Molded rotary body measurement system

Abstract

To provide a molded rotary body measurement system that minimizes the need for repetitive balancing.SOLUTION: A molded rotary body measurement system is provided, comprising a first measurement device configured to measure the mass of a molded rotary body at multiple mass measurement points arranged for each unit angle and determine whether a variation in the mass is within a range of a first threshold or not, and a second measurement device configured to measure an imbalance amount of the molded rotary body when the variation is within the range of the first threshold.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a measurement system for a cast rotating body.

Background Art

[0002] There is known a forged rotating body manufactured by so-called die forging in which a forging material is pressed by a pair of upper and lower dedicated dies to transfer the die shape. For example, a crankshaft of an engine is known as a forged rotating body. A forged rotating body that rotates at high speed, such as a crankshaft, needs to be accurately balanced around its axis in order to suppress vibration during rotation.

[0003] However, in the case of die forging, due to misalignment between the upper die and the lower die, the shape of the forged rotating body is likely to deviate from the designed shape. Therefore, in the case of die forging, rotational imbalance is likely to occur. Techniques for calculating the amount of imbalance of such rotational imbalance have been proposed. For example, a technique has been proposed in which the three-dimensional shape of a forged rotating body is measured to set a provisional center hole, and the amount of imbalance of the shape after simulating machining based on this provisional center hole is calculated (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, although components such as the engine flywheel rotate at high speed, unlike the above-described open-die forging, they are manufactured by die casting. Cast rotating bodies such as flywheels are prone to internal defects such as casting cavities and undercuts during the casting process, unlike in the case of forging. Such internal defects cannot be confirmed by three-dimensional shape measurement. Therefore, in the case of a cast rotating body, a balancing process is carried out in which a hole for correction provided in the cast rotating body is machined to correct rotational imbalance.

[0006] However, in the balancing process, high-precision balancing is required in order to reduce the man-hours for the operation of machining the correction hole. For example, after correcting the rotational imbalance, the amount of imbalance is measured, and if the measured amount of imbalance is not within the allowable range, operations such as correcting the rotational imbalance again are repeated. That is, if the balancing accuracy is low, the balancing may be repeated, increasing the man-hours.

[0007] Therefore, an object of the present invention is to provide a measurement system for a cast rotating body that suppresses the repetition of balancing.

Means for Solving the Problem

[0008] A measurement system for a cast rotating body according to the present invention includes a first measuring device that measures the mass of the cast rotating body at a plurality of mass measurement points arranged at each unit angle and determines whether the variation in the mass is within a range of a first threshold value, and a second measuring device that measures the amount of imbalance of the cast rotating body when the variation is within the range of the first threshold value.

[0009] In the above configuration, the first measuring device may measure the mass at three mass measurement points arranged every 120 degrees.

[0010] In the above configuration, the first measuring device may determine whether the variation is within the range of the first threshold value in a first case where the three masses are different from each other, or in a second case where any two of the masses are the same and the remaining one of the masses is different from any two of the masses.

[0011] In the above configuration, the unit angle may be less than 120 degrees, and the product of the unit angle and the number of the plurality of mass measurement points may be 360 degrees.

[0012] In the above configuration, when the amount of unbalance is out of the range of the second threshold value, a processing device for processing holes for unbalance correction provided in the cast rotating body may be further provided.

Effect of the Invention

[0013] According to the present invention, repeated balancing can be suppressed.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the present embodiment, a casting blank that is finished as a flywheel will be described as an example of a cast rotating body. However, the cast rotating body is not limited to a casting blank that is finished as a flywheel, and may be a disk-shaped cast rotating body such as a casting blank that is finished as a crank pulley, for example.

[0016] First, with reference to FIG. 1, the production process of the flywheel will be described. First, a casting process is performed (process P1). In the casting process, molten metal is poured into a mold of the flywheel. When the molten metal cools and solidifies, a casting blank, which is the finished product of the casting process, is taken out of the mold. The mold may be a metal mold or a sand mold.

[0017] Next, a shape correction process is performed (Process P2). In the shape correction process, the shape of the rough casting is corrected, and a removal process for reducing or eliminating shape variations is performed. The removal process is performed using, for example, a combination lathe for performing grinding or cutting. The imbalance due to shape variations in the rough casting can be predicted by, for example, measuring the three-dimensional shape.

[0018] Next, a mass measurement process is performed (Process P3). In the mass measurement process, the mass of the rough casting is measured. Although details will be described later, in the mass measurement process, the mass of the rough casting is measured at a plurality of mass measurement points arranged at each unit angle. For example, the mass of the rough casting is measured at three mass measurement points arranged every 120 degrees.

