JP3766764B2 - Dressing method and apparatus for grinding wheel for valve stem - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a grinding wheel dressing method and apparatus for grinding a shaft portion of a valve stem used in an engine such as an automobile.
[0002]
[Prior art]
A valve stem used for an engine is formed, for example, by joining an umbrella portion forged using a heat-resistant alloy and a shaft portion made of ordinary steel by a friction welding method. This valve stem is subjected to heat treatment after removing burrs and the like, and the shaft portion is subjected to three-step grinding consisting of rough grinding, central research, and fine grinding, or two-step grinding consisting of rough grinding and fine grinding.
[0003]
A grinding wheel used for such a grinding process becomes clogged and worn out when the grinding process is repeatedly performed. Therefore, it is necessary to perform dressing with a dresser and perform shaping and reshaping.
[0004]
In this case, conventionally, after grinding a predetermined number (for example, 30 to 40) of valve stem shafts with a grinding wheel, the grinding process is temporarily stopped and the grinding wheel is dressed for a time. Dressing is made by the amount of cut y over x, and the shaft portion is ground again. The dressing time x and the depth of cut y vary depending on conditions. For example, x is 30 seconds and y is 20 μm.
[0005]
[Problems to be solved by the invention]
However, this method has a drawback that the production efficiency of the valve stem is reduced because the grinding process is stopped and the dressing is performed.
[0006]
Therefore, a method of performing dressing while grinding with a grinding wheel has been proposed (see, for example, “grinding method” disclosed in JP-A-8-108364).
[0007]
However, in this method, when dressing with a dresser having a width equal to or greater than that of the grinding wheel, the hardness differs depending on the material of the umbrella portion and the shaft portion of the valve stem. There is a concern that irregularities occur on the surface of the grinding wheel and the irregularities are transferred to the dresser that dresses the grinding wheel. Then, the unevenness of the grinding wheel cannot be removed with the dresser having the unevenness, and if the grinding wheel with the unevenness is used, the processing accuracy of the valve stem is lowered.
[0008]
On the other hand, if a dresser with a narrow width is used for the grinding wheel and dressing is performed while displacing in the width direction of the grinding wheel, a step is formed in the grinding wheel during dressing, and this step is the valve stem. There is a concern that the processing accuracy of the valve stem is lowered.
[0009]
In addition, hard grindstone generated by dressing is caught in the rotation of the grinding wheel and the surface of the valve stem is damaged, or the adjustment wheel made of hard rubber that presses the valve stem against the grinding wheel is damaged. There is a drawback that the service life of the adjusting vehicle is shortened.
[0010]
The present invention has been made to solve the above-mentioned problems, and it is possible to improve the production efficiency of the valve stem and improve the processing accuracy, and there is no concern that the surface of the valve stem or the adjustment vehicle is damaged. An object of the present invention is to provide a dressing method and apparatus for a grinding wheel for valve stem.
[0011]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention is a method of dressing a dressing wheel against a grinding wheel for grinding a shaft portion of a valve stem,
The amount of cut of the dresser is set so that the shaft portion of the valve stem that has been ground has a predetermined processing accuracy,
The number of shaft portions of the valve stem to be ground while dressing the grinding wheel once is divided by the time required to grind one shaft portion of the valve stem from the time required for one dressing. Is set so that the amount of wear of the grinding wheel is smaller than the depth of cut,
The dresser feed speed is set to a speed at which the surface roughness of the finished surface of the dressed grinding wheel is finished until a predetermined number of shaft portions of the valve stem can be ground .
The dressing is performed while sucking the grindstone particles generated during the dressing .
[0012]
According to the present invention, since the grinding wheel is dressed while grinding the shaft portion of the valve stem, it is not necessary to stop the grinding process at the time of dressing, and the production efficiency is improved.
[0013]
In this case, the depth of cut is 1 to 7 μm, the number of valve stems to be ground while dressing the grinding wheel once is 5 to 10, and the feed rate of the dresser is 0.1 to 0.5 mm / When set to rev, a valve stem with good machining accuracy can be obtained, which is preferable.
[0014]
Further, it is preferable to perform dressing while sucking the grindstone particles generated during the dressing because the grindstone particles prevent the valve stem and the adjustment wheel from being damaged.
