JP2018179044A - Crankshaft shape measurement implement and crankshaft shape measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a center hole decision device of a raw-material crankshaft which can exactly regenerate an actual shape of the raw-material crankshaft.SOLUTION: A center hole decision device 20 comprises an elongation rate calculation part 20b, a correction part 20c and a center hole decision part 20d. The elongation rate calculation part 20b calculates an elongation rate U for elongating and contracting a plurality of divided regions DR which are set around a center P2 of a design shape of a counter weight CW so as to match an actual shape of the counter weight CW in a radial direction. The correction part 20c acquires correction coordinates (x'xU, y'xU, z) of a center of gravity Q2 and a correction volume V×Uof each divided region DR by correcting coordinates (x', y', z) of the center of gravity Q2 and a volume V of each divided region DR on the basis of the elongation rate U. The center hole decision part 20d decides a center hole of a raw-material crankshaft 1 on the basis of correction coordinates (x'xU, y'xU, z) and the correction volume V×U.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a crankshaft shape measuring machine and a crankshaft shape measuring method.

  Since a crankshaft is used by being incorporated into an engine, there is a problem such as occurrence of vibration at the time of engine rotation if there is a rotation imbalance amount. Therefore, it is necessary to reduce the amount of rotational imbalance of the crankshaft.

  In order to reduce the amount of rotational imbalance of the crankshaft, the actual shape of the material crankshaft before processing is accurately grasped, and the inertial spindle that achieves the optimum balance in the finished product state is calculated, and the material crank on the calculated inertial spindle It is important to form the center hole which becomes the processing standard of a shaft.

  Here, Patent Document 1 proposes a method for interpolating an error due to a deviation between an upper mold and a lower mold used for molding of a material crankshaft for the purpose of accurately reproducing the actual shape of the material crankshaft. There is.

Unexamined-Japanese-Patent No. 2010-031987

  However, in the method of Patent Document 1, interpolation calculation of the error due to the difference between the upper die and the lower die is not easy, and the error due to factors other than the difference between the upper die and the lower die can not be suppressed. There is also a limit to reducing the amount of shaft rotation imbalance.

  The present invention is made in view of the above-mentioned situation, and an object of the present invention is to provide a center hole deciding device of a material crankshaft which can reproduce the actual shape of the material crankshaft accurately.

  A center hole determination device according to the present invention is for determining a center hole of a material crankshaft having at least one counterweight, and includes an expansion / contraction ratio calculation unit, a correction unit, and a center hole determination unit. . The expansion / contraction ratio calculation unit calculates an expansion / contraction ratio for expanding / contracting each of the plurality of divided regions set around the design shape of the counterweight in the radial direction so as to match the actual shape of the counterweight. The correction unit acquires the correction coordinates of the center of gravity of each of the plurality of divided areas and the correction mass by correcting the coordinates and mass of the center of gravity of each of the plurality of divided areas based on the expansion ratio. The center hole determination unit determines the center hole of the material crankshaft based on the correction coordinates and the correction mass.

  According to the present invention, it is possible to provide an apparatus crankshaft center hole determining apparatus capable of accurately reproducing the actual shape of the material crankshaft.

An appearance perspective view of an example of a material crankshaft. The block diagram of the processing system of a raw material crankshaft. The figure which shows the design shape and real shape of a counterweight. The figure for demonstrating the best fit to the real shape of the design shape of counterweight. The figure for demonstrating expansion-contraction of each division area of a counterweight. The figure which shows the division area of a counter weight.

[Material Crankshaft 1]
FIG. 1 is an example of a material crankshaft 1 and shows here a material crankshaft for an in-line four cylinder engine. The material crankshaft 1 is formed, for example, by forging or casting.

  The material crankshaft 1 has four main journals J (J1 to J5), four pin journals P (P1 to P4), and eight counterweights CW (CW1 to CW8). In the material crankshaft 1, in the Z-axis direction, main journal J1, counter weight CW1, pin journal P1, counter weight CW2, main journal J2, counter weight CW3, pin journal P2, counter weight CW4, main journal J3, counter weight The CW5, the pin journal P3, the counter weight CW6, the main journal J4, the counter weight CW7, the pin journal P4, the counter weight CW8, and the main journal J5 are arranged in this order.

[Crankshaft processing system 100]
Next, a crankshaft processing system 100 according to the embodiment will be described with reference to FIG. 2 (a) is a hardware configuration diagram of the crankshaft processing system 100, and FIG. 2 (b) is a functional configuration diagram of the center hole determination device 20. As shown in FIG.

