JP4296291B2 - Cylindrical grinding method and cylindrical grinding machine - Google Patents

Description

  The present invention relates to a cylindrical grinding method and a cylindrical grinding machine for grinding a workpiece to a predetermined diameter, and more specifically, detecting that a defective portion or a protrusion has occurred in a ground portion during grinding, and the defect The present invention relates to a technique for correcting parts.

For example, by cutting while rotating a rotating grindstone at a predetermined feed speed with respect to a rotating workpiece, in the cylindrical grinding process to grind the workpiece to a predetermined diameter, the workpiece processing accuracy during grinding is measured, As a system for feeding back the measured data, an outer diameter measuring device using an in-process gauge is generally used (for example, see Patent Documents 1 and 2).
Japanese Patent Laid-Open No. 2002-239876 (pages 3 to 5, FIGS. 1 and 5) JP 2003-094293 A (page 3 and page 4, FIG. 1 and FIG. 2)

  However, an outside diameter measuring device using an in-process gauge only measures the outside diameter dimension, ellipse accuracy, roundness, etc. of the workpiece, so it is not possible to detect defects or protrusions that occur during machining. Is possible.

  For this reason, for example, when the pin part of a crank used in an automobile engine is subjected to cylindrical grinding, the elastic deformation of the rotating grindstone and the work is released due to a certain factor, and the work can be scraped at a stroke, so that a defective part or a protrusion is formed on a part of the work. In such a case, the detection of such a defective portion is limited to either the visual inspection by the contact measurement after the workpiece machining or the measurement by the outer shape roundness measuring instrument.

  In particular, grinding the pin part of the crank supports the part of the crank with a work support member (work rest) until the fine feed of the finish is completed in order to increase the roundness of the pin part. Once a defective part is generated by feeding, the defective part is struck one after another, and it is impossible to correct it.

  Therefore, the present invention provides a cylindrical grinding method and a cylindrical grinding machine that can detect a defective portion or a protruding portion during machining of a workpiece and correct the defective portion or protruding portion to perform cylindrical grinding with high processing accuracy. The purpose is to provide.

The present invention supports a workpiece by contacting a workpiece support member that can be moved forward and backward to a grinding portion of the rotating workpiece, cutting the workpiece while feeding a rotating grindstone to the workpiece at a predetermined feed speed, and grinding the workpiece. This is a cylindrical grinding method in which a diameter detection member is brought into contact with a portion and the workpiece is ground to a predetermined diameter while measuring the diameter of the ground portion. In the cylindrical grinding method of the present invention, when a defect portion or projection generated during grinding of a workpiece by a rotating grindstone is detected, the workpiece support member is retracted from the workpiece, and then the defect portion or projection is removed by the rotating grindstone. Correct grinding.

According to the cylindrical grinding method of the present invention, when a chipped portion or a projection generated during grinding of a workpiece by a rotating grindstone is detected, the workpiece support member is retracted from the workpiece, and then the chipped portion or the projection is rotated by the rotating grindstone. Since the work support member is in a position retracted from the work, the work is not pushed toward the rotating grindstone by the work support member, and the work is pushed toward the work supporting member by the rotating grindstone. There is nothing. Therefore, the generated defect or projection is scraped by the rotating grindstone, so that cylindrical processing with high roundness can be realized, and the processing yield can be greatly improved.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

[Configuration of cylindrical grinding machine]
FIG. 1 is a perspective view showing the overall configuration of a cylindrical grinder, FIG. 2 is a control block diagram of the cylindrical grinder, and FIG. 3 is a plan view showing an example of a crankshaft.

  As shown in FIGS. 1 and 2, the cylindrical grinding machine according to the present embodiment makes contact with a work rotating means for clamping and rotating the work 1 and a work rest 2 which is a work supporting member that can be moved forward and backward. A workpiece support means for supporting the workpiece 1; a grinding feed means for grinding the workpiece 1 to have a predetermined diameter by cutting the rotating grindstone 3 while feeding the rotating grindstone 3 at a predetermined feed speed; Diameter measuring means for measuring the diameter of the grinding part by contacting an in-process gauge arm 4 which is a diameter detecting member in contact with the grinding part of the work 1, and a missing part or a protrusion generated during grinding of the work 1 by the rotating grindstone 3 A non-cylindrical part detecting means for detecting the workpiece, and the work rest 2 is retracted from the work 1 when the non-cylindrical part detecting means detects a missing part or a protruding part on the work 1. And a control unit 5 which is a control means for instructing the lifting means.

