JP4415680B2 - Grinding apparatus and grinding method - Google Patents

Description

  The present invention relates to a grinding apparatus and a grinding method for grinding a shaft-like workpiece provided with an eccentric member at a position eccentric with respect to a rotating shaft.

  For example, the cam lobe portion of the camshaft or the pin portion of the crankshaft is lapped after grinding because a highly smooth finished surface is required. In this way, if the machining process changes from grinding to lapping, the workpiece must be transferred to a different machining facility each time, resulting in longer machining time, more processes and machining equipment, and inevitably. Processing costs also increase. Therefore, if a highly smooth finished surface can be obtained, it is preferable that the processing is completed only by grinding.

  To finish a highly smooth surface by grinding alone, the workpiece must be rotated at high speed, but an axial workpiece such as a crankshaft with an eccentric member provided at an eccentric position relative to the rotation axis. When rotating at a high speed around the rotation axis, a large eccentric load is applied, and it is difficult to correct the rotation balance for each crankshaft.

  Therefore, there is also an apparatus for grinding the pin portion in a state where the crankshaft is eccentrically held and rotationally driven around the central axis of the pin portion. In this apparatus, when the crankshaft is rotated at a low speed, it is balanced to some extent by the counterweight integrated with the chuck, so that it can be processed with high accuracy.

  In addition, recently, when the main shaft supporting the crankshaft is stopped at a predetermined angular position and the pin portion is rotated about the central axis, the steady rest device is positioned so as to be orthogonal to the pin portion and grinding is performed. It has been proposed (see, for example, Patent Document 1 below).

However, in any of the above methods, even if a smooth finished surface is obtained, a deviation in machining allowance due to grinding becomes a problem. In a recent crankshaft manufacturing process, a pin part may be processed by a pin mirror cutter in a process preceding a crankpin grinding process. This pin mirror cutter is provided with a large number of through-away tips in an annular shape, and the outer peripheral surface of the pin portion is cut while the cutter is disposed around the pin portion and rotated. Since this cutting process is not a high-precision process like a grinding process, when grinding later, the deviation of the grinding allowance of the pin part becomes large, and the balance center before grinding differs from the balance center after grinding. Sometimes. For this reason, when processing is performed by rotating the crankshaft at a high speed, the amount of unbalance increases, and processing cannot be performed with high accuracy.
JP-A-5-329756 (see paragraph number [0009], FIG. 1 and FIG. 6)

  The present invention has been made in order to solve the problems associated with the above-described prior art, and grinding a shaft-like workpiece provided with an eccentric member at a position eccentric with respect to the rotating shaft provides high accuracy and high smoothness. An object of the present invention is to provide a grinding apparatus and a grinding method capable of finishing a surface.

According to a first aspect of the present invention that achieves such an object, an outer peripheral surface of the eccentric member is rotated while rotating a shaft-like workpiece provided with an eccentric member at a position eccentric with respect to the rotation axis about the central axis of the eccentric member. A grinding apparatus for grinding with a grinding tool, wherein a pair of holding parts that eccentrically hold both ends of the shaft-like workpiece so that a central axis of the eccentric member is a center of rotation, and the holding part can be rotated. And at least two imbalance corrections that are provided inside the holding portion and coaxially with the rotation axis of the shaft-like workpiece and correct the unbalance of the shaft-like workpiece including the holding portion. A rotation balance correcting member comprising: a weight body for use; a second moving means for adjusting the phase of each of the weight bodies; and a first moving means for simultaneously adjusting the phases of the plurality of weight bodies; Detect vibration of means A vibration detector, a phase detector that detects a rotational position of said holding portion, the signal from the vibration detector and a signal from the phase detector is inputted, the position and size imbalance resulting from the two signals And a control device for obtaining a virtual balance weight provided at an opposite position obtained by adding 180 degrees to the phase angle of the position where the unbalance has occurred, and having a phase angle of 180 at the position where the unbalance has occurred. The virtual balance weight is distributed around the opposite position added, and the unbalance correction is performed by the second moving means and / or the first moving means so as to coincide with the rotation vector of the virtual balance weight. The weighting body is moved, and the unbalance of the axial workpiece including the holding portion is corrected during the rotation of the axial workpiece.

