JPH1062144A - Method and equipment for measuring shape of crankshaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine acceptability by determining defect in the shape of a crankshaft, e.g. underfill, quantitatively in a short time with high accuracy. SOLUTION: Three or more points are selected from a part generating no defect of shape as compared with a reference shape. Same number of points constituting a polygon geometrically identical to a polygon defined by the selected points are then detected from a measured shape. The measured shape is superposed on a reference shape such the polygons are matched each other and the measured shape is compared with the reference shape in order to inspect defect in the shape. According to the method, defect in the shape, e.g. underfill, can be measured automatically in a short time with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape measuring method and apparatus for inspecting a crankshaft used for an automobile engine or the like in a manufacturing process.

[0002]

2. Description of the Related Art A crankshaft used for an automobile engine or the like is manufactured by a forging press or the like. For example, FIG.
As shown in the figure, a four-cylinder crankshaft 101 has a plurality of pins 102 for mounting a connecting rod provided along a rotation center axis so as to be at a predetermined angular position from a rotation reference position, and a counterweight for balancing rotation. 103 and a journal 104.

As shown in FIG. 14, the cross-sectional shape of the journal 104 is a concentric circle centered on the center line of the crankshaft 101, and the cross-sectional shape of the pin 102 is
1 is a circle having a center position apart from the center line, and the cross-sectional shape of the counterweight 103 is substantially fan-shaped.

[0004] Such a crankshaft is subject to material dimensional fluctuation,
The quality of the manufactured crankshaft may fluctuate due to fluctuations in the material temperature and fluctuations in the forging operation. For this reason, in the crankshaft manufacturing line, before the final process, the actual shape of the crankshaft is compared with the reference shape to determine whether or not the crankshaft is acceptable.

As a conventional method of inspecting the shape of a crankshaft, a plate gauge formed so as to conform to a reference shape of a pin and a counterweight is fitted to a pin and a counterweight to be inspected of a product crankshaft, respectively.
The gap between each plate gauge, the pin and the counterweight was measured on a scale, and if the shape error was within an allowable range, the crankshaft was determined to be acceptable.

The above method uses a plate gauge formed so as to conform to the reference shape of the pin and the counterweight, and is carried out by an operator's work. It takes a long time.

As a method of solving the above problem, the outer peripheral shape of each journal provided at both ends of the crankshaft is measured by projecting light from an optical displacement sensor, and based on the outer peripheral shape, the axial center of each journal is measured. Is calculated, and a straight line connecting the centers of the shafts is calculated as the center line of the crankshaft, and the actual values of the pins and counterweights provided on the crankshaft are set so that the light emitting axis of the displacement sensor is orthogonal to the centerline of the crankshaft. The shape is measured, the pin and the counter weight stored in the memory are compared with the reference shape, the center position of the pin and the counter weight and the angular position from the reference position are calculated, and the calculated center position and the angular position are calculated. A method and apparatus for comparing a center position and an angular position based on a reference shape (JP-A-6-265334) have been proposed.

[0008]

In the manufacture of a crankshaft, as shown in FIG. 15, a shape defect called underfill occurs in which a part of a measured shape 112 obtained from a shape measuring device is missing from a reference shape 111. May be. For this reason, in the inspection process, it is necessary to inspect whether a shape defect such as underfill has occurred.

The method and apparatus disclosed in Japanese Patent Application Laid-Open No. 6-265334 calculate the center position and angular position of a pin and a counterweight for the purpose of high-accuracy and short-time automatic inspection of a crankshaft. Inspection of the product shape is performed by comparing the center position and the angle position based on the shape, and there is a problem that it is not possible to make a pass / fail judgment based on a shape defect such as a missing portion of the product shape. Was.

SUMMARY OF THE INVENTION An object of the present invention is to provide a crankshaft shape measuring method and apparatus capable of solving the above-mentioned drawbacks of the prior art and quantifying a shape defect such as a missing portion of a crankshaft with high accuracy and in a short time to determine whether or not the crankshaft is acceptable. It is in.

[0011]

According to a first aspect of the present invention, there is provided a crankshaft shape inspection method, wherein at least three points are selected from at least a portion of the reference shape where no shape defect occurs, and the selected points are selected. Detects the same number of points that make up a polygon that has the same geometric shape as the polygon that is composed of the measured points from the measured measurement shape, and superimposes the reference shape and the measurement shape so that the polygons overlap, The shape defect is inspected by comparing the reference shape and the measured shape. in this way,
If the superimposition process is performed using a polygon of a representative shape capable of expressing the reference shape, the calculation processing speed is significantly reduced, and a high-speed inspection process can be performed.