  For example, as shown in FIG. 3, a crankshaft used for an automobile engine is used for the work 1. The grinding parts processed by the cylindrical grinder of the present embodiment are the crankshaft pin portions 6a, 6b, 6c and 6d to which the pistons are attached. The workpiece 1 is fed by a predetermined amount by a movable table 16 which is slidable in the direction indicated by an arrow D in FIG.

  As shown in FIG. 1, the work rotation means includes a first work rotation drive unit 7 and a second work rotation drive unit 8 provided on both sides of the work 1. The first workpiece rotation driving unit 7 and the second workpiece rotation driving unit 8 are each composed of a workpiece clamp (work chuck) 9 and 10 for clamping the end portions 1a and 1b of the workpiece 1 and a workpiece rotation driving motor 11, respectively. And a rotary drive shaft 12 that rotates. The rotation drive shaft 12 is provided between the first workpiece rotation driving unit 7 and the second workpiece rotation driving unit 8, and the workpiece clamps 9 and 10 are rotated in synchronism with each other to rotate the workpiece. Rotate 1

  As shown in FIGS. 1 and 2, the work support means includes a work rest 2 that supports the rotating grindstone 3 from the opposite side opposite to the rotating grindstone 3, and the workrest 2 can be moved forward and backward with respect to the work 1. And a work rest drive unit (not shown). The workrest 2 is movable between a forward movement position (a solid line position in FIG. 2) that supports the work 1 and a backward movement (retraction) position (a two-dot chain line position in FIG. 2) away from the work 1.

  The grinding process feeding means includes a rotating grindstone feeding mechanism 13 that feeds the rotating grindstone 3 to the rotating workpiece 1 at a predetermined feeding speed. As shown in FIG. 2, the rotary grindstone feed mechanism unit 13 moves the rotary grindstone 3 attached to the grindstone base 18 with respect to the workpiece 1 by a ball screw 20 that is rotated by driving a grindstone feed servomotor 19. It is possible to move in the direction of approaching and separating (direction C). Further, the feed speed of the rotary grindstone 3 by the rotary grindstone feed mechanism 13 can be freely adjusted by the grindstone feed servomotor 19 and can be set to an arbitrary speed.

  As shown in FIG. 1, the rotating grindstone 3 transmits the rotation of the grindstone driving motor 14 to a pulley belt (not shown) housed in the belt cover 15, and this pulley belt causes the arrow B in FIG. It is comprised so that it may rotate in the direction shown by.

  As shown in FIG. 2, the diameter measuring means includes an implos gauge 17 having a pair of in-process gauge arms 4. The implos gauge 17 measures the diameter of the ground portion by bringing the pair of in-process gauge arms 4 into contact with the ground portion of the workpiece 1.

  The non-cylindrical portion detecting means detects a missing portion or a protruding portion generated during grinding of the workpiece 1 by the rotating grindstone 3. As shown in FIG. 2, the non-cylindrical portion detection means includes an in-process gauge amplifier 21 that amplifies the amplitude of the in-process gauge arm 4 and a threshold value detection unit that converts the amplitude and detects a predetermined amplitude threshold value. 22. The threshold value is determined based on whether or not the roundness of the pin portion 6a is within a range in which the product can be satisfied among the amplitudes of the swing of the in-process gauge arm 4 during the cutting of the pin portion 6a. That is, the upper and lower limit values of the amplitude value by the in-process gauge arm 4 that is allowed to the maximum when the roundness of the pin portion 6a is satisfactory can be used as the threshold value.

  As shown in FIG. 2, when the threshold detection unit 22 detects that the threshold has been exceeded, the control unit 5 issues a command to the workrest drive unit so as to retract the workrest 2 from the workpiece 1. When the threshold detection unit 22 detects that the threshold has been exceeded, it can be determined that a defective portion (notch) or a protrusion has been formed in the ground portion during grinding for some reason.