According to a second aspect of the present invention, a shaft-like workpiece having both ends held by the holding portion and provided with an eccentric member at a position eccentric with respect to the rotation shaft is rotated about the central axis of the eccentric member while the eccentric member is rotated. A grinding method in which a rough grinding with a large depth of cut is performed on a peripheral surface with a grinding tool, and then finish grinding with a small depth of cut is performed , wherein the holding portion is rotatably supported by a support means, and the grinding tool is In a state of being separated from the shaft-like workpiece, the center member rotates about the central axis of the eccentric member, calculates the position and size where the unbalance occurs, and sets the phase angle of the position where the unbalance occurs to 180 degrees. the center and the unbalance amount measuring step of determining a virtual balance weight, the opposite position where the unbalance is added 180 degrees phase angle position caused provided whenever added opposite position, the virtual balance weight The distribution, to match the vector during rotation of the virtual balance weight, said by the second moving means and / or the first moving means to move the weight body for the unbalance correction, axes including the holding portion An unbalance amount correcting step for correcting the unbalance of the workpiece in the course of rotation of the shaft workpiece, and after performing the correcting step, the rough grinding or the finish grinding is performed. Is the method.

According to the first and second inventions, the outer peripheral surface of the eccentric member is ground while rotating the shaft-like workpiece provided with the eccentric member at a position eccentric with respect to the rotation axis about the central axis of the eccentric member. If grinding by use tool, the holding center axis of the shaft-like workpieces the eccentric member by the holding unit such that the center of rotation, and further rotatably supported by the supporting means the holding portion, the grinding tool In a state of being separated from the shaft-like workpiece, the shaft member is rotated around the central axis of the eccentric member, the vibration of the support means and the rotational position of the holding portion are detected, and the shaft-like shape including the holding portion is detected. Calculate the position and size at which the unbalance of the workpiece has occurred, determine the virtual balance weight to be provided at the opposite position of the position where the unbalance has occurred, and add 180 degrees. 1 for phase angle The virtual balance weight is distributed around the opposite position added by 0 degrees, and the unbalance correction is performed by the second moving means and / or the first moving means so as to coincide with the rotation vector of the virtual balance weight. Since the weight of the machine is moved and the unbalance of the shaft-like workpiece is corrected during rotation, the shaft-like workpiece can be rotated at high speed while easily balancing the rotation. Can be finished to a highly smooth surface with high precision. In addition, a highly smooth finished surface can be obtained only by grinding without transferring the workpiece to a different processing facility.

  In particular, if the rotational balance is corrected during the rotation of the axial workpiece, the vibration of the axial workpiece during grinding can be suppressed, the axial workpiece can be rotated at high speed, and the axial workpiece can be rotated with high accuracy. Highly efficient grinding.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic sectional view of a crankshaft grinding apparatus according to an embodiment of the present invention.

Grinding apparatus 10 shown in FIG. 1, grinding the pin 3 (eccentric member) having a central axis R ₂ in a position eccentric to the rotation axis R ₁ of the journal portion 2 of the crankshaft 1 (axial workpiece) Is.

The grinding apparatus 10 generally includes a pair of holding portions 20, 21 where the center axis R ₂ of the pin 3 is held eccentrically at both ends of the crank shaft 1 so as to rotate around, the holding portions 20 and 21 A support means 11 that is rotatably supported; a rotation balance correction member 30 that corrects an unbalance of the crankshaft 1 including the holding portions 20 and 21; a vibration detector 40 that detects vibration of the support means 11; It has a phase detector 41 for detecting the phase of the support means 11 and grinds it with a grindstone (grinding tool) G while correcting the unbalance during rotation of the crankshaft 1.

  More specifically, the support means 11 is provided on a pair of spindle heads 13 and 14 provided on the base 12 and the spindle heads 13 and 14, and rotatably supports the holding portions 20 and 21. And a bearing 15.