  The crankshaft processing system 100 determines a center hole processing machine 10 as an example of processing means for processing a center hole on both end surfaces of the material crankshaft 1 and positions of center holes to be processed on both end surfaces of the material crankshaft 1 And a crankshaft processing machine 30 for performing predetermined processing on a material crankshaft on which the center hole is formed.

  The center hole processing machine 10 is provided with a shape measuring machine 11 as an example of measuring means for measuring the shape of the material crankshaft.

  The shape measuring machine 11 has, for example, a non-contact displacement sensor such as a laser displacement sensor, an infrared displacement sensor, an LED displacement sensor, or a contact displacement sensor such as an operation transformer, and based on the measurement value from the displacement sensor The shape of the material crankshaft 1 is measured. In the present embodiment, the shape measuring machine 11 measures only the outer shape of each counterweight CW of the material crankshaft 1. This is because each main journal J and each pin journal P hardly affect the rotational unbalance amount of the crankshaft, so the center hole determining device 20 described later is based on the outer shape of each counter weight CW. The reason is that

  The shape measuring machine 11 may be a three-dimensional digitizer (image scanner) that generates the entire shape of the material crankshaft as three-dimensional shape data by measuring the measurement object from a plurality of different positions.

  The center hole determination device 20 is a processing device for determining the position of the center hole to be machined on both end surfaces of the material crankshaft 1. The center hole determination device 20 includes a central processing unit (CPU) 21, a read only memory (ROM) 22, and a random access memory (RAM) 23.

  The ROM 22 stores various programs to be executed by the CPU 21 and various information. In the present embodiment, the ROM 22 stores a program of processing for determining the position of the center hole of the material crankshaft 1 described later. The ROM 22 also stores design shape data indicating the design shape of each of the eight counterweights CW of the material crankshaft 1. The ROM 22 may store the processing content of the material crankshaft 1 in the crankshaft processing machine 30.

  The RAM 23 is used as an area for storing programs and data, or as a work area for storing data used for processing by the CPU 21.

  As the CPU 21 reads out the program stored in the ROM 22 to the RAM 23 and executes the processing, as shown in FIG. 2B, the center hole determination device 20 acquires the real shape data acquisition unit 20a and the expansion ratio calculation unit It functions as 20b, the correction part 20c, and the center hole determination means 20d.

[Function of Center Hole Determination Device 20]
Hereinafter, the function of the center hole determination device 20 will be described.

<Real shape data acquisition unit 20a>
The actual shape data acquisition unit 20 a acquires, from the shape measuring machine 11, actual shape data indicating the shapes of the eight counterweights CW of the material crankshaft 1.

  The shape measuring machine 11 measures the shape of each counter weight CW. Specifically, the shape measuring machine 11 measures the outer peripheral contour position of each of the counterweights CW, as shown by ● in FIG. Thereby, the shape measuring machine 11 generates actual shape data indicating a two-dimensional actual shape of each counter weight CW. Note that FIG. 3 schematically shows the measurement positions, and in fact, the measurement may be performed at more positions than those shown in FIG.

  As a method of measuring the shape of each counterweight CW, for example, a method of measuring while rotating the material crankshaft 1 by fixing a displacement gauge, fixing the material crankshaft 1 and surrounding the displacement gauge There is a method of measuring while rotating, or a method of measuring while linearly moving a displacement meter arranged so as to sandwich the material crankshaft 1 from above and below, but it is not limited thereto.

<Stretch ratio calculation unit 20b>
The expansion / contraction ratio calculation unit 20 b acquires, from the ROM 22, design shape data indicating a design shape of each of the counterweights CW of the material crankshaft 1. The expansion / contraction ratio calculation unit 20b acquires actual shape data indicating the actual shape of each counterweight CW from the actual shape data acquisition unit 20a.

  As shown in FIG. 3, the position and angle of the actual shape are offset with respect to the position and angle of the design shape. In FIG. 3, the design shape is shown as a solid line, but the actual design shape is shown by a number of polar coordinates. The number of polar coordinates is not particularly limited. For example, 360 polar coordinates can be set at equal angles (1 degree) around the center P1 of the counter weight CW.

  Here, as shown in FIG. 3, in the design shape, a plurality of divided areas DR are set around the center P1 of the counter weight CW. Each divided area is substantially fan-shaped. The number of divided regions DR is not particularly limited, but in FIG. 3, 32 equal angles (11.25 degrees) are set around the center P1 of the counter weight CW. The center P1 of the counterweight CW is the geometric center of the counterweight CW in plan view. The design shape data includes the coordinates (x, y, z) of the center of gravity Q1 (only one center of gravity Q1 is shown in FIG. 3) of each divided area DR and the volume V of each divided area R. The expansion / contraction rate calculation unit 20b associates and stores the coordinates (x, y, z) of the center of gravity Q1 and the volume V for all the divided areas DR. The z-axis is the axial direction of the material crankshaft 1, the x-axis is the direction perpendicular to the z-axis, and the y-axis is the direction perpendicular to the z-axis and the x-axis.

