall surface whose curvature changes from moment to moment.

(Means for Solving the Problems) In order to achieve the above object, the solving means of the present invention is such that a scroll wall surface of a scroll-shaped workpiece rotatably supported on a workpiece stand and formed by an involute curve is supported on a tool stand. As a method of machining a scroll 1-shape by cutting with a machining tool that is The contact length of the processing tool with respect to the workpiece is calculated, and the cutting speed of the processing tool or the rotational speed of the workpiece is controlled to become slower as the contact length becomes longer.

(Function) With the above configuration, in the method of the present invention, during cutting of the scroll wall surface of a scroll-shaped workpiece formed by an involute curve, the contact length of the processing tool with the workpiece is It is calculated from the distance to the tool center of the processing tool, the workpiece rotation angle, the processing tool diameter, and the workpiece depth of cut, and the cutting speed of the processing tool or the rotational speed of the workpiece is controlled to become slower as the contact length becomes longer. Ru.

From this, as the cutting progresses, the radius of curvature of the scroll wall surface gradually decreases, and even if the contact length of the processing tool with the workpiece becomes longer and the cutting resistance increases, the contact time of the processing tool with the workpiece increases by that amount. It is made long and leaves no uncut parts, so that the scroll wall surface, whose curvature changes from time to time, can always be precisely and reliably cut.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 3 schematically shows the apparatus main body 1 of a scroll-shaped processing apparatus to which the method of the present invention is applied. First, prior to explaining the method of the present invention, the structure of the apparatus main body 1 will be explained. The device main body 1 includes a work table 3 placed on one end side of the bed 2.
and a tool stand 4 disposed on the other end side of the bed 2, on the work stand 3, a work spindle 5 is arranged rotatably by a first servo motor 6, and is formed by an involute curve. The work table 3 is held with a scroll-shaped work (not shown) held on the work spindle 5.
It is designed to be rotatably supported. On the other hand, the tool stand 4 has a plurality of (three in the figure) tool spindles 7. 7
．． 7 are arranged to be rotatable by a second servo motor 8, and a processing tool 9 for cutting the scroll wall surface of the workpiece is rotatably installed on each tool main shaft 7.

The tool stand 4 is movably supported by the X-axis table 10, and is moved by a third servo motor 11 in a horizontal direction perpendicular to the workpiece main shaft 5 (workpiece rotation center line). Further, the X-axis table 10 is movably supported by a Z-axis table 12 fixed to the upper surface of the bed 2, and is moved in the axial direction of the workpiece spindle 5 by a fourth servo motor 13. .

In addition, the first to fourth servo motors 6.8 of the device main body 1,
As shown in FIG. 1, 11 and 13 are each driven and controlled based on a control program of a control device 14 as a control means.

Next, to explain how to cut the scroll wall surface of a scroll-shaped workpiece formed by an involute curve using the processing apparatus configured as described above, first, cut the involute part and circular arc part of the desired involute curve. and the data of the X-Y coordinate system in NC language of the straight line part are inputted to the control device 14, and the first to third
NC data conversion calculation units 15 to 17 perform conversion calculations into NC data in the X-C polar coordinate system according to preprogrammed calculation formulas.

To explain the data conversion in the first to third NC data conversion calculation units 15 to 17 using the involute unit as an example, the data conversion is performed by the following calculation formulas (11, (2). That is, FIG. Based on the following, a: Base circle radius of the involute curve θ: Involute angle V: Angle from the X-axis to the involute start position D = tool cutting edge radius, then X-axis direction position (center of base circle The distance f4) from ) is + in the positive direction of the involute curve from the X axis, and - in the negative direction.The sign (±) of D (tool cutting edge radius) differs depending on whether the scroll wall surface to be machined is the inner or outer circumference. , in the case of the inner peripheral wall, is 11, and in the case of the outer peripheral wall, it is 10. In this embodiment, the case where the inner peripheral wall is cut is shown.

Also, the distance X of the workpiece W from the center of the base circle to the center of the processing tool 9 determined by the above formula (1)
The rotation angle C from the axis is C-e-j a n-1[(a (θ+V)+D)/
a...(2) Calculate.