  The pair of holding portions 20 and 21 are fixed to the main shafts 22 and 23 supported by the bearing 15 and inner end portions of the main shafts 22 and 23 and are eccentric with respect to the rotation axis of the main shafts 22 and 23. And chucks 24 and 25 having gripping portions 24a and 25a for holding the end portion of the crankshaft 1.

Each of the main shafts 22 and 23 is connected to a motor M ₁ that is synchronously controlled by a control device (not shown). When the motor M ₁ rotates, the main shafts 22 and 23 are connected to the chucks 24 and 25 via the main shafts 22 and 23, respectively. Then, the crankshaft 1 is rotated.

In the chucks 24 and 25 of the present embodiment, gripping portions 24a and 25a are provided at eccentric positions, the crankshaft 1 is held by the gripping portions 24a and 25a, and the pin shaft 3 rotates around the central axis R2. Grind with a grinding wheel G. That is, the crankshaft 1 held by the gripping portions 24a and 25a of the chucks 24 and 25 is mounted so that the center axis R2 of the pin portion 3 coincides with the rotation axes of the main shafts 22 and 23 by positioning means (not shown). And rotates about the central axis R2 of the pin portion 3.

  FIG. 2 is a schematic cross-sectional view showing the rotation balance correcting member and its periphery. The rotation balance correcting member 30 is provided inside each of the main shafts 22 and 23. Since both have the same configuration, the one on the main shaft 23 side will be described.

  As shown in FIG. 2, the rotation balance correction member 30 includes an unbalance correction weight body 31, a first correction member 30 </ b> A composed of first moving means 33 a that moves the weight body 31, and an unbalance correction. And a second correction member 30B composed of second moving means 33b for moving the weight body 32.

First modifying member 30A, the outer end of the cavity 34 formed inside each spindle 22, a motor M ₂ as a first moving means 33a is fixed, Ann rotary shaft of the motor M ₂ A cup-shaped member 31 a of a weight body 31 for correcting balance is attached, a flange portion 31 b is provided at the tip of the cup-shaped member 31 a, and the weight body 31 is rotated in the cavity 34.

The second correction member 30B has a motor M3 as second moving means 33b fixed to the inner end of the cup-shaped weight body 31, and a cylindrical member 32a is attached to the rotation shaft of the motor M3. A disk-shaped member 32b is provided at the tip of the columnar member 32a, and these are rotated in the weight body 31.

  However, for example, as shown in FIG. 4A, the weight body 31 of the first correction member 30A is provided with a columnar first weight 35 having a specific gravity larger than that of the base material at a part of the flange portion 31b. As shown in FIG. 4B, the weight body 32 of the second correction member 30B is provided with a columnar second weight 36 having a specific gravity larger than that of the base material on the disk-like member 32b. The weights 35 and 36 are not necessarily formed by providing a material having a specific gravity greater than that of the base material, but may be formed by an appropriate cutout portion or the like.

Thus, the rotation balance correcting member 30 is provided with the first correcting member 30A and the second correcting member 30B coaxially, and the second moving means 33b of the moving means 33 adjusts the phases of the weights 31 and 32 to each other. Since the first moving means 33a simultaneously adjusts the phases of the plurality of weight bodies 31, 32, the moving means 33, the weight bodies 31, 32, the main shafts 22, 23, the chucks 24, 25, and the crankshaft are adjusted. The balance correction of those including 1 is performed. Therefore, since the rotational balance is corrected by controlling the phases of the two weights 35 and 36 by the respective moving means 33, the configuration can be greatly simplified and the cost of the grinding apparatus can be reduced.

Further, the relationship between the static unbalance and the balancing weight body will be described with reference to the drawings. FIG. 3 is a schematic explanatory view showing the relationship between the static unbalance of the rotational balance correcting member and the counterweight. When the crankshaft 1 is rotated, it can be seen at which angular position the static unbalance amount occurs. For example, as shown in FIG. 3, it is assumed that an unbalance amount “W ₀ ” occurs at the position of the phase angle θ.

  In order to correct this unbalance, essentially, the same amount of weight “W” may be provided at a position opposite to the position where the unbalance occurs, that is, a position obtained by adding 180 degrees to the phase angle θ. However, since the unbalance amount differs for each crankshaft 1 to be processed, the unbalance amount cannot be corrected even if a single weight is provided.

