JP2007264749A - Method and apparatus for machining rotating element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for machining a rotating element to surely machine the center of rotation of a workpiece to be machined while being rotated. <P>SOLUTION: The method for machining a rotating element has a step for calculating the center of rotation of the workpiece on the basis of the three-dimensional shape of the workpiece and a step for rotatably holding one end of the workpiece while moving the other end of the workpiece to align the workpiece with the center of rotation calculated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rotating body processing method and a rotating body processing apparatus.

  For example, in order to rotate an object having a complicated shape such as a crankshaft, it is necessary to first determine the rotation center of a workpiece, which is an object to be processed, and then perform positioning. If rotational processing is performed without obtaining the center of rotation, additional processing for balancing the object after finishing is required.

Therefore, in the past, in order to eliminate such additional processing, in the case of a workpiece, for example, a crankshaft after forging, a representative part of the workpiece is measured and measured in advance to a conversion formula for predicting the center of rotation. The center of rotation was obtained by entering a value (see, for example, Patent Document 1).
JP 09-174382 A

  However, in the conventional method, although a center position for rotational machining can be obtained, a method for accurately positioning a workpiece to be machined at the center position is not considered.

  Accordingly, an object of the present invention is to provide a rotary machining apparatus capable of positioning the rotation center of a workpiece to be rotary machined so as to achieve results.

  In order to achieve the above object, the present invention includes a step of calculating a rotation center of the workpiece from a three-dimensional shape of the workpiece, holding one end of the workpiece rotatably, and moving the other end of the workpiece. And a step of aligning the workpiece with the calculated center of rotation.

  In order to achieve the above object, the present invention includes a workpiece support means for supporting both ends of a workpiece, and a rotation center calculation means for calculating a rotation center of the workpiece from a three-dimensional shape of the workpiece, and the workpiece support The means is free to move so as to pivot about the fulcrum, with the first chuck pivotally supported about one end of the workpiece and the other end of the workpiece. The second chuck is moved, and the second chuck is moved to align the workpiece so as to be the rotation center calculated by the rotation center calculation means. It is a body processing device.

  According to the present invention, by comparing the shape obtained by measuring the three-dimensional shape with the virtually created shape, the rotation center at the time of rotational processing is obtained, and the workpiece is obtained at the obtained rotation center. Therefore, it is possible to perform machining with a balanced rotation of the workpiece.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the present embodiment, first, a method for calculating the rotation center of the rotating body will be described, and then the rotating body processing apparatus will be described.

  FIG. 1 is a block diagram for explaining a system for calculating the rotation center of a rotating body and processing the rotating body by applying the present invention.

  This system predicts the center of rotation from a three-dimensional measuring machine 1 for three-dimensionally measuring a rough material (a workpiece before processing) as a workpiece, and from the measured three-dimensional shape and the finished shape of the workpiece after finishing. It consists of a computer 2 and a rotating body processing apparatus 3 that performs processing while fixing a workpiece. Here, the computer 2 serves as a rotation center calculation means, and the rotation center that is the rotating body machining center is calculated by the computer 2 executing a program created based on a procedure described later.

  The three-dimensional measuring machine 1 can use the three-dimensional measuring machine 1 marketed, and is not specifically limited. For example, a CT scanner, a laser-type or ultrasonic-type non-contact digitizer that can measure a workpiece at regular intervals is preferable. For example, in the case of a crankshaft having a length of about 50 cm and a maximum diameter of about 10 cm, the measurement interval is preferably about 0.1 mm. Of course, in the case of a larger workpiece, the measurement interval may be appropriately increased.

  The computer 2 serves as a rotation center calculation means, and obtains the rotation center of the workpiece by a processing procedure described later. As such a computer, for example, a personal computer or a workstation can be used.

  The rotary body processing apparatus 3 is an application of the present invention, and holds a workpiece (here, a crankshaft after forging) 100 on the front F side and the rear R side, which are both ends in the axial direction, and holds each side. It is a machine tool that can move left and right (X direction) and up and down (Y direction) and rotates the workpiece 100 while it is pivotally supported (see FIG. 3).

  For this purpose, the rotating body processing apparatus 3 includes a front side chuck 101 (first chuck) and a rear side chuck 102 (second chuck) on the base 103 (details will be described later).

  FIG. 2 is a flowchart showing a processing procedure for obtaining the rotation center by the computer 2.

  Here, a crankshaft after forging will be described as an example of the workpiece. FIG. 3 is a perspective view showing a crankshaft that is the workpiece 100.

  As shown in the figure, the crankshaft is provided with counterweights and balance weights in various directions, so it is not possible to know where the balanced center of rotation is. Moreover, since the rough material (work before processing) after forging has a flesh that cannot be formed by forging alone, such a portion is finished by rotating with the center of rotation positioned. The arrow A shown in the figure is the position that is the center of rotation. The center of rotation is obtained as a balanced position as a finished rotating body after processing by the method of the present embodiment.

