JP6797745B2 - Center hole determination device - Google Patents

Description

The present invention relates to a center hole determining device.

Since the crankshaft is used by being incorporated in the engine, if there is an unbalanced amount of rotation, problems such as vibration during engine rotation occur. Therefore, it is necessary to suppress the amount of rotation imbalance of the crankshaft.

To reduce the amount of rotational imbalance of the crankshaft, accurately grasp the actual shape of the material crankshaft before processing, calculate the moment of inertia spindle that is the optimum balance in the finished product state, and place the material crank on the calculated moment of inertia spindle. It is important to form a center hole that serves as a machining standard for the shaft.

Here, Patent Document 1 proposes a method of interpolating an error due to a deviation between an upper mold and a lower mold used for molding a material crankshaft for the purpose of accurately reproducing the actual shape of the material crankshaft. There is. In Patent Document 1, the inertial spindle of the material crankshaft is obtained by regarding each of the upper die region, the lower die region, and the intermediate region interpolated between the upper die region and the lower mold region as mass points in the counterweight. Is required.

Japanese Unexamined Patent Publication No. 2010-031987

By the way, the crankshaft in the finished product state may be provided with notches such as oil holes and keyways. In addition, there are some crankshafts for in-line 3-cylinder engines that are designed so that the rotation can be balanced with the connecting rod attached to the pin journal instead of the crankshaft alone.

However, in the method of Patent Document 1, only each region of the counterweight is regarded as a mass point, and the main axis of inertia is required. Therefore, if the material crankshaft is notched in the subsequent process, or if the rotation balance cannot be achieved without attaching a heavy object to the crankshaft, the inertial spindle of the finished crankshaft will be the material crankshaft. It deviates from the main axis of inertia. Therefore, in the method of Patent Document 1, there is a limit in suppressing the amount of rotational imbalance of the crankshaft.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a center hole determining device for a material crankshaft capable of suppressing a rotational imbalance amount of the crankshaft.

The center hole determining device according to the present invention is for determining the center hole of a material crankshaft having at least one counterweight, and has a positive mass point corresponding to the counterweight and a cut provided on the material crankshaft. It is provided with an inertial spindle setting section that sets the inertial spindle of the material crankshaft based on the negative mass points corresponding to the notches and / or the positive mass points corresponding to the heavy objects attached to the material crankshaft.

According to the present invention, it is possible to provide a center hole determining device for a material crankshaft capable of suppressing a rotational imbalance amount of the crankshaft.

Material Side view of an example of a crankshaft. Material Crankshaft processing system configuration diagram. The figure which shows the design shape and the actual shape of a counterweight. The figure for demonstrating the best fit of the design shape of a counterweight to the actual shape. The figure for demonstrating expansion / contraction of each division area of a counterweight. External perspective view of an example of a crankshaft in a finished product state. The figure for demonstrating the correction method of the moment of inertia spindle.

[Material Crankshaft 1]
FIG. 1 is an example of a material crankshaft 1, and here, a material crankshaft for an in-line 3-cylinder engine is shown. The material crankshaft 1 is formed, for example, by forging or casting.

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

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

The crankshaft processing system 100 determines the positions of the center hole processing machine 10 as an example of processing means for processing center holes on both end surfaces of the material crankshaft 1 and the positions of the center holes processed on both end surfaces of the material crankshaft 1. It has a center hole determining device 20 for performing predetermined processing, and a crankshaft processing machine 30 for performing predetermined processing on a material crankshaft in which a center hole is machined.

The center hole processing machine 10 includes 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 meter such as a laser displacement meter, an infrared displacement meter, and an LED displacement sensor, or a contact type displacement meter such as an actuating transformer, and is based on the measured value from the displacement meter. Material Measure the shape of the crank shaft 1. In the present embodiment, the shape measuring machine 11 measures only the outer shape of each counterweight CW of the material crankshaft 1.

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 target from a plurality of different positions.