For this reason, in the present embodiment, the known virtual balance weight “W” is divided into “W ₁ ” and “W ₂ ”, and each is divided around the installation position of the virtual balance weight to obtain a predetermined center angle θ. _{It is set to 1} . By dividing into two weights in this way and controlling the phase of each weight, it is possible to cope with the magnitude of static imbalance and the change in phase. In other words, if the combined vector created when each weight “W ₁ ” and “W ₂ ” is rotated coincides with that of the virtual balance weight “W”, the desired position can be obtained at a predetermined position only by performing simple geometric calculation. Thus, it is possible to correct the imbalance that occurs during rotation.

More specifically, first, the crankshaft 1 is rotated to determine at which angular position the static unbalance amount occurs by detecting the vibration of the support means 11 . That is , a vibration detector (hereinafter also referred to as a vibration sensor) 40 provided on the spindle heads 13 and 14 and a phase detector (hereinafter referred to as a rotation sensor ) provided on the spindles 22 and 23 may be referred to. ) The value detected by 41 is used. When the vibrations of the spindle heads 13 and 14 are measured, a static imbalance between the crankshaft 1 and the chucks 17 and 18, that is, vibration due to the rotation of the mass primary moment can be detected, and the amplitude thereof appears as an eccentric amount. Further, when the rotations of the main shafts 22 and 23 are measured, the phase angle that is decentered depending on the rotation position can be found. Therefore, if the signal from the vibration sensor 40 and the signal from the rotation sensor 41 are input to a control device (not shown) and calculated, the displacement amount and the displacement position can be detected, and the imbalance can be corrected accurately. The rotation balance can be improved.

  Next, the operation will be described.

First, the end of the crankshaft 1 is held by the chucks 24 and 25 , and grinding is performed with the center axis R2 of the pin 3 aligned with the rotation axes of the main shafts 22 and 23 by positioning means (not shown). The crankshaft 1 is rotated at the rotational speed of the hour.

<Unbalance measurement process>
During this rotation, the static unbalance amounts and phases of the crankshaft 1 and the chucks 24 and 25 are obtained by calculation processing based on detection signals from the vibration sensor 40 and the rotation sensor 41.

<Unbalance correction process>
When the magnitude of the static unbalance amount W ₀ and the phase angle θ are found by this calculation process, the rotation balance correction member 30 corrects the rotation balance. First, the motor M ₃ of the second correction member 30B is driven to adjust so that the first weight body 31 the phase of the second weight body 32 at a predetermined angle theta _1.

Then, the motor M ₂ of the first modification member 30A is driven, with the first weight member 31 and the second weight body 32 with a predetermined angle theta ₁ of the phase, the phase angle of the virtual balance weight W, theta + 180 Adjust to the degree. Incidentally, the magnitude and phase angle theta + 180 degrees virtual balance weight W, since known in advance, may drive the motor M ₃ and the motor M ₂ at the same time.

  As a result, the crankshaft 1 can reduce the unbalance amount before the next machining and rough grinding, can rotate the crankshaft 1 at the time of the rough grinding more rapidly, and can perform grinding efficiently. Can do.

<Machining and rough grinding process>
The pin portion 3 of the crankshaft 1 that rotates in this balanced state is subjected to machining by a pin mirror cutter and then rough grinding by a grindstone. Here, with rough grinding, the grinding allowance is large and the cutting depth D1 (see FIG. 5) is also large.

  However, the machining by this pin mirror cutter may be eccentric with respect to the center of the pin portion 3 as shown in FIG. 5, and the grinding allowance in the case of rough grinding may be non-uniform.

<Second unbalance measurement process>
Therefore, after the rough grinding process, the crankshaft 1 is rotated with the grindstone G separated from the crankshaft 1, and the crankshaft 1 and the chucks 24 and 25 are again rotated by the vibration sensor 40 and the rotation sensor 41 during this rotation. A vibration state and an eccentric position are detected, and a static unbalance amount and a phase are calculated and obtained.