[0019] Next, a variation determination process is performed (Process P4). In the variation determination process, it is determined whether the variation in the mass of the rough casting measured at a plurality of mass measurement points is small. Whether the mass variation is small is determined based on a first threshold value representing the smallness of the variation. If the mass variation is within the range of the first threshold value (Process P4: YES), it is determined that the mass variation is small. If the mass variation is outside the range of the first threshold value (Process P4: NO), it is determined that the mass variation is large.

[0020] When the mass variation is large, a melting process is performed (Process P5). In the melting process, the rough casting is melted. That is, for the rough casting after the shape variation has been removed, if the mass variation is large, it is presumed that there are internal defects such as casting cavities and lack of meat in the rough casting. Such internal defects are difficult to discover by measuring the three-dimensional shape and are also difficult to discover visually. Therefore, such a rough casting is melted and returned to the molten metal, and reused in the above-described Process P1.

[0021] On the one hand, when the variation in mass is small, an imbalance measurement process is carried out (Process P6). In the imbalance measurement process, the imbalance amount of the rough casting is measured. The measurement of the imbalance amount is performed using a known imbalance measuring device that dynamically measures the imbalance amount.

[0022] Next, an imbalance amount determination process is carried out (Process P7). In the imbalance amount determination process, it is determined whether the imbalance amount of the rough casting is small. Whether the imbalance amount is small is determined based on a second threshold value representing the smallness of the imbalance amount. If the imbalance amount is within the range of the second threshold value (Process P7: YES), it is determined that the imbalance amount is small. If the imbalance amount is outside the range of the second threshold value (Process P7: NO), it is determined that the imbalance amount is large.

[0023] When the imbalance amount is large, an imbalance correction process is carried out (Process P8). In the imbalance correction process, operations such as grinding and cutting are performed on the holes for imbalance correction provided in the rough casting. Thereby, the rotational imbalance of the rough casting is corrected. In this way, the balancing of the rough casting is carried out. When the imbalance correction process is completed, Processes P6 and P7 are executed again. Therefore, Processes P6, P7, and P8 are repeated until the imbalance amount becomes small.

[0024] When the imbalance amount is small without performing the imbalance correction process, or when the imbalance amount becomes small after performing the imbalance correction process, this process including the casting process to the imbalance correction process ends. When this process ends, although not shown, a finishing process for finishing the rough casting into a flywheel as a product is carried out.

[0025] Thus, in this step, processes P3 and P4 are carried out to detect internal defects in the rough casting. Then, subsequent processes P6, P7, etc. are carried out only when the variation in the mass of the rough casting is small. Therefore, balancing for rough castings that may have internal defects is excluded, and as a result, repeated balancing is suppressed. When repeated balancing is suppressed, the man-hours required for balancing are reduced.

[0026] Referring to FIGS. 2 and 3, the measurement system ST for the cast rotating body will be described.

[0027] As shown in FIG. 2, the measurement system ST for the cast rotating body includes a first processing device 10, a mass measurement device 20, an unbalance measurement device 30, and a second processing device 40. The first processing device 10 is, for example, a milling machine, a combination lathe, a machining center, etc. for performing grinding or cutting. The second processing device 40 may be the same as or different from the first processing device 10.

[0028] The first processing device 10 is used in process P2. That is, in order to correct the shape of the rough casting 50, the first processing device 10 performs grinding or cutting on the rough casting 50. Thereby, burrs and the like attached to the rough casting 50 are removed, and the variation in the shape of the rough casting 50 disappears.

[0029] The mass measurement device 20 is used in processes P3 and P4. The mass measurement device 20 is an example of the first measurement device. The mass measurement device 20 statically measures the mass of the rough casting 50 at a plurality of mass measurement points in order to detect internal defects in the rough casting 50. The mass measurement device 20 determines the variation in mass based on the measurement results.

[0030] As shown in FIGS. 3(a) and (b), the mass measurement device 20 includes a plurality (specifically, three) of mass measurement points 21, 22, 23 called contacts and a base 24. Load cells 25, 26, 27 are arranged inside the base 24. The load cells 25, 26, 27 are respectively connected to the mass measurement points 21, 22, 23. The load cells 25, 26, 27 measure the mass of the rough casting 50 horizontally placed on the plurality of mass measurement points 21, 22, 23 via the mass measurement points 21, 22, 23.