  Next, as shown in FIG. 4, by using the best fit method, the expansion / contraction ratio calculation unit 20b moves and / or rotates the design shape so as to fit the real shape, thereby making an error between the design shape and the real shape. Find the position where the sum of squares of is the smallest. Then, the expansion / contraction ratio calculation unit 20b compares the center P1 of the counterweight CW before the best fit with the center P2 of the counterweight CW after the best fit to determine the position displacement m1 in the x-axis direction and the position in the y-axis direction. The displacement m2 and the angular displacement m3 around the z axis are calculated.

  Next, as shown in FIG. 4, the expansion / contraction ratio calculation unit 20b uses the position displacement m1, the position displacement m2, and the angular displacement m3 to calculate the coordinates (x ′, y of the center of gravity Q2 of each divided region DR after best fit. ', Ask for z). The scaling factor calculation unit 20b associates and stores the coordinates (x ', y', z) of the center of gravity Q2 of each divided region DR after the best fit and the volume V. The z-coordinate of the center of gravity Q2 of each divided area DR after the best fit is the same as the z-coordinate of the center of gravity Q1 of each divided area DR before the best fit. Further, the volume V of each divided region DR after the best fit is the same as the volume V of each divided region DR before the best fit.

  Although only one divided region DR in the design shape after the best fit is shown in FIG. 4 in order to show the positional relationship between the gravity centers Q1 and Q2, FIG. 3 also shows the design shape after the best fit. As shown, 32 divided areas DR are set.

  Next, as shown in FIGS. 5A and 5B, the expansion / contraction ratio calculation unit 20b compares the divided region DR after the best fit with the actual shape, and determines the center P2 of the counterweight CW after the best fit. An error value a between the two in the central radial direction is determined. Then, as shown in FIG. 5C, the expansion / contraction ratio calculation unit 20b obtains the sum T (= S + a) of the total length S of the divided region DR in the radial direction and the error value a, and further calculates the sum T The scaling factor U (= T / S) is determined by dividing by the total length S. As described later, the expansion and contraction ratio U is used to expand and contract each divided region DR in the radial direction so as to match the actual shape of the counterweight CW. In the example shown in FIGS. 5A to 5C, since the actual shape plot is located on the radially outer side of the divided region DR, the expansion ratio U is larger than 1, but the actual shape plot is the divided region The expansion ratio U is smaller than 1 when positioned radially inward of the DR.

<Correction Unit 20c>
The correction unit 20c corrects the coordinates (x ′, y ′, z) of the center of gravity Q2 of each divided area DR after the best fit based on the expansion ratio U. Specifically, the correction unit 20c obtains corrected coordinates (x ′ × U, y ′ × U, z) of the center of gravity Q2 of each divided region DR after expansion and contraction. The z-coordinate of the center of gravity Q2 after expansion and contraction is the same as the z-coordinate of the center of gravity Q2 before expansion and contraction.

In addition, the correction unit 20c corrects the volume V of each divided region DR after the best fit based on the expansion ratio U. Specifically, the correction unit 20c obtains a correction volume V × U ² of each divided region DR after expansion and contraction. In the present invention, correcting the volume V of each divided region DR is equivalent to correcting the mass (the product of the volume V and the material density) of each divided region DR.

Then, the correction unit 20c obtains the correction mass M (= V × U ² × α) of each divided region DR by multiplying the correction volume V × U ² by the material density α of the counter weight CW.

  As described above, the size of the divided area DR is expanded or contracted (expanded in FIGS. 5A to 5C) based on the expansion ratio U, whereby the divided area DR is entirely equalized to the actual shape plot position. It can be done. This means that the design shape of the counterweight CW is matched to the actual shape for each divided region DR. Therefore, the actual shape of the counterweight CW can be easily and accurately reproduced.

  The correction unit 20 c obtains 32 sets of correction coordinates (x ′ × U, y ′ × U, z) and a correction mass M for each counter weight CW. Therefore, the combination of the correction coordinates (x ′ × U, y ′ × U, z) and the correction mass M is 32 × 8 = 256 sets per one material crankshaft 1 (32 sets for every 8 counter weights CW) ).