[0015]
Furthermore, in the dressing step, when dressing is performed by displacing the dresser formed narrower than the grinding wheel in the axial direction in a state where the dresser is cut into the grinding wheel, unevenness is generated in the dresser. This can be prevented, and this unevenness is preferably not transferred to the grinding wheel.
[0016]
In addition, the present invention is formed in a substantially cylindrical shape, a grinding wheel that performs grinding by contacting the shaft portion of the valve stem while rotating,
A dresser that is formed in a substantially disc shape, cut into the grinding wheel while rotating and displaced in the axial direction thereof to dress the grinding wheel;
A suction mechanism for sucking the grinding stone particles generated when dressing the grinding wheel;
It is characterized by providing.
[0017]
According to the present invention, since the grinding wheel is dressed by the dresser while the shaft portion of the valve stem is ground by the grinding wheel, it is not necessary to stop the grinding process. Moreover, since the grindstone generated by dressing is sucked by the suction mechanism, the concern that the surface of the valve stem or the adjusting wheel is damaged by the grindstone can be eliminated.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The dressing method for a grinding wheel for valve stem according to the present invention will be described in detail below with reference to the accompanying drawings by giving a preferred embodiment in relation to an apparatus for carrying out the dressing method.
[0019]
In FIG. 1, reference numeral 10 indicates a dressing apparatus according to the present embodiment.
[0020]
The dressing device 10 includes a grinding wheel 12 formed in a substantially cylindrical shape, and the grinding wheel 12 rotates about its axis. The dressing device 10 is provided with an adjustment wheel 18 made of hard rubber in parallel with the grinding wheel 12, and the adjustment wheel 18 acts to apply a rotational force to the shaft portion 16 of the valve stem 14 that is a workpiece.
[0021]
A dresser 20 that is formed in a narrow disk shape and can come into contact with the grinding wheel 12 is provided above the grinding wheel 12. The dresser 20 can be displaced in the axial direction as shown by an arrow under the action of an actuator (not shown).
[0022]
In the vicinity of the dresser 20, a suction nozzle (suction mechanism) 22 formed in a length along the width direction of the grinding wheel 12 is disposed. The suction nozzle 22 is not shown in the drawing via a conduit 24. Connected to the source. The suction nozzle 22 has an opening (not shown) that opens to face the grinding wheel 12 and the dresser 20.
[0023]
A grinding coolant discharge nozzle 26 is disposed in the vicinity of the suction nozzle 22 in parallel with the suction nozzle 22, and the grinding coolant discharge nozzle 26 is connected to a grinding coolant supply source (not shown) via a conduit 28. Connected to. The grinding coolant discharge nozzle 26 has an opening (not shown) that opens toward the grinding wheel 12.
[0024]
Support members 30a and 30b are provided in the vicinity of the suction nozzle 22 so as to be able to approach and separate from the grinding wheel 12, and these support members 30a and 30b can be moved forward and backward with respect to the grinding wheel 12 by a linear actuator (not shown). . The support members 30 a and 30 b support the shaft portion 16 of the valve stem 14.
[0025]
The dressing apparatus 10 has a pair of plate-like members 36a and 36b formed in a substantially L shape, and a cylinder 38 is provided between the plate-like members 36a and 36b. The cylinder rod 40 of the cylinder 38 is provided with a pressing member 42 that can be displaced between the plate-like members 36a and 36b. Holes 43a and 43b having an oval cross section are defined in the pressing member 42 in parallel with each other, and rod members 45a and 45b bridged between the plate-like members 36a and 36b are inserted into the holes 43a and 43b. Therefore, the displacement range of the pressing member 42 with respect to the plate-like members 36a and 36b is restricted. The plate-like members 36 a and 36 b, the cylinder 38, and the pressing member 42 can be integrally displaced in the circumferential direction of the grinding wheel 12. An umbrella portion 48 of the valve stem 14 is fitted into a separation portion formed between the bent end portions of the plate-like members 36 a and 36 b, and the one end portion 46 of the pressing member 42 presses the umbrella portion 48 to press the umbrella. The portion 48 is sandwiched between the plate-like members 36 a and 36 b and the pressing member 42.