[0031] Here, the plurality of mass measurement points 21, 22, 23 are arranged at predetermined unit angles with respect to the center O of the base 24. In this embodiment, since the number of mass measurement points 21, 22, 23 is three, the three mass measurement points 21, 22, 23 are arranged every 120 degrees. In this way, if the mass measurement device 20 includes at least three mass measurement points 21, 22, 23, the plurality of mass measurement points 21, 22, 23 can support the rough casting 50. Therefore, the mass measurement device 20 can determine the variation in the mass of the rough casting 50 with the smallest number of mass measurement points 21, 22, 23. Thereby, the processing load associated with the determination of the variation can be reduced.

[0032] In addition, the mass measurement device 20 determines whether the variation is within the range of the first threshold value in the first case where the three measured masses are different from each other. The mass measurement device 20 may also determine whether the variation is within the range of the first threshold value in the second case where any two of the measured masses are the same and the remaining one of the measured masses is different from any two of the measured masses. Depending on the number of internal defects occurring, it may correspond to the first case or the second case.

[0033] Also, although not shown, for example, the number of mass measurement points may be four. In this case, the four mass measurement points are arranged every 90 degrees. Also, the number of mass measurement points may be five. In this case, the five mass measurement points are arranged every 72 degrees. Further, the number of mass measurement points may be six. In this case, the six mass measurement points are arranged every 60 degrees. Thus, when the unit angle is less than 120 degrees, it is sufficient that the product of the unit angle and the number of a plurality of mass measurement points is 360 degrees. Thereby, the mass measuring device 20 can accurately determine the variation in the mass of the rough casting 50.

[0034] The unbalance measuring device 30 is used in steps P6 and P7. The unbalance measuring device 30 is an example of a second measuring device. The unbalance measuring device 30 dynamically measures the amount of unbalance of the rough casting 50 to be balanced, based on well-known techniques. The unbalance measuring device 30 determines whether or not the amount of unbalance is within the range of the second threshold value, based on the measurement result. Thereby, it is determined whether or not processing such as cutting for a hole for correcting unbalance is necessary for the rough casting 50.

[0035] The second processing device 40 is used in step P8. The second processing device 40 performs processing such as cutting for a hole for correcting unbalance when the amount of unbalance is out of the range of the second threshold value.

[0036] Thus, the measurement system ST of the cast rotating body includes the mass measuring device 20 and the unbalance measuring device 30. The mass measuring device 20 measures the mass of the rough casting 50 at a plurality of mass measurement points 21, 22, 23 arranged for each unit angle, and determines whether or not the variation in mass is within the range of the first threshold value. The unbalance measuring device 30 measures the amount of unbalance of the rough casting 50 when this variation is within the range of the first threshold value.

[0037] Thus, only when there is no (or little) possibility of internal defects in the rough casting 50 and the mass variation is small, the imbalance measuring device 30 measures the amount of imbalance of the rough casting 50. As a result, the repetition of balancing is suppressed, and the man-hours required for balancing are reduced.

[0038] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims. For example, if internal defects can be detected within a measurement time comparable to that of step P3, an X-ray scan may be applied to the rough casting 50 instead of the mass measuring device 20.

Explanation of Reference Numerals

[0039] ST Measuring System for Cast Rotating Body 10 First Processing Device 20 Mass Measuring Device 21, 22, 23 Mass Measurement Points 24 Base 25, 26, 27 Load Cells 30 Imbalance Measuring Device 40 Second Processing Device 50 Rough Casting

Claims

1. A first measuring device that measures the mass of a cast rotating body at a plurality of mass measurement points arranged at each unit angle and determines whether the variation in the mass is within the range of a first threshold value; A second measuring device that measures the amount of unbalance of the cast rotating body when the variation is within the range of the first threshold value; A measuring system for a cast rotating body comprising the same.

2. The first measuring device measures the mass at three mass measurement points arranged every 120 degrees. The measuring system for a cast rotating body according to Claim 1, characterized in that.

3. The first measuring device determines whether the variation is within the range of the first threshold value in a first case where the three masses are different from each other, or in a second case where any two of the masses are the same and the remaining one of the masses is different from any two of the masses. The measuring system for a cast rotating body according to Claim 2, characterized in that.

4. The unit angle is less than 120 degrees, and the product of the unit angle and the number of the plurality of mass measurement points is 360 degrees. The measuring system for a cast rotating body according to Claim 1, characterized in that.

5. When the amount of unbalance is outside the range of a second threshold value, the measuring system further comprises a processing device that processes holes for unbalance correction provided in the cast rotating body. The measuring system for a cast rotating body according to any one of Claims 1, 2, and 4, characterized in that.

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