  Hereinafter, a processing procedure for obtaining the rotation center will be described.

  First, a workpiece is fixed to the rotating body machining apparatus 3 (S0). For fixing the work, the front side and the rear side of the crankshaft are fixed to the rotating body processing device 3 at a place that seems to be the center of rotation for the time being. At the time of fixing, the rotation center (Z-axis direction) is set as the origin (0 point) on the XY coordinates on each of the front F side and the rear R side shown in FIG.

  Next, the entire workpiece is three-dimensionally measured at a predetermined interval (S1). The measurement result is taken into the computer 2, further impositioned, and stored in the storage means of the computer 2 (S2). Here, the storage means is, for example, a hard disk in the computer 2.

  Thereafter, the cutting trajectory of the cutting tool is simulated by the computer 2 to obtain a virtual finished shape after the rotational processing (S3). The cutting tool processes the workpiece and finishes it into a final shape by rotating the workpiece (here, the workpiece of the crankshaft) and adjusting the cutting depth in accordance with the rotation. The cutting depth is determined in advance from the design shape of the workpiece with respect to the rotation center of the workpiece. Therefore, the finished shape can be understood by simulating the trajectory of the cutting tool.

  The reason why the finished shape is created by simulating the trajectory of the cutting tool is that a shape similar to the shape after the actual cutting is virtually obtained as accuracy. Of course, if a finished shape with the same degree of accuracy can be obtained, a finished shape to be compared may be created from a design drawing or the like.

  Subsequently, the computer 2 subtracts the shape of the three-dimensional measurement result from the simulation completed shape (S4). By subtracting this shape, an extra portion of the three-dimensional shape obtained by measurement is removed from the finished shape by simulation, and the shape after being actually processed is predicted (the shape obtained thereby) Is referred to as a predicted finished shape).

  After that, the center of rotation as the rotating body is obtained from the predicted finished shape from which the excess portion has been removed.

  In order to obtain the center of rotation, first, a balance calculation with respect to the central axis of rotation is executed (S5).

  The balance calculation may be performed by extracting only the portion that affects the overall balance.

  FIG. 4 is a diagram showing a model shape in which a portion necessary for balance calculation in the crankshaft is extracted.

  In the case of a crankshaft, a portion that is processed into a cylindrical shape at a fixed distance from the rotation center is omitted because it does not affect the balance calculation. Therefore, as shown in the figure, it is only necessary to have a shape in which only portions such as the counterweight and balance weight of the crankshaft are extracted.

  In the balance calculation, the positions of the center of gravity of a plurality of counterweights and balance weights of the crankshaft are distributed to the front and rear balance positions as moments.

  FIG. 5 is an explanatory diagram for explaining a method of distributing the moment of the workpiece to the front and rear balance positions.

  As shown in the drawing, the center of gravity position of the counterweight or balance weight is represented by a vector W1 from the center position C (line segment C in the figure), and when the length WR1 is taken, the distribution amount is WR1 × a1 / on the front F side. L, rear R side becomes WR1 × b1 / L. Actually, as will be described later, since XY coordinates are used when determining the center of rotation, both WRx and WRy are obtained from the coordinate values in the X and Y directions on the front F side and the rear R side, respectively. The front F side calculates WR1x × a / L, WR1y × a / L, and the rear R side calculates WR1x × b / L and WR1y × b / L.

  Note that the same applies to W2, and FIG. 6 shows two of W1 and W2. Actually, however, the moments are distributed according to the number of counter weights and balance weights.

  The XY coordinate positions where a plurality of moments are distributed in this way are set as the center positions X and Y of the target eye.

  Then, the rotation center is calculated so as to be the center position X, Y of the target eye obtained by the balance calculation (S6).

  FIG. 6 is an explanatory diagram for explaining a method of calculating the rotation center.

  As for the center of rotation, the center of weight is calculated by looking at the model shape obtained by extracting the part necessary for the previous balance calculation from the direction of skewing as shown in FIG. Let this value be x, y. In the drawing, there are two center positions because the center viewed from the front side and the center viewed from the rear side are overlapped in the same plane. That is, in FIG. 4, if the center of the axis is the Z-axis direction, the center position of the crankshaft is different between the front side and the rear side in the XY plane. In the figure, the front center position is indicated as Fc, and the rear center position is indicated as Rc. Each line is an outline of each part extracted in FIG.

  Then, the obtained x and y positions are brought closer to the previously obtained X and Y positions. Do this for both the front and rear sides. Then, since the position of the center position C when X and Y are obtained differs, the distribution with the moment is performed again, and the values of X and Y are recalculated. Then, the center position C is brought closer to the recalculated X and Y again. That is, as calculation, X and Y are recalculated repeatedly until the value of the following formula (1) becomes the smallest.