Meanwhile, in parallel with the above NC data conversion, the X-Y coordinate system data in the NC language of the involute part, arc part and straight part of the above involute curve is input to the first to third contact length calculation units 18 to 20. Then, the first to third contact length calculation units 18 to 20 calculate each contact length Ω.

The calculations in the first to third contact length calculation sections 18 to 20 will be explained using an involute section as an example.

Here, L: workpiece depth R; virtual calculation point C1-〇+ -tan-' [ia (e+ +v
) +Ll/a] C2=/C+ -C/R-X2+X) 2-2X-XH・cos C2 Then, when the relationship between R and D becomes D2≦R, the calculation is finished and the The contact length Ω of the processing tool 9 is determined based on the following relational expression.

C3-CO5t(X +D -X+2)/2DX) C4-t a n-' [a/ (a (θ+V) +
Dl] C5-π-(C3+C,+) Ω-D-05 The sign (±) of L (workpiece depth of cut) differs depending on whether the scroll wall surface to be machined is the inner or outer circumference. -, and in the case of the outer peripheral wall, it is 10.

Next, after dividing the NC data and contact length data obtained in this way and performing interpolation calculations to obtain the optimal trajectory, the X, axis position (X-axis direction movement amount), C-axis rotation angle, and The distribution time T is calculated, and the obtained calculation result is input to the tool cutting speed control section 21. Then, the tool cutting speed control section 21 calculates and adjusts the distribution time T of the NC data so that it increases as the contact length g becomes longer based on the contact length data.
- After inputting the C-T data to the NC data 7 section 22, the pulse distribution section 23 distributes the pulses, and
Drive control of servo motors 6.8, 11.13. Thereby, the cutting speed of the processing tool 9 is controlled to become slower as the contact length g of the processing tool 9 with the workpiece W becomes longer.

Therefore, the radius of curvature of the scroll wall surface of the workpiece W gradually becomes smaller as the cutting progresses, and the contact length g
Even if the cutting force increases due to the increase in the cutting force, the contact time of the machining tool 9 with the workpiece W increases accordingly, and no uncut material is left uncut.
The scroll wall surface can be machined consistently and accurately.

In the above embodiment, the plunge speed of the machining tool 9 is controlled to become slower as the contact length g of the machining tool 9 with respect to the workpiece W becomes longer; however, the present invention is not limited to this, and for example, may be controlled to become slower as the contact length g becomes longer.

(Effects of the Invention) As explained above, according to the method of the present invention, when cutting and pressurizing the scroll wall surface of a scroll-shaped workpiece formed by an involute curve, the contact length of the processing tool with the workpiece is Calculate from the distance from the base circle center of the involute curve to the tool center of the above processing tool, workpiece rotation angle, processing tool diameter, and workpiece depth of cut, and calculate whether the cutting speed of the above processing tool or the rotational speed of the workpiece or the above contact length is longer. control so that it becomes slower as the speed increases. Therefore, the scroll wall surface of the workpiece whose curvature changes from moment to moment can be machined with high precision and reliability regardless of the contact length of the processing tool.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a control block diagram showing a control system for a scroll-shaped processing device, and FIG.
The figure is an explanatory diagram for calculating the contact length of a machining tool that touches a workpiece by χ·l, and FIG. 3 is a perspective view of the main body of the machining device. 3... Work stand, 4... Tool stand, 9... Machining tool, X... Distance from the center of the base circle of the involute part to the tool center of the processing tool, C... Work rotation angle, D...・・・
Tool tip radius, L...workpiece depth of cut, g...contact length, W...workpiece.

Claims (1)

[Claims] (1) A scroll-shaped processing method in which a scroll wall surface of a scroll-shaped workpiece rotatably supported on a workpiece stand and formed by an involute curve is cut by a processing tool supported on a tool stand, the scroll-shaped workpiece being rotatably supported by an involute curve. The contact length of the machining tool with the workpiece is calculated from the distance from the center of the basic circle of the curve to the tool center of the machining tool, the workpiece rotation angle, the machining tool diameter, and the depth of cut of the workpiece, and the cutting speed of the machining tool or the rotation of the workpiece is calculated. A method for processing a scroll shape, characterized in that the speed is controlled to become slower as the contact length becomes longer.