[Cylindrical grinding method]
Next, a method for grinding the pin portion 6a of the crankshaft using the above-described cylindrical grinder will be described.

  FIG. 4 is a flowchart sequentially showing the steps of cylindrical grinding of the pin portion according to the method of the present invention, FIG. 5 is a diagram showing the relationship between grinding wheel cutting, in-process gauge diameter data and in-process gauge amplitude and time, and FIG. FIG. 7 is a diagram when a projection is generated due to the formation of the defect, FIG. 8 is a diagram when a defect is further generated by the projection, and FIG. 9 is a diagram showing the work rest. It is a figure when retracting and correcting and grinding a defective part and a projection part.

  First, the flowchart of FIG. 4 is started by driving the grindstone driving motor 14 to rotate the rotating grindstone 3. Next, in step S1, the workpiece 1 which is a crankshaft is put into a cylindrical grinder. Next, in step S2, both ends 1a and 1b of the workpiece 1 are clamped by the workpiece clamps 9 and 10, and the workpiece 1 is fixed.

  Next, in the step S3, the work 1 is rotated by rotating the work rotation drive motor 11. Next, in the step S4, the work rest 2 is advanced with respect to the work 1, and the work rest 2 is brought into contact with the pin portion 6a as shown in FIG. The workrest 2 abuts so as to support the pin portion 6 a from the side opposite to the rotating grindstone 3. By the contact of the work rest 2 with the work 1, it is possible to suppress the rotational shake of the rotating work 1.

  Next, in the step S5, the grindstone feeding servo motor 19 is driven to advance the rotating grindstone 3 in the direction approaching the workpiece 1. And the 1st feed process which grinds the pin part 6a of the workpiece | work 1 is performed, sending this rotary grindstone 3 with a predetermined feed speed (fast feed). In the first feed, as shown in FIG. 5A, the feed speed of the rotating grindstone 3 is increased to rough the pin portion 6a.

  Next, in step S6, the in-process gauge 17 is driven to bring the in-process gauge arm 4 into contact with the pin portion 6a as shown in FIG. In the step S7, the diameter of the ground portion of the pin portion 6a by the rotating grindstone 3 is measured by the in-process gauge 17. Next, when it is detected by the in-process gauge 17 that the diameter has been set in the first feed machining, the flowchart of FIG. 4 is advanced to the step S8.

  In the step S8, as shown in FIG. 5A, the second feed machining is performed in which the machining is performed at a feed speed (medium feed) in which the feed speed of the rotating grindstone 3 is delayed from the first feed. In the second feed machining, the diameter of the ground portion of the pin portion 6a by the rotating grindstone 3 is similarly measured by the in-process gauge 17. Then, if it is detected by the in-process gauge 17 that the diameter has been set in the second feed machining, the flowchart of FIG. 4 is advanced to the step S9.

  In the process of step S9, as shown in FIG. 5A, the third feed processing is performed in which processing is performed at a speed (microfeed) in which the feed speed of the rotating grindstone 3 is further delayed than the medium feed. In the third feed machining, the diameter of the grinding portion of the pin portion 6a by the rotating grindstone 3 is also measured by the in-process gauge 17.

  In the next step S10, a missing circle detection mode is entered in which it is detected whether or not a chipped portion or a protruding portion in which a notch is formed in the ground portion of the pin portion 6a is formed. In this missing circle detection mode, a threshold is set for the raw data of the amplitude at which the in-process gauge arm 4 vibrates before being converted into diameter data by the in-process gauge 17 (see FIG. 5B) (FIG. 5C The amplitude of the in-process gauge arm 4 is monitored.

  For example, as shown in FIG. 6, if a defect 24 is generated in the pin 6 a, the amplitude exceeding the threshold when the defect 24 passes through the in-process gauge arm 4 has the above-described threshold detection unit 22. Detected. When the amplitude exceeding this threshold is detected, it is determined that the defective portion 24 is formed in the ground portion. In addition, the depth L of the defect | deletion part 24 is about 3-5 micrometers, for example. Moreover, when this defect | deletion part 24 passes the workrest 2, the whole workpiece | work 1 is pushed to the workrest 2 side like the state shown with a continuous line from the state shown with the dashed-two dotted line of FIG. For this reason, as shown in FIG. 7, the projection part 23 is formed in the grinding part of the pin part 6a.

