JP4183058B2 - Blade cutting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for cutting blades of a turbine or a compressor having a very small thickness .
[0002]
[Prior art]
When machining a turbine or compressor blade, which is a very thin member, by machining, if the cutting allowance is large and the cutting resistance is large, the blade itself deforms and escapes due to the cutting resistance, causing so-called chatter vibration. become unable.
[0003]
[Problems to be solved by the invention]
For this reason, it has been considered that such blade cutting is impossible in the past, and it has been necessary to manufacture by repeatedly processing from roughing to finishing by reducing the cutting allowance. In this case, in the case of a blade having a complicated shape such as a thin blade of a turbine or a compressor, a plurality of mounting jigs 2 for supporting the blade 1 being processed are prepared as shown in FIG. The front and back of the thin blade must be alternately and repeatedly scraped little by little using an end mill 3 or the like. For this reason, the machining of such a blade requires a large number of jigs, and the machining time is long, resulting in a problem that the machining cost is high.
[0004]
The present invention has been developed to solve such problems. That is, an object of the present invention is to provide a blade cutting method capable of cutting a blade having a very thin thickness without repeating the machining from roughing to finishing without using a special jig. Is to provide.
[0005]
[Means for Solving the Problems]
According to the present invention, a material having a sufficient allowance for a turbine or compressor blade is prepared, an end mill that does not interfere with the curvature of the blade recess is prepared, and the bottom surface of the end mill is flat,
One end of the material in the longitudinal direction is supported by a fixture, and the end mill has a portion that becomes the antinode of the wing and a portion of the antinode in a state in which the rotation axis of the end mill is oriented perpendicular to the processing surface of the wing. Cutting the material once from the other end in the longitudinal direction to the one end in the longitudinal direction while rotating around the material so as to alternately pass through the wing portions on the opposite side Thus, there is provided a blade cutting method characterized in that the material is made into a complete shape of the blade without intermediate finishing . According to the method of the present invention, the end mill does not interfere with the curvature of the recess of the material, and the material can be cut by cutting the material with a large cut.
[0006]
By machining the end mill at a slight angle from the right angle to the blade surface, it is possible to complete the blade surface with good finishing roughness even when machining with a large feed pitch.
In addition, in order to support a raw material with high surplus (removal allowance) that remains unprocessed and highly rigid at at least one end in the longitudinal direction, and to direct the cutting force from the other end side toward the rigid support side, Cutting can be performed with a large cut. In addition, the finished shape can be machined once and the cutting force is not suitable for the blade thickness direction (perpendicular to the blade surface), so there is little deformation of the material and chatter vibration does not occur. Surface roughness can be obtained, for example, the dimensional accuracy of the leading and trailing edges of the blade surface can be ensured, and rounding hand finishing is not necessary.
[0007]
Further, according to the reference example , instead of the end mill, a side cutter that rotates about an axis parallel to the longitudinal direction of the material is used, and the radius of the side cutter is the minimum radius of a thin member such as a wing. Set the material smaller and cut the material. By this method, cutting can be performed with a large cut without controlling the rotation axis of the tool. Accordingly, it is possible to apply an NC machining apparatus with a small number of numerical control axes.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.
[0010]
Figure 1 is a diagram showing an implementation form of the cutting method of the wings of the present invention, FIG. 2 is a sectional view taken along the line A-A of FIG. As shown in FIG. 1, in the method of the present invention, first, a material 4 having a sufficient allowance for a desired thin blade 1 and having a high rigidity is prepared. The rigidity of the material is set so that the deformation due to the cutting resistance is sufficiently small even if the desired blade 1 is cut by one cutting, at least in the material stage.
[0011]
In implementation form, the processing equipment uses a NC control device 5 axes. That is, a flat bottom end mill 6 is used as a tool, and this is controlled in three axes, x, y, and z, and the inclination θ of the rotation axis is numerically controlled. Further, at least one end in the longitudinal direction of the material 4 (both ends in this example) is supported by the fixture 11 (and the center support tool 12), and the rotation table 13 sets the rotation angle α around the longitudinal axis y of the material 4 by the rotary table 13. Numerical control.
[0012]
The end mill 6 having a flat bottom surface is inclined at an angle of θ (3 to 5 °) with respect to the machining surface so that the bottom surface contacts the machining surface of the desired blade 1 at one point. That is, the radius of the end mill 6, as well as smaller than the minimum radius of the desired blade 1, the processed surface of the bottom to the numerical control of the tilt angle θ so as not to interfere with other than the processing point on the processed surface, bottom blade 1 Is controlled to always have an angle of 3 to 5 °.
[0013]
With the above-described configuration, in the method of the present invention, the rotation angle α, the inclination angle θ, and the position (x, y, z) of the tool are numerically controlled, and the desired blade 1 is removed from the other end in the longitudinal direction of the material 4. The wings are made by cutting the material while turning around the material. A desired blade is processed to a complete shape at once by this one-time cutting .
[0014]