According to a second aspect of the present invention, there is provided a crankshaft inspecting apparatus for measuring a product shape of a crankshaft, a memory storing reference shape data, and at least Three or more points are selected from a portion where no shape defect occurs, and the same number of points that form a polygon having the same geometric shape as the polygon composed of the selected points are measured by the measuring device. A data processing device that detects from the measured measurement shape, superimposes the reference shape and the measurement shape so that the polygons overlap, compares the reference shape with the measurement shape, and performs pass / fail judgment. The shaft shape inspection can be automatically performed in a short time and with high accuracy. In addition, when installing this device on a production line such as a forging press and performing hot measurement of the crankshaft, changes in shape quality due to fluctuations in operating conditions, etc. are continuously and immediately grasped immediately after stamping. Therefore, it is possible to suppress the occurrence of defective products by taking operational measures at an early stage.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The degree to which the counterweight shape of a manufactured product conforms to the reference shape can be determined by superimposing the measured shape obtained using a non-contact measuring instrument or the like on the reference shape. Shape defects can be quantitatively determined. However, in order to superimpose the measured shape and the reference shape, rotation and translation must be performed by a data processing device, and it takes an enormous amount of time to perform the process for all the measured shape points and the reference shape points. , It is difficult to apply online. Therefore, in the present invention, the superimposition process is performed using a representative shape that can represent the reference shape, and the calculation processing speed is greatly reduced to enable a high-speed inspection process.

The method of measuring the shape of the crankshaft according to the present invention will now be described in detail with reference to the flowchart of FIG. In step S1 of FIG. 8, the shape of the counterweight is measured. The measurement of the counterweight shape is performed using a measuring device such as a two-dimensional laser distance meter, but the obtained counterweight measurement shape is superimposed on the reference shape as it is depending on the method of installing the crankshaft at the time of measurement, etc. Since the measurement point cannot be rotated or translated by the data processing device, a portion that does not match the reference shape is determined as a shape defect portion. In order to determine pass / fail, it is necessary to determine whether the measured shape of the counterweight is within an allowable range with respect to the reference shape, and it is necessary to overlap the measured shape with the reference shape.

In step S2, at least three or more points are selected from the reference shapes stored in advance for a portion where no shape defect such as underfill occurs. In general, sites where shape defects are likely to occur are often limited,
If a shape defect is likely to occur near the tip of the arm, three points other than the tip may be selected. The arm shape has a continuous shape formed by curves and curves or curves and straight lines having different curvatures. For example, as shown in FIG.
It is assumed that a, b, and c are selected as three points representing the reference shape 91 among the reference shapes 91. Among the reference shapes 91 of the counterweight to be measured, the shape geometrically identical to the triangular shape composed of three points a, b, and c is the reference shape 9.
If only one exists between point d and point e of 1, the selected 3
Points a, b, and c can be handled as points constituting a triangular shape representing the counterweight shape of FIG.

In step S3, the above three points a,
Three points forming a triangle having the same geometric relationship as the triangle abc composed of b and c are detected from the measured shape. FIG.
The three points a ′, b ′, and c ′ of the zero measurement shape 92 are detected from the measurement shape points so that any of the following relationships is established. Triangles with the same length on all three sides (ab = a'b ', b
c = b'c 'ca = c'a'). A triangle having the same length on two sides and the same angle between the two sides (eg, ab = a'b ', bc = b'c' ∠a
bc = {a'b'c '). A triangle having the same length on one side and the same angle between both ends (eg, ab = a'b ', ∠abc = ∠a'b'c'
∠cab = ∠c'a'b ').

The three points a ′ detected from the measured shape 92,
b ′ and c ′ are three points a selected from the reference shape 91,
Construct a triangle that is geometrically identical to b and c. In step S4, as shown in FIG. 10, rotation and translation are performed so that a and a ', b and b', and c and c 'match, and the reference shape 91 and the measured shape 92 are overlapped.

In step S5, a point which does not match the reference shape 91 among the superimposed measured shapes 92 in FIG.
By comparing 1 with each other, if it is within a predetermined allowable value, it is determined to be acceptable, and if it exceeds the predetermined allowable value, it is determined to be rejected.

In the above description, three points are selected from the reference shape to form a triangle and a geometrically identical triangle is detected from the measured shapes. It is also possible to select from among the shapes in which no shape defects occur, detect a triangle geometrically identical to the triangle formed from the three points from the reference shape, and compare the measured shape with the reference shape.