  Moreover, when this protrusion part 23 passes the work rest 2, the workpiece | work 1 is pushed to the rotating grindstone 3 side as shown with a continuous line from the state shown with the dashed-two dotted line of FIG. As a result, a new defect portion 24 is generated in the ground portion of the pin portion 6a as shown in FIG. The chain due to the formation of the protrusion 23 and the generation of the defect 24 occurs until the microfeed is completed. For example, at the time of the third feed processing by microfeed, when the margin for grinding is 10 μm, the feed is 3 μm / second, and the work rotation speed is about 60 to 100 rpm / minute, two defect portions 24 and one protrusion 23 are provided. I can do it.

  In step S11, it is determined whether or not the amplitude value detected by the threshold detector 22 is within the set threshold range. If the detected amplitude value is within the threshold range in this determination step, the step of FIG. 4 is advanced to the next step S12. In the process of step S12, the pin portion 6a is ground by the rotating grindstone 3 (microdwell) with the feed of the rotating grindstone 3 stopped (final grinding process) in which grinding is performed until a predetermined diameter is obtained. A fourth feed machining is performed.

  In the fourth feed machining, when the pin portion 6a is finished to a predetermined set diameter, the work rest 2 is moved backward in the step S13. Next, in step S <b> 14, the in-process gauge arm 4 is retracted from the work 1. This completes the processing of the pin portion 6a. When grinding of the first pin portion 6a is completed, the movable table 16 is moved to feed the workpiece 1, and the pin portion 6b to be processed next is moved to the grinding position.

  On the other hand, in the step S11, when the amplitude value detected by the threshold detection unit 22 exceeds the set threshold range, the flowchart of FIG. 4 is shifted to the step S15. In the step S15, the work rest 2 is retracted (retracted) in a direction away from the work 1. At this point, the pin portion 6a has already been formed with the defect 24 or the protrusion 23, but the generation of a new defect 24 or protrusion 23 can be suppressed.

  Next, the flowchart of FIG. 4 is advanced to the step S16. In step S16, for example, a fifth feed process is performed in which the rotary grindstone 3 is processed at a grindstone feed speed (second microfeed) that is slower than the microfeed. In the fifth feed machining, since the work rest 2 is in a position retracted from the work 1, the work 1 is not pushed by the work rest 2 toward the rotating grindstone 3, and the work 1 is moved by the rotating grindstone 3. It is not pushed to the side. Accordingly, the generated defect 24 or protrusion 23 is scraped by the rotating grindstone 3 as indicated by a two-dot chain line in FIG.

  After finishing the fifth feed processing by the second microfeed, the flowchart of FIG. 4 is advanced to the step S17. In the process of step S17, fourth feed machining by microdwell is performed. When the diameter of the pin portion 6a reaches a predetermined value, the in-process gauge arm 4 is retracted from the work 1 in the next step S18. Thus, it is possible to process the highly accurate pin portion 6a having no round portion 24 or the protruding portion 23 and having a high roundness, and the flowchart of FIG. 4 ends.

[Effects of this embodiment]
According to the present embodiment, in the final grinding process of finishing the workpiece 1 to a predetermined diameter, the workpiece 1 is retracted from the workpiece 1 and the workpiece 1 is ground. Since it is not pressed and urged to the rest 2 side, it can prevent that the defect | deletion part 24 or the projection part 23 is formed in a grinding part.

  Moreover, according to this Embodiment, when the defect | deletion part 24 or the protrusion part 23 which arose during grinding of the workpiece | work 1 by the rotating grindstone 3 is detected, since the workpiece rest 2 is evacuated from the workpiece | work 1, the further defect | deletion part 24 is provided. Or generation | occurrence | production of the projection part 23 can be prevented.

  Further, according to the present embodiment, the work rest 2 is retracted from the work 1 and at the same time, the feed speed of the rotating grindstone 3 is made slower than the feed speed before the defect portion 24 or the protrusion 23 is detected. The generated defect 24 or protrusion 23 can be ground and corrected.