((X−x) ² + (Y−y) ² ) ^(1/2) (1)
However, in actuality, calculation until the value of the expression (1) becomes the smallest may be repeated infinitely, so the values of the center positions x and y are gradually changed by an experimental design method or the like. Then, if it finally becomes less than a predetermined threshold value, the values of x and y at that time may be determined as the rotation center. The threshold value at this time is obtained, for example, by determining the moment distance WR and the center position C of the product (which is the center of the position where the shaft hole is opened in the actual product) by ( 1) Take the value of the equation and use that value as the threshold value.

  And if the value of (1) Formula becomes below a threshold value (S7: Yes), it will be rotated by the center position which finally calculated | required the shape obtained by three-dimensional measurement, and it overlaps with the cutting locus of a cutting tool. In addition, it is determined whether or not cutting is possible (S8), and the process ends. In this determination, if there is a portion where the shape obtained by the three-dimensional measurement is smaller than the shape of the cutting locus of the cutting tool, it is determined that cutting is impossible. If cutting becomes impossible, a message to that effect is displayed on the computer display (S10).

  If there is no abnormality in S8, the positions of the front side and the rear side of the cutting machine 3 fixing the workpiece are finally obtained x and y positions so that the obtained center position is obtained. (S9). As a result, the finished shape of the crankshaft after actual processing is balanced.

  FIG. 7 is a drawing showing details of the chuck portion of the rotating body machining apparatus 3, wherein (a) shows the front side chuck 101 and (b) shows the rear side chuck 102.

  FIG. 8 is an explanatory diagram for explaining a state in which the workpiece is chucked.

  One of the chuck portions of the rotating body machining apparatus 3 is supported at two points, and the other is supported at four points. In the present embodiment, the front side chuck 101 is supported at two points, and the rear side chuck 102 is supported at four points. Of course, the reverse may be possible.

  The rear chuck 102 is movable in the X-axis direction and the Y-axis direction while supporting the workpiece at four points. On the other hand, it is not necessary for the front chuck 101 to move with the workpiece pivotally supported.

  As a means for moving the rear chuck 102, although not shown, for example, a ball screw mechanism for moving the entire rear chuck 102 in the X-axis direction and a ball screw mechanism for moving the Y-axis direction may be provided.

  The chuck portion 111 of the front side chuck 101 has an inverted wedge shape, and when the rear side is moved in the X-axis and / or Y-axis direction instead of the chuck portion 111 being in close contact with the workpiece, The front side center position Fc (see FIG. 8) can be turned as a fulcrum. For this reason, the front side chuck 101 is supported at two points so as to be easily rotated.

  On the other hand, the chuck portion 121 of the rear chuck 102 is supported at four points so that the workpiece can be held and rotated without dropping the workpiece.

  As a result, as shown in FIG. 8, the workpiece 100 is rotatable in the directions of arrows A and B with the center position Fc on the front side as a fulcrum by the movement of the rear side chuck 102. Further, the movement of the rear side chuck 102 makes it possible to rotate the entire workpiece centering on the figure C. Note that the rotation range of the entire work centered on the figure C is defined by the operation range of the rear side chuck 102.

  Using such a rotating body machining apparatus 3, the workpiece is aligned at the rotation centers x and y finally obtained as described above.

  In this alignment, first, the coordinate system is aligned so that the center position Fc of the front side chuck 101 coincides with the origin of the front side coordinate system used for calculating the center position. The coordinate system is also moved on the rear side by the amount of alignment.

  For example, it is assumed that the obtained center position on the front side is x, y = 1, 2 in the coordinate system in the computer. Then, in order to match the coordinate system on the front side of the rotating body processing apparatus 3, the coordinate values of the center position obtained on the front side may be set to x−1 and y−2. Thus, the obtained center position on the front side coincides with the position of the origin Fc of the coordinate system on the front side of the rotating body processing apparatus 3. In order to match this, the center positions x and y obtained on the rear side may be set to x−1 and y−2 (of course, numerical values such as “1, 2” shown here are However, the present invention is not limited to the coordinate values used in the computer 2 and the rotary body processing apparatus 3 in actual operation. ).

  In this way, the front side and rear side coordinate systems in the computer 2 can be matched with the front side and rear side coordinate systems in the rotary body machining apparatus 3. As a result of this coordinate alignment, the rotation center on the front side coincides with the previously calculated rotation center.

  Therefore, the rear side chuck 102 of the rotating body processing apparatus 3 is moved using the rear side coordinate values after the coordinate alignment. As a result, the rear side is also aligned with the position of the center of rotation obtained as described above.