When the representative shape of the counterweight shape cannot be represented by one triangle, that is, three points that form the same geometric triangle as the triangle composed of the three points selected from the reference shape are the same. If the counterweight exists in the reference shape of the counterweight in addition to the above three points, or if it is desired to further improve the measurement accuracy, four or more points are selected from portions where the shape defect of the reference shape does not occur. For example, as shown in FIG. 11, four points f, g, h, and i are selected from a portion where no shape defect occurs in the reference shape 91, and a rectangle formed by those points f, g, h, and i is selected. Four points f ′, g ′, h ′ that constitute a geometrically identical square
i ′ is detected from the measured shape 92. In this case, the selected four points f, g, h, i and the four detected points f ′,
The relation between g ′, h ′, and i ′ is a rectangle having four sides of the same length (fg = f′g ′, gh = g′h ′, hi = h′i ′,
if = i'f '). When the four points f, g, h, and i are parallelograms, other than the above conditions, two parallel sides and two
It is only necessary that the lengths of the sides are the same. Further, when the four points are square, the condition may be that the two angles are 90 ° and the length of the side between them is the same. Since the four points f ′, g ′, h ′, and i ′ detected in this way form a quadrangle that is geometrically the same as the four points f, g, h, and i selected from the reference shape 91, As shown in FIG. 11, when the reference shape 91 and the measurement shape 92 are overlapped so that these four points respectively match, it becomes clear that a portion of the measurement shape 92 that does not match the reference shape 91 is a shape defect portion.

Further, when measuring with high accuracy, a polygon composed of five or more points from a portion where no shape defect occurs is selected from the reference shape, and a polygon geometrically identical to the polygon is selected. The constituent points are detected from the measured shape points.
By superimposing the reference shape point and the measurement shape point so that the polygons match, a portion of the measurement shape that does not match the reference shape is determined to be a shape defect portion,
The shape defect of the counterweight can be inspected.

According to the above-mentioned measuring method, a point forming a polygon is selected from a portion where a shape defect does not occur in a reference shape, and a point forming a polygon geometrically identical to the polygon is determined from the measured shape. After detection, the method of superimposing the reference shape and the measured shape so that the polygons match was explained.However, the points that constitute the polygon were selected from the measured shapes at points where no shape defects occurred at the measurement points. , The points that constitute a polygon that is geometrically identical to the polygon are detected from the reference shape, and the reference shape and the measured shape are overlapped so that those polygons match, and the reference shape A portion that does not match with the shape can be measured as a shape defect portion.

Further, in order to improve the measurement accuracy, two or more polygons as described above are selected from a portion where no shape defect occurs in the reference shape. By detecting points that form a polygon that is geometrically the same as two or more selected polygons from the measured shape, and by matching the points that make up those polygons, The measured shapes can be overlapped, and a quantitative evaluation of the shape defect can be performed. For example, when two triangles composed of three points are selected from the reference shape, three points j, k, l, m, n, and o may be selected as shown in FIG. And two triangles j
Points that form a triangle geometrically identical to kl and the triangle mno may be extracted from the measured shape.

In the above description, the determination of the cross-sectional shape of the counterweight has been described. However, the same measurement can be performed in the thickness direction in the vertical direction, and inspection for shape defects such as thickness loss in the thickness direction is also possible. is there. Further, it is needless to say that the method of the present invention can be applied to the inspection of a portion where only a polygon for matching the product shape and the reference shape among the reference shapes other than the counterweight exists within the measurement range.

Generally, the surface roughness of a crankshaft is large,
In particular, when performing shape measurement before performing shot blasting or pickling on the crankshaft, an error is likely to occur when the reference shape and the measured shape are overlapped due to the influence of the oxide scale. In order to eliminate the influence of the surface irregularities of the crankshaft, the shape can be inspected with high accuracy by performing a smoothing process on the measured shape data.

[0026]

【Example】

Embodiment 1 Details of a crankshaft shape measuring apparatus according to the present invention will be described with reference to FIGS. 1 and 2 showing an embodiment. FIG. 1 is a schematic perspective view of a crankshaft shape measuring device according to the present invention, and FIG. 2 is an explanatory diagram in which a reference shape and a measured shape are overlapped.