<Second unbalance correction process>
When the magnitude of the static unbalance amount W ₀ and the phase angle θ are found by this calculation process, the rotation balance correction member 30 performs rotation balance correction in the same manner as in the unbalance correction step.

  As a result, the crankshaft 1 can reduce the unbalance amount before the next finish grinding process, can rotate the crankshaft 1 during the finish grinding process at higher speed, and can perform finish grinding with high efficiency. .

<Finishing grinding process>
Finish grinding, as shown in FIG. 6, the grinding allowance is small, but smaller depth of cut D ₂ of the wheel, the amount cutting per unit time by the grinding wheel is small. However, in this embodiment, since the unbalance amount of the crankshaft 1 is corrected, the pin portion 3 of the crankshaft 1 can be rotated at high speed, and even if the cutting amount per rotation of the workpiece is small, the grindstone Finish grinding can be performed under highly efficient conditions by increasing the peripheral speed. As a result, the generated grinding heat can be greatly suppressed, a highly smooth surface with few work-affected layers can be obtained with high efficiency, and the pin portion 3 can be processed with high accuracy.

  In the above embodiment, the machining process, the rough grinding process, the unbalance correction process, and the finish grinding process are performed after the attachment process and the unbalance correction process, but some processes may be omitted depending on the workpiece. Also good.

FIG. 7 is a schematic view showing a grinding cycle of the present embodiment. For example, after the crankshaft 1 is attached to the grinding apparatus 10, as shown in FIG. 7, the rough grinding process is immediately performed with the cutting amount D ₁ and the machining time t ₁ , and the unbalance measurement and correction process is performed for the time t ₂ . The finish grinding step may be performed with the cutting depth D ₂ and the processing time t ₃ .

In the case of the crankshaft 1 for a four-cylinder internal combustion engine, the rough shaft and the finish grinding are actually rotated at 500 rpm and the peripheral speed of the grindstone is about 200 m / sec.

According to the crankshaft grinding apparatus 10 of the embodiment described above, the pin portion 3 at both ends of the crank shaft 1 which is provided, pin 3 of the central axis R ₂ is holding portions 20, 21 and the support so that the center of rotation Since it is supported by the means 11 and the unbalance of the crankshaft 1 is corrected during rotation by the rotation balance correcting member 30 provided on the support means 11, the rotation balance can be easily achieved. Can be rotated at a high speed to achieve a highly smooth surface.

  In particular, if the rotation balance is corrected while the crankshaft 1 is rotating, vibration of the crankshaft 1 during grinding can be suppressed and the crankshaft 1 can be rotated at high speed, so that the crankshaft 1 can be made highly accurate and highly efficient. Can be ground. As a result, the equipment does not change every time machining is changed as in the past, and a highly smooth finished surface can be obtained only by grinding, and there is no need to transfer the workpiece to a different machining equipment. This is advantageous in terms of cost.

The rotation balance correcting member 30 includes at least two weight bodies 31 and 32 that rotate about the central axis R ₂ of the pin portion 3, and controls the phase of the weight bodies 31 and 32 to thereby reduce the static unbalance. Can cope with changes in balance and phase.

  The moving means 33 of the rotation balance correcting member 30 is provided with one weight body 31 and first moving means 33a for adjusting the phase of the weight body 31 in the main shafts 22 and 23 of the grinding apparatus. Since the other weight body 32 and the second moving means 33b for adjusting the phase of the other weight body 32 are provided in 31, a simple rotation balance correcting means can be provided, and the grinding apparatus can be manufactured at low cost. Can be produced.

  If the rotation balance correcting member 30, the vibration sensor 40, and the rotation sensor 41 are respectively provided at both ends where the shaft-like workpiece is supported, the displacement is corrected from both the left and right sides, so that the unbalance can be more accurately performed. Can be corrected and the rotation balance can be improved.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. For example, in the above-described embodiment, the displacement amount and the displacement position in the pin portion of the crankshaft are detected. However, the present invention is not limited to this. The present invention can also be widely applied to a shaft-shaped workpiece provided with.

  Moreover, although the rotation sensor 41 is provided in the chuck | zipper part 24, as long as it can detect the position of a rotation part, it may be provided anywhere.