The center hole determining device 20 is a processing device for determining the positions of center holes machined on both end faces of the material crankshaft 1. The center hole determination device 20 includes a CPU (Central Processing Unit) 21, a ROM (Read Only Memory) 22, and a RAM (Random Access Memory) 23.

The ROM 22 stores various programs and various information to be executed by the CPU 21. In the present embodiment, the ROM 22 stores a processing program for determining the position of the center hole of the material crankshaft 1, which will be described later. Further, the ROM 22 stores design shape data indicating the design shape of each of the six counterweight CWs 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.

When the CPU 21 reads the program stored in the ROM 22 into the RAM 23 and executes the process, the center hole determination device 20 has the actual shape data acquisition unit 20a and the moment of inertia calculation unit 20 as shown in FIG. 2 (b). It functions as a correction unit 20b, a correction unit 20c, an inertial spindle setting unit 20d, an inertial spindle correction unit 20e, and a center hole determination unit 20f.

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

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

The shape measuring machine 11 measures the shape of each counterweight CW. Specifically, the shape measuring machine 11 measures the outer peripheral contour position of each counterweight CW, as shown by ● in FIG. As a result, the shape measuring machine 11 generates actual shape data indicating the two-dimensional actual shape of each counterweight CW. Note that the measurement positions are schematically shown in FIG. 3, and the measurement may actually be performed at more positions than ● shown in FIG.

As a method of measuring the shape of each counter weight CW, for example, a method of fixing a displacement meter and measuring while rotating the material crankshaft 1, a method of fixing the material crankshaft 1 and placing a displacement meter around it. 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 can be mentioned, but the present invention is not limited to this.

<Expansion rate calculation unit 20b>
The expansion / contraction ratio calculation unit 20b acquires design shape data indicating the design shape of each counterweight CW of the material crankshaft 1 from the ROM 22. 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 deviate from the position and angle of the design shape. In FIG. 3, the design shape is shown by a solid line, but the actual design shape is shown by a large number of polar coordinates. The number of polar coordinates is not particularly limited, but for example, 360 can be set at equal angles around the center P1 of the counterweight CW.

Here, as shown in FIG. 3, a plurality of divided region DRs are set around the center P1 of the counterweight CW in the design shape. Each divided area is substantially fan-shaped. The number of divided region DRs is not particularly limited, but in FIG. 3, 32 are set at an equal angle (11.25 degrees) around the center P1 of the counterweight CW. The center P1 of the counterweight CW is the geometric center of the counterweight CW in a plan view. The design shape data includes the coordinates (x, y, z) of the center of gravity Q1 of each divided region DR (only one center of gravity Q1 is shown in FIG. 3) and the volume V of each divided region R. The expansion / contraction ratio calculation unit 20b stores the coordinates (x, y, z) of the center of gravity Q1 and the volume V in association with each other for all the divided region DRs. 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, the expansion / contraction ratio calculation unit 20b moves and / or rotates the design shape so as to match the actual shape by using the best fit method, thereby causing an error between the design shape and the actual shape. Find the position where the sum of squares of is minimized. 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 compares 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 angle displacement M3 to coordinate the coordinates (x', y) of the center of gravity Q2 of each division region DR after the best fit. ', z) is calculated. The expansion / contraction ratio calculation unit 20b 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 in association with each other. The z-coordinate of the center of gravity Q2 of each divided region DR after the best fit is the same as the z-coordinate of the center of gravity Q1 of each divided region 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.

In addition, in FIG. 4, only one divided region DR in the design shape after the best fit is shown in order to show the positional relationship between the center of gravity Q1 and the center of gravity Q2. As shown, 32 divided region DRs 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. Find the error value a between the two in the radial direction around the center. 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 expansion / contraction ratio U (= T / S) is obtained by dividing by the total length S. As will be described later, the expansion / contraction ratio U is used to expand / contract each divided region DR so as to match the actual shape of the counterweight CW in the radial direction. In the examples shown in FIGS. 5A to 5C, since the plot of the actual shape is located outside in the radial direction of the division region DR, the expansion / contraction ratio U is larger than 1, but the plot of the actual shape is the division region. When it is located inside the radial direction of the DR, the expansion / contraction ratio U is smaller than 1.