In FIG. 1, reference numeral 1 denotes a crankshaft shape measuring device, and a pair of V blocks 3, 3 on which a crankshaft 2 is mounted.
And two two-dimensional laser rangefinders for measuring the arm shape of the counterweight, which is installed movably along the bed 4 in the longitudinal direction (X direction) of the crankshaft with the counterweight arm of the crankshaft 2 interposed therebetween. A measuring unit 5, a storage unit 6 in which a reference shape of the crankshaft 2 is previously input and stored, a measurement shape of each cross section of the arm end of the counterweight input from the two shape measuring devices 5, and a storage unit And a data processing device 7 for performing a shape inspection by superimposing the reference shapes of the crankshafts inputted and stored in 6 to determine whether the crankshaft is acceptable or not. Reference numeral 8 denotes a heat shield box.

A round steel slab having an outer diameter of 100 mm was placed in a heating furnace at 120
After the temperature is raised to 0 ° C., a rough die and a finish die are rolled, bent, and stamped by a forging press. After a deburring step, the crankshaft 2 obtained by the shaping die is moved to the V-shape.
It was loaded and mounted on blocks 3 and 3. The shape of the counterweight arm tip was measured.
To measure the shape of the arm of the counterweight of the crankshaft 2, the two shape measuring devices 5 are used, and the arm of the counterweight is set so as to sandwich the shape measuring device 5. The longitudinal direction (X direction) was the vertical direction (Y direction). The sectional shape of the tip of the arm of the counterweight was measured by laser projection. Laser projection was continuously performed at a pitch of 1 mm in the X direction to obtain a cross-sectional shape of 30 slices with one counterweight. The shape obtained by joining the cross-sectional shapes of 30 slices was defined as a measured cross-sectional shape. These data were transferred to the data processing device 7, and further subjected to a smoothing process to prevent the measurement accuracy from being deteriorated due to the unevenness of the data.

Next, the measured data input from the two shape measuring devices 5 to the data processing device 7 were subjected to shape inspection by superimposing the data of each unit with the reference shape. As shown in FIG. 2, the data processing device 7 includes two points p and q at positions 15 mm from the tip of the arm where no shape defect such as underfill occurs from among the reference shapes 9 stored in the storage unit 6 in advance. A total of three points were selected, one point r 5 mm away therefrom. In addition, the data processing device 7 detects three points p ′, q ′, and r ′ constituting the triangle such that the lengths of the three sides of the triangle formed by the three points are the same from the measured shape 10. That is, the data processing device 7 uses the reference shape 9
Triangle pq composed of three points p, q, and r selected from
r, three points p ′ extracted from the measured shape 10,
Three points p ′, q ′, r ′ are detected so that the three sides of the triangle p′q′r ′ composed of q ′, r ′ have the same length.

In the detection method, the absolute value of the difference in the length of each side of the triangle pqr composed of three points p, q, and r selected from the reference shape 9 with respect to the difference in the length of each corresponding side is determined in advance. If the value is equal to or smaller than the determined reference value ε (= 0.1 mm), the lengths of the three sides are determined to be the same, and the three points p ′, q ′, and r ′ are determined. | {(P−q) − (p′−q ′)} | ≦ 0.1 | {(q−r) − (q′−r ′)} | ≦ 0.1 | {(rp) − (R′−p ′)｝ | ≦ 0.1

Further, the data processing device 7 includes a reference shape 9
And three points p ′, q ′, and r ′ of the measured shape 10
The reference shape 9 and the measured shape 10 were overlapped so that each of r ′ matched. The result is shown in FIG. The data processing device 7 determines that the distance between the reference shape point and the measured shape point is 0.2.
The points (points s to t) that are apart from each other by mm or more are determined as the parts where the shape defect occurs, and the parts (points s to t) where the shape defect occurs are surrounded by the reference shape 9 and the measured shape 10. The calculated area was calculated as a shape defect area, and was compared with a predetermined allowable shape defect area to determine pass / fail. The data processing device 7 measures the shape of each counterweight portion of the operating crankshaft by the above-described method, and superimposes the reference shape 9 and the measurement shape 10 on the reference shape 9 and the measurement shape 10.
Was calculated as the shape defect area, and the pass / fail was determined by comparing the area with a predetermined allowable shape defect area.