[0026]
The dressing apparatus 10 includes a cylinder 50, and the cylinder rod 52 of the cylinder 50 serves to displace the valve stem 14 disposed between the grinding wheel 12 and the adjusting wheel 18 in the axial direction thereof. The dressing apparatus 10 is provided with a passage 54, and the valve stem 14 is conveyed to the passage 54. A passage confirmation detection plate 56 is provided above the passage 54 so as to be rotatable in the direction of the arrow, and the rotational movement of the passage confirmation detection plate 56 is detected by a rotation detection sensor 58 (see FIG. 1).
[0027]
The dressing apparatus 10 according to the present embodiment is basically configured as described above. Next, regarding the method of using the dressing apparatus 10, the valve stem 14 according to the present embodiment is ground. The relationship with the dressing method of the grindstone 12 will be described with reference to the flowchart shown in FIG.
[0028]
The grinding wheel 12 is, for example, 1400 rpm, while the adjusting wheel 18 is rotating in the same direction, for example, at 20 rpm. Further, a vacuum suction source (not shown) connected to the suction nozzle 22 is driven, and the grindstone generated from the grinding wheel 12 during the grinding is sucked from the suction nozzle 22. Further, the grinding coolant is discharged from the grinding coolant discharge nozzle 26 under the driving action of a grinding coolant supply source (not shown).
[0029]
Furthermore, the valve stem 14 is conveyed to the dressing device 10, the shaft portion 16 is supported by the support members 30 a and 30 b, and the umbrella portion 48 is driven by the cylinder 38 under the plate-like members 36 a and 36 b and the pressing member 42. It is pinched by.
[0030]
Through the above preparation steps, the dresser 20 is rotated at one end side of the grinding wheel 12 with a predetermined cutting amount (in this case, 3 μm) while rotating the dresser 20, and the dresser 20 is connected to the other end of the grinding wheel 12. The dressing is started by being displaced toward the side at a predetermined feed rate (in this case, 0.3 mm / rev) (step S1). Therefore, the surface of the grinding wheel 12 is revised and reshaped. At this time, grindstone particles are generated by dressing from the grinding wheel 12, and the grindstone particles are sucked by the suction nozzle 22 (see FIG. 3). For this reason, it is prevented that the surface of the valve stem 14 or the adjustment wheel 18 is damaged by the grindstone particles.
[0031]
Next, the support members 30a and 30b are displaced in the direction away from the grinding wheel 12, while the plate members 36a and 36b and the pressing member 42 are displaced in the circumferential direction of the grinding wheel 12 to grind the valve stem 14. Supply is performed between the grindstone 12 and the adjustment wheel 18 (step S2), and the cylinder 38 is driven to displace the pressing member 42 in a direction away from the umbrella portion 48 to release the clamping state of the umbrella portion 48. . For this reason, the valve stem 14 receives the rotational force from the adjusting wheel 18 and rotates, and the shaft portion 16 is ground by the grinding wheel 12 (step S3). At this time, the valve stem 14 is cooled by the grinding coolant discharged from the grinding coolant discharge nozzle 26, and the valve stem 14 is prevented from being heated.
[0032]
When the shaft portion 16 of the valve stem 14 is ground for a predetermined time, the cylinder 50 is driven, and the valve stem 14 is pushed out by the cylinder rod 52 into the passage 54 and conveyed (step S4). The valve stem 14 pushed out into the passage 54 rotates the passage confirmation detecting plate 56 that is projected out toward the passage 54. Therefore, the rotation detection sensor 58 detects that the valve stem 14 has passed through the passage confirmation detection plate 56 of the passage 54. Then, the valve stem 14 moves from the passage 54 to the next step.
[0033]
During the above process, it is determined whether or not a predetermined number, in this case, seven valve stems 14 have been ground (step S5). If the predetermined number has not been reached, steps S2 to S4 are repeated. Then, the next valve stem 14 is ground.
[0034]
When a predetermined number of valve stems 14 are ground in step S5, the process returns to step S1, and dressing of the grinding wheel 12 is started again by the dresser 20.
[0035]
As described above, since the dressing is performed while grinding the shaft portion 16 of the valve stem 14, it is not necessary to stop the grinding process for the dressing, the manufacturing time can be shortened, and the production efficiency is improved. .