3 is a diagram showing the relationship between the tool and the machining surface in FIG. 1. FIG. 3A is a diagram showing the relationship between the end mill 6 and the machining surface of the blade 1, and FIG. As described above, the machining pitch P is made relatively large (for example, 1 to 5) by numerically controlling the inclination angle θ so that the bottom surface of the end mill 6 is always at an angle of 3 to 5 ° with respect to the machining surface of the blade 1. 2mm), it is possible to reduce the caps that are uncut from the tool as shown in the figure. As a result, a machined surface with good finishing roughness can be obtained even if machining is performed at a relatively large feed pitch. For example, when the tool r on the bottom shoulder of the end mill 6 is about 0.5 to 1.0 mm and the processing pitch P is 1 mm, the average roughness Ra of the processing surface is about 0.8 μm or less, and almost manual finishing is required. A smooth surface was obtained.
[0015]
4A and 4B are diagrams showing a method of cutting a thin member such as a wing according to a reference example , in which FIG. 4A is a side view and FIG. 4B is a cross-sectional view taken along line BB. In this example, a 4-axis NC control device is used as the processing device. That is, a side cutter 7 that rotates about an axis parallel to the longitudinal direction of the material is used as a tool, and this is controlled by three axes x, y, and z (the tilt of the rotation axis is not controlled). Further, the rotation angle α is numerically controlled around the longitudinal axis y of the material 4 supported at at least one end in the longitudinal direction of the material 4. Further, the side cutter 7 sets the radius of the side cutter smaller than the minimum radius of the desired thin member 1 in order to avoid interference with the desired thin member 1. Other methods are the same as the implementation form of FIG.
[0016]
According to the wing cutting method of the present invention described above, the raw material 4 having a large amount of surplus material (removing allowance) is supported at at least one end in the longitudinal direction, and is rigid from the other end side. Since the cutting force is directed in the direction of the support side, cutting can be performed with a large cut. In addition, the finished shape can be processed once, and the cutting force is not directed in the thickness direction of the blade 1 (the direction perpendicular to the blade surface), so there is little deformation of the material, and chatter vibration does not occur. The machined surface roughness can be obtained, and for example, the dimensional accuracy of the leading edge and trailing edge of the blade surface can be ensured, and rounding hand finishing is not necessary.
[0017]
In addition, by using the end mill 6 and, for example, machining by slightly tilting the blade surface from a right angle, it is possible to complete the blade surface with good finishing roughness even when machining with a large feed pitch.
[0018]
In the reference example, the method of using the side cutter 7 can perform cutting with a large cut without controlling the rotation axis of the tool. Accordingly, it is possible to apply an NC machining apparatus with a small number of numerical control axes.
[0019]
In addition, this invention is not limited to embodiment mentioned above, Of course, it can change variously, unless it deviates from the summary of this invention.
[0020]
【The invention's effect】
As described above, the present invention has the following features 1 to 3 .
1. By thinly cutting a thin wing and machining it without intermediate finishing, the occurrence of chatter can be eliminated. At this time, it is processed from the tip to the root while turning around the wing.
2. In order not to generate chatter, it is tilted slightly on the wing surface so that it does not interfere with the curvature of the dent on the ventral side and is subjected to cutting resistance in the direction of the base of the material.
3. Even if the pitch is increased, the remaining cusp of the end mill is eliminated and hand finishing is reduced.
4). It is possible to reduce the rounding radius of the end mill , to reduce the cutting resistance that generates a burr perpendicular to the machining surface (blade surface) of the blade , and to reduce the cusp, thereby improving the finishing degree.
[0021]
Therefore, the cutting method of the wings of the present invention can be very thin blade thickness, without repeating processing until finishing operation from roughing, and without using a special jig, cutting, And so on.
[Brief description of the drawings]
1 is a diagram showing an implementation form of the cutting method of the wings of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA in FIG.
FIG. 3 is a relationship diagram between a tool and a machining surface in FIG. 1;
4 is a diagram showing a reference example of a method of cutting a thin walled member.
FIG. 5 is a schematic diagram showing a conventional blade cutting method.
[Explanation of symbols]
1 blade (thin member) , 2 mounting jig, 3 ball end mill, 4 material, 6 end mill, 7 side cutter, 8 cusp, 11 mounting tool, 12 center support tool, 13 rotary table

Claims (3)

Prepare a material with sufficient allowance for turbine or compressor blades , prepare an end mill that does not interfere with the curvature of the dent of the blade , and the bottom surface of the end mill is flat,
One end of the material in the longitudinal direction is supported by a fixture, and the end mill has a portion that becomes the antinode of the wing and a portion of the antinode in a state in which the rotation axis of the end mill is oriented perpendicular to the processing surface of the wing. Cutting the material once from the other end in the longitudinal direction to the one end in the longitudinal direction while rotating around the material so as to alternately pass through the wing portions on the opposite side Thus , the blade cutting method is characterized in that the material is made into a complete shape of the blade without intermediate finishing . 2. The state according to claim 1, wherein the rotation axis of the end mill is oriented substantially perpendicular to the machining surface of the blade so that a cutting force is hardly directed in the thickness direction of the blade. The wing cutting method described. 3. The blade cutting method according to claim 1, wherein the rotation angle of the material is controlled numerically about an axis from one end in the longitudinal direction toward the other end in the longitudinal direction .

Images