Embodiment 2 Using the same crankshaft measuring device 1 as in Embodiment 1, FIG.
For the shape of the protrusion 11 shown in FIG. As shown in FIG. 4, the data processing device 7 selects, from among the reference shapes stored in advance in the storage unit 6,
Select points u, v, w, x. And the data processing device 7
Are four points u ′ forming a quadrangle such that the lengths of the four sides of the quadrangle uvwx formed by those four points are the same,
v ′, w ′, and x ′ are detected from the measured shape 12. That is, if the absolute value of the difference between the lengths of the corresponding sides is equal to or smaller than a predetermined reference value ε (= 0.1 mm), it is determined that the rectangles are geometrically identical. | {(Uv) − (u′−v ′)} | ≦ 0.1 | {(v−w) − (v′−w ′)} | ≦ 0.1 | ｛(w−x) − (W′−x ′)｝ | ≦ 0.1 | {(x−u) − (x′−u ′)} | ≦ 0.1

Further, the data processing device 7 executes the reference shape 1
3, four points u, v, w, x, and four points u ′ of the measurement shape 12,
The reference shape 13 and the measurement shape 12 are overlapped so that v ′, w ′, and x ′ match each other, and a portion where the distance between the reference shape 13 and the measurement shape 12 is 0.2 mm or more is formed. The area where the defect is generated is determined, and the area surrounded by the reference shape 13 and the measured shape 12 is calculated as the shape defect area for the area where the shape defect is generated, and is compared with a predetermined allowable shape defect area. And passed or failed.

Embodiment 3 FIG. 5 shows a crankshaft 21 manufactured by a twisting process (twister). FIG. 6 shows a cross section taken along line CC of FIG. Counterweights 23 to 25 are arranged at a distance of 120 ° from journal 22. With the crankshaft 2 of the first embodiment, the measurement can be performed by one scan in the X direction by using the crankshaft shape measuring device 1 of FIG. But,
Since the crankshaft shape measuring apparatus 1 shown in FIG. 1 moves linearly in the X direction, when measuring the shape of the counterweights 23 to 25 of the crankshaft 21 shown in FIG. The shape of the weight 23 is measured. After that, the crankshaft 21 on the V-block is rotated by 120 ° and scanning is performed, and the shape of the counterweight 24 is measured. The same operation must be repeated to measure the remaining counterweight 25. That is, it is necessary to perform three scans, and it takes a long time for measurement.

Therefore, a crankshaft shape measuring device which can measure the shape of the counterweights 23 to 25 in one scan was used. That is, the shapes of the shape measuring device 5 and the heat shield box 8 of FIG. 1 were arranged as shown in FIG.
FIG. 7 shows a plane perpendicular to the longitudinal direction of the crankshaft 21. Hereinafter, a measurement example of the shape of the counterweights 23 to 25 in FIG. 5 will be described. Since the counterweights 23 to 25 are arranged 120 ° apart in the vertical direction of the longitudinal direction of the crankshaft 21, a shape measuring device is used so that all the counterweights 23 to 25 can be measured in one scan. Must be located. In the present embodiment, six shape measuring devices 26 are arranged 26-1 to 26-6 on the same circumference of a section perpendicular to the longitudinal direction of the crankshaft 21 and the shape measuring device 26
Has a structure capable of moving on the rail 27.

Crankshaft 21 manufactured by twisting process
Was loaded and mounted on a V block. Then, the counterweights 23-1 and 23-2 are set by moving on the rail 27 so that the shape measuring devices 26-1 and 26-2, each of which is a two-dimensional laser distance meter, can measure. The position on the rail 27 to which the shape measuring device 26 moves is a value that is fixed depending on the type of product. Therefore, the position is automatically set from the type information stored in the storage unit 6 in advance. 4 remaining
Similarly, the counterweights 24-1 of the crankshaft 21 corresponding to the shape measuring devices 24-3 to 24-6,
It was set so that 24-2, 25-1, and 25-2 could be measured.

The measurement data obtained from each of the shape measuring devices 24-1 to 24-6 corresponding to each of the counterweights 23 to 25 was subjected to a shape inspection by overlapping with the reference shape by the data processing device as described above. . That is, FIG.
As shown in FIG. 2, the points j, j are formed such that two triangles are formed from the portions of the reference shape 91 where no shape defect occurs.
k, l and m, n, o were selected. And two triangles j
kl, triangles m'n'o 'and points j', k ', l' which make up triangle j'k'l 'and triangle m'n'o'
m ′, n ′, o ′ are replaced with the respective counterweights 23-1 to 23-1.
It was detected from the measurement shape of 25-2. As in the first embodiment, if the absolute value of the difference between the lengths of the corresponding sides is equal to or smaller than a predetermined reference value ε (= 0.1 mm) as in the first embodiment, a geometrically identical triangle is set, and j ′ , K ', l', m ', n', o '
Points were detected. In the subsequent data processing method, the area of the defective portion was calculated in the same manner as in Example 1, and the pass / fail of the product was determined by comparing the calculated area with a predetermined allowable value.