<Correction unit 20c>
The correction unit 20c corrects the coordinates (x', y', z) of the center of gravity Q2 of each divided region DR after the best fit based on the expansion / contraction ratio U. Specifically, the correction unit 20c obtains the correction coordinates (x'x U, y'x 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.

Further, the correction unit 20c corrects the volume V of each divided region DR after the best fit based on the expansion / contraction ratio U. Specifically, the correction unit 20c obtains the 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 synonymous with correcting the mass (multiplication value of volume V and material density) of each divided region DR.

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

In this way, by expanding and contracting the size of the divided region DR based on the expansion and contraction ratio U (expanding in FIGS. 5A to 5C), the divided region DR is expanded and contracted as a whole to the plot position of the actual shape. Can be made to. This means that the design shape of the counterweight CW is matched to the actual shape for each division region DR. Therefore, the actual shape of the counterweight CW can be easily and accurately reproduced.

The correction unit 20c obtains 32 sets of correction coordinates (x'x U, y'x U, z) and a correction mass M for each counterweight CW. Therefore, the combination of the correction coordinates (x'x U, y'x U, z) and the correction mass M is 32 x 6 = 192 sets per one material crankshaft 1 (32 sets for every 6 counterweight CWs). ).

<Inertia spindle setting unit 20d>
The moment of inertia spindle setting unit 20d sets each counterweight CW to a mass point having a positive mass (hereinafter referred to as “positive mass point”), and the holes and grooves provided in the material crank shaft 1 in a subsequent step have a negative mass. (Hereinafter, referred to as “negative mass point”) is set to a mass point having the above, and a heavy object attached to each pin journal P in a subsequent step is set to a positive mass point. Then, the moment of inertia spindle setting unit 20d sets the moment of inertia spindle of the material crankshaft 1 based on the set positive and negative mass points.

Here, FIG. 6 is a side view showing the configuration of the crankshaft 1a in the finished product state. The crankshaft 1a is a crankshaft for an in-line 3-cylinder engine. The crankshaft for an in-line 3-cylinder engine is designed so that the rotation can be balanced with the connecting rod attached to each pin journal P. That is, in the crankshaft 1a, the connecting rod attached to each pin journal P functions as a heavy object for balancing rotation.

As shown in FIG. 6, the crankshaft 1a has three oil holes D (D1 to D3) and one keyway E1. The oil holes D1 to D3 and the keyway E1 are examples of "notches" provided in the material crankshaft 1. The oil hole D1 penetrates the main journal J1, the counterweight CW1 and the pin journal P1, and opens on the outer peripheral surfaces of the main journal J1 and the pin journal P1. The oil hole D2 penetrates the main journal J2, the counterweight CW3, and the pin journal P2, and opens on the outer peripheral surfaces of the main journal J2 and the pin journal P2. The oil hole D3 penetrates the main journal J3, the counterweight CW5, and the pin journal P3, and opens on the outer peripheral surfaces of the main journal J3 and the pin journal P3. The keyway E1 is formed on the outer peripheral surface of the main journal J1. The keyway E1 is provided in the crankshaft processing machine 30 for determining the rotation phase.

The inertial spindle setting unit 20d has the center of gravity coordinates R1 to R3 of the oil holes D1 to D3 based on the positions of the oil holes D1 to D3, the volumes of the oil holes D1 to D3, and the material density of the material crankshaft 1. Find the negative masses N1 to N3. The negative masses N1 to N3 are values obtained by multiplying the volume of each oil hole D1 to D3 by the material density.