<Center hole determination unit 20d>
As shown in FIG. 6, the center hole determining unit 20 d is configured to correct 256 corrected coordinates (x ′ × U, y ′ × U, z) related to all divided areas DR of all the counter weights CW with the corrected mass M. Assuming that it is a mass point, an inertial main axis of 256 mass points is determined by solving a three-dimensional linear equation under the condition that the product of inertia around the inertial main axis is 0 (zero). Then, the center hole determining unit 20d obtains the center hole position by substituting the z-axis coordinates of both axial end surface positions of the material crankshaft in the obtained x and y formulas of the inertial main axis.

  The center hole position thus determined is sent to the center hole processing machine 10, and the center hole is formed at both end surface positions of the material crankshaft 1. Thereafter, in the crankshaft processing machine 30, processing of the journal portion is mainly performed on the material crankshaft 1 in which the center hole is formed.

[Other embodiments]
(1) In the above embodiment, 32 division areas DR are set in the design shape of each counter weight CW, but the number of division areas DR can be set appropriately, and the number of division areas DR is It may be different for each counter weight CW.

  (2) In the above embodiment, the division areas DR are set at equal angles in the design shape of each counterweight CW, but may not be set at equal angles.

  (3) In the above-mentioned embodiment, although the case where material crankshaft 1 for in-line four-cylinder engine was used was explained, it is not restricted to this. The material crankshaft 1 may have at least one counterweight CW.

  (4) In the above embodiment, when determining the center hole position, the inertial principal axis is determined, but the present invention is not limited to this processing.

1 Material Crankshaft 20a Actual Shape Data Acquisition Unit 20b Expansion Ratio Calculation Unit 20c Correction Unit 20d Center Hole Determination Means CW Counterweight P1 Center Weight of Counter Weight Before Best Fit P2 Center of Gravity of Counter Weight After Best Fit DR Division Area Q1 Best Fit Center of gravity of previous divided area Q2 Center of gravity U of divided area after best fit

Next, as shown in FIG. 4, by using the best fit method, the expansion / contraction ratio calculation unit 20b moves and / or rotates the design shape so as to fit the real shape, thereby making an error between the design shape and the real shape. Find the position where the sum of squares of is the smallest. Then, the expansion / contraction ratio calculation unit 20b compares the center P1 of the counterweight CW before the best fit with the center P2 of the counterweight CW after the best fit, and determines the position displacement M1 in the x-axis direction and the position in the y-axis direction. The displacement M2 and the angular displacement M3 around the z-axis are calculated.

Next, as shown in FIG. 4, the expansion / contraction ratio calculation unit 20b uses the position displacement M1 , the position displacement M2 and the angular displacement M3 to set the coordinates (x ', y of the center of gravity Q2 of each divided region DR after best fit. ', Ask for z). The scaling factor calculation unit 20b associates and stores the coordinates (x ′, y ′, z) of the center of gravity Q2 of each divided region DR after the best fit and the volume V. The z-coordinate of the center of gravity Q2 of each divided area DR after the best fit is the same as the z-coordinate of the center of gravity Q1 of each divided area DR before the best fit. Further, the volume V of each divided region DR after the best fit is the same as the volume V of each divided region DR before the best fit.

Central DR divided region Q1 best fit of 1 material crankshaft 20a actual shape data acquiring unit 20b stretch ratio calculation unit 20c correcting unit 20d center hole determining section CW counterweight P1 counterweight after the center P2 best fit of the best fit before the counterweight Center of gravity of previous divided area Q2 Center of gravity U of divided area after best fit

Claims (3)

A center hole determining device for determining a center hole of a material crankshaft having at least one counterweight, comprising:
An expansion / contraction ratio calculation unit that calculates an expansion / contraction ratio for expanding / contracting each of a plurality of divided regions set around the design shape of the counterweight in the radial direction so as to match the actual shape of the counterweight;
A correction unit that acquires correction coordinates and a corrected mass of the gravity centers of the plurality of divided regions by correcting the coordinates and mass of the gravity centers of the plurality of divided regions based on the expansion ratio;
A center hole determination unit that determines a center hole of the material crankshaft based on the correction coordinates and the correction mass;
Center hole determination device for material crankshaft comprising: The expansion / contraction ratio calculation unit calculates the expansion / contraction ratio at a position where the real shape and the design shape are closest to each other using a least squares method.
A method of determining a center hole of a material crankshaft according to claim 1. The center hole determination unit determines the center hole on the basis of the principal axis of inertia such that the product of inertia around the center line is zero.
A method of determining a center hole of a material crankshaft according to claim 1 or 2.

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