  Such coordinate conversion and position adjustment are convenient when the ball screw mechanism for moving the rear chuck 102 is operated under the control of the computer 2 to automatically perform the alignment. Of course, it is also possible to read the rotation center coordinates on the front side and the rear side indicated by the computer and move the rear side chuck 102 of the rotary body processing device 3 by sliding to perform alignment.

  After aligning the center of rotation as described above, the center hole is drilled in the Z-axis direction shown in FIG. Drilling of the center position can be performed. The center hole thus formed becomes a balanced center position in the finished shape after cutting with the workpiece 100 as a rotating body.

  Further, the cutting may be performed as it is in the rotating body processing apparatus 3 as a rotating body, or after the center drilling, the center hole is further supported by another machine tool or the like to perform additional cutting. However, the finished shape is finished in a balanced shape as a rotating body.

  According to the present embodiment described above, the center of rotation at the time of rotational processing can be obtained by comparing the shape obtained by measuring the three-dimensional shape with the shape after cutting virtually created in the computer. The center of rotation can be obtained with high accuracy, and the workpiece can be used without re-adjusting the balance even after machining the workpiece. It becomes possible.

  In addition, the rotating body machining apparatus according to the present embodiment, in a state in which one end of the workpiece is pivotally supported, first adjusts the coordinate system of the rotation center position obtained after stopping the rotation on this side, and performs other operations accordingly. Since the end side coordinates are aligned and the other end side is aligned, one chuck (in this embodiment, the front side chuck) can pivotally support one end of the workpiece in a rotatable manner. Since it suffices, the device configuration is simple.

  The present invention is suitable for center positioning when finishing various workpieces such as forged products and pressed products.

It is a block diagram for demonstrating the system for calculating the rotary body process center to which this invention is applied. It is a flowchart which shows the process sequence for calculating | requiring a rotation center with this computer by applying this invention. It is a perspective view which shows a crankshaft. It is drawing which shows the model shape which extracted the part required for the balance calculation in a crankshaft. It is explanatory drawing for demonstrating the method to distribute the moment of a workpiece | work to the front-back balance position. It is explanatory drawing explaining the calculation method of a rotation center. It is drawing which shows the detail of the chuck | zipper part of a rotary body processing apparatus, (a) shows the front side chuck | zipper 101, (b) shows the rear side chuck | zipper 102. FIG. It is explanatory drawing for demonstrating the state which chuck | sucked the workpiece | work.

Explanation of symbols

1 ... 3D measuring machine,
2 ... Computer,
3 ... Rotating body processing apparatus.

Claims (6)

Calculating the rotation center of the workpiece from the three-dimensional shape of the workpiece;
One end of the work is held rotatably, and the other end of the work is moved to align the work with the calculated rotation center,
A rotating body machining method characterized by comprising: Calculating the center of rotation of the workpiece,
Capturing the result of measuring the three-dimensional shape of the workpiece and storing it in a storage means of a computer;
A step of creating a finished shape after rotational processing of the workpiece by simulation;
Removing an extra portion from the stored three-dimensional shape of the workpiece with respect to a finished shape by the simulation;
Calculating the center of rotation from the shape obtained by removing the excess part;
The rotating body processing method according to claim 1, comprising: The step of calculating the rotation center includes
(A) distributing a moment as a rotating body having a shape excluding the extra portion according to a distance from the rotation center;
(B) bringing the center of rotation closer to the center of gravity of the distributed moment,
3. The step (a) and the step (b) are repeatedly executed until the relationship between the center of gravity position and the rotation center close to the center of gravity is equal to or less than a predetermined threshold value. The rotating body processing method as described. Workpiece support means for supporting both ends of the workpiece;
Rotation center calculating means for calculating the rotation center of the workpiece from the three-dimensional shape of the workpiece,
The workpiece support means includes
A first chuck that pivotally supports an end of the workpiece as a fulcrum;
A second chuck that pivots on the other end of the workpiece and is movable so as to rotate the workpiece about the fulcrum, and moves the second chuck, A rotating body machining apparatus, wherein the workpiece is aligned so as to be the rotation center calculated by a rotation center calculation means. The rotation center calculating means includes
The finished shape of the workpiece after the rotational machining was simulated, and the extra portion was removed from the three-dimensional shape of the workpiece obtained by the three-dimensional shape measuring means with respect to the finished shape obtained by the simulation, and the extra portion was removed. The rotating body processing apparatus according to claim 4, wherein the center of rotation is calculated from the shape. The rotation center calculating means includes
Distributing the moment as a rotating body having a shape excluding the excess portion according to the distance from the rotation center, and calculating the rotation center by bringing the rotation center closer to the center of gravity of the allocated moment. 6. The rotating body processing apparatus according to claim 5, wherein the rotation body processing apparatus is repeatedly executed until a relationship between the position of the center of gravity and the rotation center approached is equal to or less than a predetermined threshold value.

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