The moment of inertia spindle setting unit 20d obtains a negative mass N4 at the barycentric coordinates R4 of the keyway E1 based on the position of the keyway E1 and the volume of the keyway E1 and the material density of the material crankshaft 1. The negative mass N4 is a value obtained by multiplying the volume of the keyway E1 by the material density.

The inertial spindle setting unit 20d obtains positive masses N5 to N7 at the center of gravity coordinates R5 to R7 of each pin journal P1 to P3. Further, the inertial spindle setting unit 20d obtains positive masses N8 to N10 at the center of gravity coordinates R8 to R10 of the heavy objects (connecting rods) attached to the pin journals P1 to P3. The positive masses N8 to N10 are preset according to the mass of each connecting rod.

The moment of inertia spindle setting unit 20d sets the positive mass points of the 192 (= 32 × 6) division region DRs to the positive mass points of the six counter weights CW, and sets the center of gravity coordinates R5 to R7 of each pin journal P to the mass N5. The positive mass points of ~ N7 are set, and the center of gravity coordinates R8 to R10 of each conrod are set to the positive mass points of masses N8 to N10. Further, the moment of inertia spindle setting unit 20d sets the barycentric coordinates R1 to R3 of the oil holes D1 to D3 to negative mass points N1 to N3, and sets the barycentric coordinates R4 of the key groove E1 to the negative mass points N4. Set to.

The moment of inertia spindle setting unit 20d has a positive mass point corresponding to the counter weight CW, a negative mass point corresponding to each oil hole D1 to D3 and a keyway E1, a positive mass point corresponding to each pin journal, and a weight. The moment of inertia principal axis of all mass points is obtained by solving a three-dimensional linear equation from the condition that the moment of inertia product around the moment of inertia principal axis is 0 (zero) based on the positive mass points corresponding to the object.

In the inertial spindle set in this way, the notch provided in the subsequent process is added as a negative mass point, and the heavy object attached to each pin journal P in the completed state is added as a positive mass point. Therefore, the inertial spindle of the crankshaft 1a can be predicted more accurately than in the case where only each counterweight CW is regarded as a positive mass point and the inertial spindle is obtained. Therefore, since it is possible to prevent the inertial spindle of the crankshaft 1a from deviating from the inertial spindle of the material crankshaft 1, the amount of rotational imbalance of the crankshaft 1a can be effectively suppressed.

<Inertia spindle correction part 20e>
The outer circumference of each counterweight CW of the material crankshaft 1 may be cut in a subsequent process so as not to interfere with the inner surface of the crankcase when it is housed in the crankcase. In this case, since the mass of each counterweight CW is reduced, the inertial spindle of the crankshaft 1a may deviate from the inertial spindle set by the inertial spindle setting unit 20d. Therefore, the inertial spindle correction unit 20e predicts the outer peripheral cutting amount of each counterweight CW in the subsequent process, and corrects the inertial spindle set by the inertial spindle setting unit 20d.

First, the inertial spindle correction unit 20e acquires the equations of x and y indicating the inertial spindle set by the inertial spindle setting unit 20d, and acquires the actual shape data from the actual shape data acquisition unit 20a. Then, as shown in FIG. 7, the inertial spindle correction unit 20e plots the inertial spindle on the actual shape of the counterweight CW. In FIG. 7, the moment of inertia spindle deviates from the geometric center of the design shape, but may overlap with the geometric center of the design shape.

Next, the inertial spindle correction portion 20e cuts the counterweight CW that may interfere with the inner surface of the crankcase when the material crankshaft 1 is rotated around the inertial spindle set by the inertial spindle setting unit 20d. Set the planned area X. The planned cutting area X is an area that needs to be cut in a subsequent process in order to prevent the counterweight CW from interfering with the inner surface of the crankcase. When the geometric center of the design shape is aligned with the inertial spindle set by the inertial spindle setting unit 20d, the inertial spindle correction portion 20e cuts a region (hatched portion in FIG. 7) of the actual shape that protrudes from the design shape. It shall be set in the planned area X.

