Measurement system for rotating cast bodies
The measurement system for cast rotating bodies addresses internal defects by using mass and unbalance measuring devices with threshold checks, reducing the need for repeated balancing and associated man-hours.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-12-19
- Publication Date
- 2026-06-23
AI Technical Summary
Cast rotating bodies, such as engine flywheels, suffer from internal defects like casting defects and material loss, which cannot be detected by three-dimensional shape measurement, leading to repeated high-precision balancing processes that increase man-hours.
A measurement system that includes a first measuring device to assess mass variation at multiple points and a second device to measure unbalance, with threshold checks to minimize repeated balancing by detecting internal defects and unbalance accurately.
Reduces the need for repeated balancing operations, thereby decreasing the man-hours required for correcting rotational imbalance.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a measurement system for a cast rotating body.
Background Art
[0002] Forged rotating bodies 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, are known. For example, the 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 vibrations 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 processing 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, engine flywheels and other components also rotate at high speeds, but unlike the die forging described above, they are manufactured by die casting. Unlike forged products, cast rotating bodies such as flywheels are prone to internal defects such as casting defects and material loss during the casting process. Such internal defects cannot be detected by measuring the three-dimensional shape. Therefore, in the case of cast rotating bodies, a balancing process is carried out to correct rotational imbalance by machining correction holes provided in the cast rotating body.
[0006] However, the balancing process requires high-precision balancing to reduce the man-hours required for machining correction holes. For example, after correcting rotational unbalance, the amount of unbalance is measured, and if the measured amount of unbalance is not within the acceptable range, the rotational unbalance is corrected again. This process is repeated. In other words, if the balancing accuracy is low, the balancing process will have to be repeated, potentially increasing the man-hours required.
[0007] Therefore, the present invention aims to provide a measurement system for a rotating cast body that suppresses the repeated balancing process. [Means for solving the problem]
[0008] The casting rotation body measurement system according to the present invention includes a first measuring device that measures the mass of the casting rotation body at a plurality of mass measuring points arranged at unit angle intervals and determines whether the variation in the mass is within a first threshold range, and a second measuring device that measures the amount of unbalance of the casting rotation body if the variation is within the first threshold range.
[0009] In the above configuration, the first measuring device may measure the mass at three mass measuring points arranged at 120-degree intervals.
[0010] In the above configuration, the first measuring device may determine whether the variation is within the range of the first threshold in the first case where the three masses are different from each other, or in the second case where any two of the masses are the same and the remaining mass 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, if the amount of unbalance falls outside the range of a second threshold, the system may further include a machining device for machining an unbalance correction hole provided in the casting rotating body. [Effects of the Invention]
[0013] According to the present invention, repeated balancing can be suppressed. [Brief explanation of the drawing]
[0014] [Figure 1] This is a process flow diagram illustrating an example of a production process for a cast rotating body. [Figure 2] This is an example of a measurement system for rotating cast bodies. [Figure 3] (a) is an example of a plan view of a mass measuring device. (b) is an example of a front view of a mass measuring device. [Modes for carrying out the invention]
[0015] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In this embodiment, a casting material that will be 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 material that will be finished as a flywheel, and may be a disc-shaped cast rotating body such as a casting material that will be finished as a crank pulley.
[0016] First, with reference to Figure 1, the flywheel production process will be explained. First, the casting process is carried out (process P1). In the casting process, molten metal is poured into the flywheel mold. Once the molten metal cools and solidifies, the finished product of the casting process, the raw casting, is removed from 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 machining process is performed to reduce or eliminate variations in the shape. The machining process is performed using, for example, a combination lathe for performing grinding or cutting. The imbalance due to variations in the shape of 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 for 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 variation in mass is small is determined based on a first threshold value representing the smallness of the variation. If the variation in mass is within the range of the first threshold value (Process P4: YES), it is determined that the variation in mass is small. If the variation in mass is outside the range of the first threshold value (Process P4: NO), it is determined that the variation in mass is large.
[0020] If the variation in mass 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 variation in shape has been removed, if the variation in mass 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 detect by measuring the three-dimensional shape and are also difficult to detect visually. Therefore, such a rough casting is melted and returned to the molten metal, and is reused in the above-described Process P1.
[0021] On the one hand, when the mass variation 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 provided in the rough casting for imbalance correction. Thereby, the rotational imbalance of the rough casting is corrected. Thus, the balancing of the rough casting is carried out. When the imbalance correction process ends, 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 in the figure, a finishing process for finishing the rough casting into a flywheel as a product is carried out.
[0025] Thus, in this process, steps P3 and P4 are performed to detect internal defects in the raw casting material. Then, subsequent steps P6 and P7 are performed only if the mass variation of the raw casting material is small. Therefore, balancing of raw casting material that may have internal defects is excluded, and as a result, the number of repeated balancing operations is reduced. Reducing the number of repeated balancing operations reduces the man-hours required for balancing.
[0026] The measurement system ST for a rotating cast body will be described with reference to Figures 2 and 3.
[0027] As shown in Figure 2, the casting rotating body measurement system ST comprises a first processing device 10, a mass measuring device 20, an unbalance measuring device 30, and a second processing device 40. The first processing device 10 is, for example, a milling machine, a multi-tasking lathe, or a machining center for 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. Specifically, in order to correct the shape of the raw casting material 50, the first processing device 10 performs grinding, cutting, etc. on the raw casting material 50. As a result, burrs and other debris attached to the raw casting material 50 are removed, and variations in the shape of the raw casting material 50 are eliminated.