  The grinding apparatus and the grinding method according to the present invention can smoothly grind an axial workpiece provided with an eccentric member and can obtain a desired accuracy in a short time, such as a crankshaft or a camshaft of an automobile engine. Suitable for grinding.

It is a schematic structure figure showing a crankshaft grinding device concerning an embodiment of the present invention. It is a schematic sectional drawing which shows a rotation balance correction member etc. It is a schematic explanatory drawing which shows the relationship between the static imbalance of a rotation balance correction member, and a balance weight body. (A) (B) is sectional drawing which shows the rotation balance correction member of this embodiment. It is explanatory drawing which shows the state at the time of rough grinding. It is explanatory drawing which shows the state at the time of finish grinding. It is the schematic which shows the grinding process cycle of this embodiment.

Explanation of symbols

1 ... Crankshaft (axial workpiece),
3 ... Pin part (eccentric member),
11: Support means,
20, 21 ... holding part,
30 ... Rotation balance correction member,
31, 32 ... weights,
33 ... moving means,
33a ... 1st moving means,
33b ... second moving means,
35, 36 ... Weight,
40: Vibration detector,
41 ... Phase detector,
G ... Whetstone (grinding tool),
R ₁ ... the rotation axis of the crankshaft,
R ₂ ... The central axis of the pin part.

Claims (3)

A grinding apparatus that grinds the outer peripheral surface of an eccentric member with a grinding tool while rotating an axial workpiece provided with an eccentric member at a position eccentric with respect to the rotation axis, around the central axis of the eccentric member. And
A pair of holding portions that eccentrically hold both ends of the shaft-like workpiece so that the center axis of the eccentric member is a rotation center;
A support means for rotatably supporting the holding portion;
At least two unbalance correction weight bodies that are provided in the holding portion and coaxially with the rotation axis of the axial workpiece and correct the unbalance of the axial workpiece including the holding portion, A rotation balance correcting member comprising: second moving means for adjusting the phases of the weight bodies; and first moving means for simultaneously adjusting the phases of the plurality of weight bodies ;
A vibration detector for detecting vibration of the support means;
A phase detector for detecting the rotational position of the holding unit;
The signal from the vibration detector and the signal from the phase detector are input, and the position and magnitude at which the unbalance occurs are calculated from both signals, and the phase angle at the position at which the unbalance occurs is 180 degrees. And a control device for obtaining a virtual balance weight provided at the opposite position added ,
The virtual balance weight is distributed around the opposite position obtained by adding 180 degrees to the phase angle of the position where the unbalance has occurred, and the second moving means and / Alternatively , the grinding apparatus is characterized in that the unbalance correcting weight body is moved by the first moving means to correct the unbalance of the shaft-like workpiece including the holding portion during the rotation of the shaft-like workpiece.   The grinding apparatus according to claim 1, wherein the rotation balance correcting member, the vibration detector, and the phase detector are provided at both ends where the shaft-like workpiece is supported. A tool for grinding the outer peripheral surface of the eccentric member while rotating about the central axis of the eccentric member, with the shaft-like workpiece provided with the eccentric member at the position where both ends are held by the holding portion and eccentric with respect to the rotation axis Is a grinding method for performing rough grinding with a small depth of cut after rough grinding with a large depth of cut ,
The holding portion is rotatably supported by a supporting means, and the grinding tool is rotated around the central axis of the eccentric member in a state where the grinding tool is separated from the shaft-shaped workpiece, An unbalance amount measuring step for calculating a magnitude and obtaining a virtual balance weight provided at an opposite position obtained by adding 180 degrees to the phase angle of the position where the unbalance has occurred ;
The virtual balance weight is distributed around the opposite position obtained by adding 180 degrees to the phase angle of the position where the unbalance has occurred, and the second moving means and / or move the weight body for the unbalance correction by the first moving means, and a unbalance amount correction step for correcting during the rotation of the shaft-like workpieces imbalance axial workpieces including the holding portion Have
A grinding method comprising performing the rough grinding or finish grinding after performing the correction step .

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