Next, the inertial spindle correction unit 20e obtains a negative mass N11 in the barycentric coordinates R11 of the planned cutting area X based on the position of the planned cutting area X, the volume of the planned cutting area X, and the material density of the material crankshaft 1. Set. The negative mass N11 is a value obtained by multiplying the volume of the planned cutting region X by the material density.

Next, the moment of inertia spindle correction unit 20e is set by the moment of inertia spindle setting unit 20d in a state where the planned cutting area X is set to a negative mass point in addition to the positive and negative mass points set by the moment of inertia spindle setting unit 20d. The amount of rotational imbalance [g · cm] when the material crank shaft 1 is rotated around is calculated.

When the rotation unbalance amount is equal to or less than a predetermined threshold value, the moment of inertia spindle correction unit 20e outputs the moment of inertia spindle set by the moment of inertia spindle setting unit 20d to the center hole determination unit 20f as it is.

When the rotation unbalance amount is larger than a predetermined threshold value, the moment of inertia spindle correction unit 20e does not output the moment of inertia spindle set by the inertial spindle setting unit 20d to the center hole determination unit 20f, and proceeds with the following processing.

When the amount of rotational unbalance is larger than a predetermined threshold, the moment of inertia correction unit 20e shifts the moment of inertia set by the moment of inertia setting unit 20d in a direction in which the amount of rotational unbalance becomes smaller. To set.

Next, the inertial spindle correction unit 20e sets a planned cutting area X'of the counterweight CW that may interfere with the inner surface of the crankcase when the material crankshaft 1 is rotated around the set temporary inertial spindle. Reset the settings. The planned cutting area X'can be set in the same manner as the above-mentioned planned cutting area X.

Next, the inertial spindle correction portion 20e is negative in the barycentric coordinates R11'of the planned cutting area X'based on the position of the planned cutting area X', the volume of the planned cutting area X', and the material density of the material crankshaft 1. Reset the mass N11'of.

Next, the inertial spindle correction unit 20e is provided with a material crankshaft 1 around the temporary inertial spindle in a state where the planned cutting area X'is set to a negative mass point in addition to the positive and negative mass points set by the inertial spindle setting unit 20d. Recalculate the amount of rotation imbalance [g · cm] when the is rotated.

When the rotation unbalance amount is equal to or less than a predetermined threshold value, the inertial spindle correction unit 20e outputs the temporary inertial spindle as the corrected inertial spindle to the center hole determination unit 20f.

When the rotational unbalance amount is larger than the predetermined threshold value, the inertial spindle correction unit 20e once discards the temporary inertial spindle until a temporary inertial spindle whose rotational unbalance amount is equal to or less than the predetermined threshold value is found. The process is repeated. As a result, when a temporary moment of inertia spindle whose rotational unbalance amount is equal to or less than a predetermined threshold value is found, the moment of inertia spindle correction unit 20e outputs the temporary moment of inertia spindle as a corrected moment of inertia spindle to the center hole determination unit 20f. To do.

<Center hole determination unit 20f>
The center hole determination unit 20f acquires either the inertial spindle set by the inertial spindle setting unit 20d or the corrected inertial spindle corrected by the inertial spindle correction unit 20e from the inertial spindle correction unit 20e. The center hole determination unit 20f obtains the center hole position by substituting the z-axis coordinates of the axial end surface positions of the material crankshaft into the x and y equations of the inertial spindle obtained from the inertial spindle correction unit 20e.

The center hole position determined in this way is sent to the center hole processing machine 10, and the center hole is machined at both end surface positions of the material crankshaft 1. After that, the material crankshaft 1 in which the center hole is formed is mainly processed in the journal portion in the crankshaft processing machine 30.