[0029] The mass measuring device 20 is used in processes P3 and P4. The mass measuring device 20 is an example of a first measuring device. The mass measuring device 20 statically measures the mass of the raw casting 50 at multiple mass measuring points in order to detect internal defects in the raw casting 50. Based on the measurement results, the mass measuring device 20 determines the variation in mass.
[0030] As shown in Figures 3(a) and (b), the mass measuring device 20 includes a base 24 and a plurality (specifically three) mass measuring points 21, 22, and 23 called contacts. Load cells 25, 26, and 27 are arranged inside the base 24. The load cells 25, 26, and 27 are connected to the mass measuring points 21, 22, and 23, respectively. The load cells 25, 26, and 27 measure the mass of the raw casting material 50, which is placed horizontally on the plurality of mass measuring points 21, 22, and 23, via the mass measuring points 21, 22, and 23.
[0031] Here, the multiple mass measurement points 21, 22, and 23 are arranged at predetermined unit angle intervals with respect to the center O of the base 24. In this embodiment, since there are three mass measurement points 21, 22, and 23, the three mass measurement points 21, 22, and 23 are arranged at 120-degree intervals. In this way, as long as the mass measuring device 20 is equipped with at least three mass measurement points 21, 22, and 23, the multiple mass measurement points 21, 22, and 23 can support the casting material 50. Therefore, the mass measuring device 20 can determine the mass variation of the casting material 50 with the fewest number of mass measurement points 21, 22, and 23. This reduces the processing load associated with determining the variation.
[0032] The mass measuring device 20 determines whether the variation is within the first threshold range when the three measured masses are different from each other (case 1). The mass measuring device 20 may also determine whether the variation is within the first threshold range when two of the measured masses are the same and the remaining measured mass is different from the other two (case 2). Depending on the number of internal defects that occur, the case may fall under either case 1 or case 2.
[0033] Furthermore, although not shown in the diagram, the number of mass measurement points may be four, for example. In this case, the four mass measurement points are arranged at 90-degree intervals. Alternatively, the number of mass measurement points may be five, in which case the five mass measurement points are arranged at 72-degree intervals. In addition, the number of mass measurement points may be six, in which case the six mass measurement points are arranged at 60-degree intervals. Thus, when the unit angle is less than 120 degrees, the product of the unit angle and the number of mass measurement points should be 360 degrees. This allows the mass measuring device 20 to determine the variation in the mass of the raw casting material 50 with high accuracy.
[0034] The unbalance measuring device 30 is used in processes P6 and P7. The unbalance measuring device 30 is an example of a second measuring device. Based on well-known technology, the unbalance measuring device 30 dynamically measures the amount of unbalance of the casting material 50 to be corrected. Based on the measurement results, the unbalance measuring device 30 determines whether the amount of unbalance is within the range of a second threshold. This allows for the determination of whether processing, such as cutting holes to correct the unbalance, is necessary for the casting material 50.
[0035] The second processing device 40 is used in process P8. The second processing device 40 performs machining, such as cutting a hole to correct the imbalance, when the amount of imbalance falls outside the range of the second threshold.
[0036] Thus, the casting rotating body measurement system ST comprises a mass measuring device 20 and an unbalance measuring device 30. The mass measuring device 20 measures the mass of the raw casting material 50 at a plurality of mass measuring points 21, 22, 23 arranged at unit angle intervals, and determines whether the variation in mass is within a first threshold range. The unbalance measuring device 30 measures the amount of unbalance of the raw casting material 50 if this variation is within the first threshold range.
[0037] As a result, the unbalance measuring device 30 measures the amount of unbalance in the casting material 50 only when there is little to no possibility of internal defects in the casting material 50 and the mass variation is small. This reduces the need for repeated balancing and lowers the amount of work required for balancing.
[0038] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims. For example, if internal defects can be detected in a measurement time similar to that of process P3, an X-ray scan may be applied to the casting material 50 instead of the mass measuring device 20. [Explanation of symbols]
[0039] ST Casting Rotation Body Measurement System 10 1st processing device 20 Mass measuring device 21,22,23 Mass measurement point 24 base 25, 26, 27 Load Cells 30. Unbalance measuring device 40 Second processing device 50 Cast Iron Raw Material
Claims
1. A first measuring device that measures the mass of a rotating cast body at multiple mass measuring points arranged at unit angle intervals and determines whether the variation in the mass is within a first threshold range, If the variation is within the range of the first threshold, a second measuring device for measuring the amount of unbalance of the casting rotating body, A measuring system for a rotating cast body.
2. The first measuring device measures the mass at three mass measuring points arranged at 120-degree intervals. The casting rotating body measurement system according to feature 1.
3. The first measuring device determines whether the variation is within the range of the first threshold in the first case where the three masses are different from each other, or in the second case where any two of the masses are the same and the remaining mass is different from any two of the masses. The casting rotating body measurement system according to feature 2.
4. The unit angle is less than 120 degrees, and the product of the unit angle and the number of the multiple mass measurement points is 360 degrees. The casting rotating body measurement system according to feature 1.
5. If the amount of unbalance falls outside the range of a second threshold, the system further includes a machining device for machining an unbalance correction hole provided in the rotating cast body. A measuring system for a rotating cast body according to any one of claims 1, 2, or 4.