[0038]

According to a first aspect of the present invention, there is provided a crankshaft shape measuring method comprising the same number of polygons having the same geometric shape as a polygon formed from three or more points selected from a reference shape. Points are detected from the measured measurement shapes, the reference shape and the measurement shape are overlapped so that the polygons overlap, and the reference shape and the measurement shape are compared to inspect for shape defects. Inspection of shape defects can be automatically performed in a short time and with high accuracy.

According to a second aspect of the present invention, there is provided a crankshaft shape measuring device for measuring a product shape of a crankshaft, a memory for storing reference shape data, and a memory for storing reference shape data therein. At least three or more points are selected from a portion where a shape defect does not occur, and the same number of points that form a polygon having the same geometric shape as the polygon formed by the selected points are determined by the measurement device. It has a data processing device that detects from the measured measurement shape, superimposes the reference shape and the measurement shape so that the polygons overlap, compares the reference shape with the measurement shape, and performs pass / fail judgment. The crankshaft shape inspection can be automatically performed in a short time and with high accuracy. Furthermore, when this device is installed on a production line such as a forging press to perform hot measurement of the crankshaft, changes in shape quality due to fluctuations in operating conditions, etc. are continuously and immediately grasped immediately after stamping. Therefore, it is possible to suppress the occurrence of defective products by taking operational measures at an early stage.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a crankshaft shape measuring device used in Examples 1 and 2.

FIG. 2 is a schematic diagram of a result obtained by superimposing a reference shape and a measured shape in Example 1.

FIG. 3 is an explanatory diagram of a crankshaft shape having a protrusion according to a second embodiment.

FIG. 4 is a diagram showing a fourth example in which a quadrangular shape is formed on the protrusion in the second embodiment.
It is explanatory drawing of a point.

FIG. 5 is an overall front view of a six-cylinder crankshaft manufactured by a twisting process according to a third embodiment.

FIG. 6 is a sectional view taken along the line CC of FIG. 5;

FIG. 7 is an explanatory diagram of a schematic arrangement of a shape measuring device used in a third embodiment.

FIG. 8 is a flowchart of a crankshaft shape measuring method according to the present invention.

FIG. 9 is an explanatory diagram of selection of three points forming a triangle from a reference shape.

FIG. 10 is an explanatory diagram of superimposition of each point of a triangle of a reference shape and a measurement shape.

FIG. 11 is an explanatory diagram of superposition of square points of a reference shape and a measurement shape.

FIG. 12 is an explanatory diagram of selection of points forming two triangles from a reference shape.

FIG. 13 is a front view of a four-cylinder crankshaft.

FIG. 14 is a sectional view taken along line BB of FIG.

15A and 15B show an arm of a counterweight of a crankshaft. FIG. 15A is a side view, and FIG.
It is an enlarged view for explaining underfill of a part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crankshaft shape measuring device 2, 21, 101 Crankshaft 3 V block 4 Bed 5 Shape measuring device 6 Storage unit 7 Data processing device 8 Heat shield box 9, 13, 91, 111 Reference shape 10, 12, 92, 112 Measurement Shape 11 Protrusion 22, 104 Journal 23, 24, 25, 103 Counterweight 26 Shape measuring device 27 Rail 102 Pin

Claims (2)

[Claims] 1. A method for inspecting a shape of a crankshaft product, wherein at least three points are selected from at least a portion where a shape defect does not occur in a reference shape, and a plurality of points are formed from the selected points. Detects the same number of points that make up a polygon that is geometrically identical to the polygon from the measured measurement shape, superimposes the reference shape and the measurement shape so that the polygons overlap, and compares the reference shape and the measurement shape And a shape defect inspection method. 2. A shape measuring device for measuring a product shape of a crankshaft, a storage unit for storing reference shape data, and at least three or more parts of the reference shape in which no shape defect occurs. A point is selected, and the same number of points that form a polygon having the same geometric shape as the polygon composed of the selected points are detected from the measurement shape measured by the shape measurement device, and the polygon is detected. A crankshaft shape measuring device, comprising: a data processing device that superimposes a reference shape and a measured shape so that the reference shape and the measured shape overlap each other, and compares the reference shape and the measured shape to determine whether or not the result is acceptable.