  Further, according to the present embodiment, a threshold value is set for the amplitude value by the in-process gauge arm 4, and when the threshold value is exceeded, the defect portion 24 or the protrusion portion 23 generated during grinding of the workpiece 1 is assumed. Since it determines, the defect | deletion part 24 or the protrusion part 23 can be detected without visual observation also in workpiece | work processing.

[Other Embodiments]
Although specific embodiments to which the present invention is applied have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  For example, in the above-described embodiment, the work rest 2 is retracted from the work 1 and at the same time, the feed speed of the rotating grindstone 3 is slower than the feed speed before detecting the missing part 24 or the protrusion part 23. Even if it does, the same effect is acquired.

It is a perspective view which shows the whole structure of a cylindrical grinding machine. It is a control block diagram of a cylindrical grinding machine. It is a top view which shows an example of a crankshaft. It is a flowchart which shows sequentially the process of cylindrically grinding a pin part by the method of this invention. It is a figure which shows the relationship between grinding wheel cutting, in-process gauge diameter data, an in-process gauge amplitude, and time, respectively. It is a figure when the defect | deletion part arises in the grinding part. It is a figure when a projection part arises because a defective part is made. It is a figure when the defect | deletion part has arisen further by the projection part. It is a figure at the time of retracting a work rest and carrying out correction grinding of a defective part and a projection part.

Explanation of symbols

1 ... Work (workpiece)
2. Work rest (work support member)
DESCRIPTION OF SYMBOLS 3 ... Rotary grindstone 4 ... In-process gauge arm 5 ... Control part (control means)
6a-6d ... Pin part (grinding part)
7 ... 1st work rotation drive part (work rotation means)
8 ... 2nd work rotation drive part (work rotation means)
13 ... Rotary whetstone feed mechanism (grinding feed means)
21 ... In-process gauge amplifier (non-cylindrical part detection means)
22: Threshold detection unit (non-cylindrical part detection means)
23 ... Projection 24 ... Defect

Claims (5)

A workpiece support member that can be moved forward and backward is brought into contact with the grinding portion of the rotating workpiece to support the workpiece. A cylindrical grinding method in which the workpiece is ground to a predetermined diameter while contacting a member and measuring the diameter of the ground portion,
When detecting a chipped portion or a projection generated during grinding of the workpiece by the rotating grindstone, the workpiece supporting member is retracted from the workpiece , and thereafter the chipped portion or the protruding portion is corrected and ground by the rotating grindstone. A cylindrical grinding method characterized. The cylindrical grinding method according to claim 1 ,
A cylindrical grinding method, wherein the workpiece support member is retracted from the workpiece, and at the same time, the feed speed of the rotating grindstone is made slower or faster than the feed speed before detecting the chipped portion or the protrusion. The cylindrical grinding method according to claim 1 or 2 ,
A threshold value is set for the amplitude value that vibrates when the diameter detection member comes into contact with the grinding part, and when the threshold value is exceeded, it is determined that the defect or protrusion is generated during grinding of the workpiece. A cylindrical grinding method characterized by the above. A workpiece rotating means for clamping and rotating the workpiece;
A workpiece support means for supporting the workpiece by abutting a workpiece support member which is movable back and forth on the grinding portion of the workpiece rotated by the workpiece rotation means;
A grinding feed means for grinding the workpiece so as to have a predetermined diameter by cutting the rotary grindstone while feeding the rotary grindstone at a predetermined feed speed;
A diameter measuring means for measuring a diameter of the ground portion by contacting a diameter detecting member to the ground portion of the workpiece;
A non-cylindrical part detecting means for detecting a missing part or a protruding part generated during grinding of the workpiece by the rotating grindstone;
Control means for instructing the work support means to retract the work support member from the work when a non-cylindrical part detection means detects a missing part or a protrusion on the work ,
When a missing portion or a projection generated during grinding of the workpiece by the rotating grindstone is detected, the workpiece support member is retracted from the workpiece, and then the missing portion or the projection is corrected and ground by the rotating grindstone. Cylindrical grinding machine. A cylindrical grinder according to claim 4 ,
The control means retracts the workpiece support member from the workpiece, and at the same time, grinds so that the feed speed of the rotating grindstone is slower or faster than the speed before detecting the chipped portion or the protruding portion. A cylindrical grinder characterized by instructing a feeding means.

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