[0036]
At the time of dressing, the diameter of the grinding wheel 12 is slightly reduced at the dressed portion of the grinding wheel 12, and a step is generated in the grinding wheel 12 during dressing (see FIG. 4). For this reason, this level | step difference will be transcribe | transferred to the axial part 16 of the valve stem 14, and there exists a possibility that a dimensional error may generate | occur | produce and grinding processing precision may fall. Therefore, it is necessary to improve the grinding accuracy by setting the cutting depth A small.
[0037]
FIG. 5 shows the swell size B and cylindricity (the one end side and the other end side of the shaft portion 16) representing the grinding accuracy of the shaft portion 16 of the valve stem 14 when the cutting amount A by the dresser 20 is changed. A graph of the difference in diameter from C). From these graphs, if the cutting depth A is in the range of 1 to 10 μm, machining accuracy equivalent to or higher than the swell size (0.003 mm) and cylindricity (0.010 mm) in the prior art is obtained. I understand.
[0038]
The time T1 required for dressing the grinding wheel 12 and the time T2 required for grinding the shaft portion 16 of one valve stem 14 are determined from the processing accuracy and equipment capability of the dressing apparatus 10, In this embodiment, if T1 and T2 are set to 28 seconds and 5.8 seconds, respectively,
T1 / T2 = 28 / 5.8 = 4.82
Thus, grinding can be performed on the shaft portions 16 of the four valve stems 14 while dressing the grinding wheel 12, while the shaft portion 16 of the fifth valve stem 14 is being ground. It turns out that the dressing is finished. If there is a time during which no grinding process is performed during dressing, the production efficiency is lowered. Therefore, the number n of the shaft portions 16 of the valve stem 14 to be ground by one dressing is:
n> T1 / T2
And That is, in this embodiment,
n> T1 / T2 = 4.82 (1)
To 5 or more.
[0039]
If the wear amount of the grinding wheel 12 is larger than the cut amount A, the surface waviness of the grinding wheel 12 cannot be sufficiently removed by dressing, and the grinding wheel 12 is ground. Further, the shaft portion 16 of the valve stem 14 may be bent. Therefore, the number n of the valve stems 14 to be ground is set to be small so that the wear amount of the grinding wheel 12 during one dressing is smaller than the cutting amount A.
[0040]
Here, since the diameter of the valve stem 14 changes when the grinding wheel 12 is worn, the wear amount of the grinding wheel 12 can be obtained by measuring this diameter. Therefore, FIG. 6 is a graph showing a change in the diameter D of the valve stem 14 with respect to the number n of the shaft portions 16 of the valve stem 14 to be ground by one dressing.
[0041]
From this graph, when the number n of the shaft portions 16 of the valve stem 14 to be ground by one dressing is 10, the change in the diameter D of the shaft portion 16 of the valve stem 14 is the cut amount set as described above. Since it is smaller than the maximum value of A (10 μm), the number n of the shaft portions 16 of the valve stem 14 to be ground while dressing the grinding wheel 12 once needs to be 10 or less.
[0042]
That is, in consideration of the formula (1), it is preferable that the number n of the shaft portions 16 of the valve stem 14 to be ground while the grinding wheel 12 is dressed once is 5 to 10.
[0043]
FIG. 7 shows a graph of the number of shaft portions 16 of the valve stem 14 that can be dressed when the feeding speed E of the dresser 20 is changed. When the feed speed E of the dresser 20 is slow, the surface roughness of the finished surface of the grinding wheel 12 is good, and the number of shaft portions 16 of the valve stem 14 that can be dressed by the grinding wheel 12 is large. When the speed E is increased, the surface roughness of the finished surface of the grinding wheel 12 becomes rough, and when the shaft portion 16 of the valve stem 14 is dressed many times by the grinding wheel 12, the processing accuracy of the shaft portion 16 of the valve stem 14 is increased. It will decline. For this reason, the number of the axial parts 16 of the valve stem 14 which can be dressed falls. As shown in FIG. 7, when the feed speed E of the dresser 20 is set within a range of 0.1 to 0.5 mm / rev, the number of shaft portions 16 of the valve stem 14 that can be dressed is as large as 43, that is, The surface roughness of the finished surface of the grinding wheel 12 is good, and the grinding ability of the grinding wheel 12 is improved.