[Other Embodiments]
(1) In the above embodiment, the case where the material crankshaft 1 for the in-line 3-cylinder engine is used has been described, but the present invention is not limited to this. The material crankshaft may be for an in-line 4-cylinder engine, an in-line 6-cylinder engine, a V-type 6-cylinder engine, a V-type 8-cylinder engine, or the like. However, in the material crankshaft for an in-line 4-cylinder engine or an in-line 6-cylinder engine, it is not necessary to make the connecting rod attached to each pin journal P function as a weight for balancing the rotation of the crankshaft. Therefore, when determining the moment of inertia spindle of the material crankshaft for an in-line 4-cylinder engine or an in-line 6-cylinder engine, the weights (connecting rods) provided on the pin journals P1 to P3 and the pin journals P1 to P3 are positive. It does not need to be set as a mass point.

(2) In the above embodiment, the inertia spindle setting unit 20d does not regard each counterweight CW as one positive mass point, but regards each counterweight CW as an aggregate of positive mass points for each of a plurality of division region DRs, and regards the material crank. It was decided to set the inertial spindle of the shaft 1, but the present invention is not limited to this. The inertial spindle setting unit 20d may regard each counterweight CW as one positive mass point, or may be regarded as an aggregate of positive mass points that are divided differently from the plurality of division region DRs. For example, as described in Japanese Patent Application Laid-Open No. 2010-031987, the moment of inertia spindle setting unit 20d sets the mass points of each counterweight CW as the mass points of the upper mold region, the mass points of the lower mold region, and the upper mold region and the lower mold region. It may be regarded as an aggregate with the mass points of the intermediate region interpolated between the type regions.

(3) In the above embodiment, when the moment of inertia spindle of the material crankshaft 1 is obtained, three oil holes D and one key groove E1 are set as negative mass points, but other holes and grooves are set in the material crankshaft 1. If is provided, it may be set separately as a negative mass point. The number of oil holes and keyways can be changed as appropriate.

(4) In the above embodiment, the crankshaft 1a is provided with a "notch" and a "heavy object" is attached, but only one of them may be provided.

(5) In the above embodiment, each counterweight CW is divided into 32 divided area DRs, but the number of divided area DRs can be appropriately set, and the number of divided area DRs is the counterweight CW. It may be different for each.

(6) In the above embodiment, each counterweight CW is divided into equal-angle division region DRs, but the division region DRs may not be set at equal angles.

1 Material Crankshaft 20a Actual shape data acquisition unit 20b Expansion / contraction rate calculation unit 20c Correction unit 20d Moment of inertia spindle setting unit 20e Moment of inertia spindle correction unit 20f Center hole determination means CW Counterweight P1 Center of counterweight before best fit P2 After best fit Center of counterweight DR Divided area Q1 Center of gravity of divided area before best fit Q2 Center of gravity of divided area after best fit U Moment of inertia

Claims (3)

A center hole determining device for determining the center hole of a material crankshaft having at least one counterweight.
Based on the positive mass corresponding to the counterweight, the negative mass corresponding to the notch provided in the material crankshaft, and / or the positive mass corresponding to the heavy object attached to the material crankshaft. , A center hole determining device for a material crankshaft, comprising an inertial spindle setting unit for setting the inertial spindle of the material crankshaft. A moment of inertia spindle correction part for correcting the moment of inertia spindle set by the inertial spindle setting part is provided.
The inertial spindle correction unit is an inertial spindle set by the inertial spindle setting unit based on a negative mass point corresponding to a planned cutting area of the counterweight obtained based on the actual shape and the design shape of the counterweight. To fix,
The material crankshaft center hole determining device according to claim 1. In the moment of inertia spindle correction portion, the amount of rotational unbalance when the material crank shaft to which the negative mass point corresponding to the planned cutting region is added is rotated around the moment of inertia spindle set by the moment of inertia spindle setting portion. The moment of inertia spindle set by the moment of inertia spindle setting unit is modified so as to be smaller.
The material crankshaft center hole determining device according to claim 2.

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