[0044]
According to the present embodiment, since the grinding wheel 12 is dressed while grinding the shaft portion 16 of the valve stem 14 with the grinding wheel 12, it is not necessary to stop the grinding process at the time of dressing. Manufacturing time can be shortened and production efficiency is improved.
[0045]
In addition, by setting the cutting amount of the dresser 20 with respect to the grinding wheel 12 to an appropriate value, the undulation size B and the cylindricity C of the shaft portion 16 of the ground valve stem 14 are equal to or higher than those of the prior art. Machining accuracy.
[0046]
Further, by setting the feeding speed E of the dresser 20 to an appropriate value, the surface roughness of the finished surface of the grinding wheel 12 to be dressed is improved, and the valve stem 14 ground by the grinding wheel 12 is improved. The processing accuracy of the shaft portion 16 is further improved.
[0047]
Furthermore, when dressing the grinding wheel 12, grindstone particles are generated. The grindstone particles are sucked by the suction nozzle 22. Therefore, the grindstone particles are not caught in the rotation of the grinding grindstone 12, and the shaft portion 16 of the valve stem 14 and the surface of the adjusting wheel 18 are prevented from being damaged.
[0048]
【The invention's effect】
According to the dressing method and apparatus for a grinding wheel for valve stem according to the present invention, the following effects and advantages can be obtained.
[0049]
Since dressing is performed while grinding the shaft portion of the valve stem, it is not necessary to stop the grinding process at the time of dressing, the manufacturing time can be shortened, and the production efficiency is improved.
[0050]
Further, by setting the cutting amount of the dresser with respect to the grinding wheel to an appropriate value, it is possible to improve the processing accuracy of the shaft portion of the valve stem that has been ground.
[0051]
Furthermore, by setting the dresser feed speed to an appropriate value, it is possible to finish the surface roughness of the dressed grinding wheel so that the shaft stem of the valve stem can be ground by a predetermined number. The processing accuracy of the shaft portion of the valve stem ground by the grinding wheel is further improved.
[0052]
Furthermore, grindstone particles are generated by dressing from the grinding wheel, and the grindstone particles are sucked by the suction mechanism. For this reason, the grindstone particles are not involved in the rotation of the grinding grindstone, the surface of the valve stem and the adjustment wheel is prevented from being damaged, and the life of the adjustment wheel is extended.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing a dressing device for a grinding wheel for valve stem according to an embodiment of the present invention.
FIG. 2 is a flowchart for explaining a dressing method for a grinding wheel for valve stem according to an embodiment of the present invention.
FIG. 3 is a schematic partial cross-sectional side view showing the operation of the dressing apparatus of FIG. 1;
4 is an enlarged partial cross-sectional view showing a state in which a valve stem is ground by the dressing apparatus of FIG. 1;
FIG. 5 is a graph showing the swell size and cylindricity when the depth of cut is changed in the dressing method for a valve stem grinding wheel according to the present embodiment.
FIG. 6 shows a method for dressing a grinding wheel for a valve stem according to the present embodiment; the diameter of the shaft portion when the number of shaft portions of the valve stem is changed when grinding after dressing of the grinding wheel. It is a graph which shows a change.
7 is a graph showing the number of shaft portions of a valve stem that can be ground when the dresser feed speed is changed in the dressing method for a grinding wheel for valve stem according to the present embodiment. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Dressing apparatus 12 ... Grinding wheel 14 ... Valve stem 16 ... Shaft part 18 ... Adjustment wheel 20 ... Dresser 22 ... Suction nozzle 38, 50 ... Cylinder 48 ... Umbrella part 54 ... Passage

Claims (4)

A dressing method in which a dresser is brought into contact with a grinding wheel for grinding a shaft portion of a valve stem,
The amount of cut of the dresser is set so that the shaft portion of the valve stem that has been ground has a predetermined processing accuracy,
The number of shaft portions of the valve stem to be ground while dressing the grinding wheel once is divided by the time required to grind one shaft portion of the valve stem from the time required for one dressing. Is set so that the amount of wear of the grinding wheel is smaller than the depth of cut,
The dresser feed speed is set to a speed at which the surface roughness of the finished surface of the dressed grinding wheel is finished until a predetermined number of shaft portions of the valve stem can be ground .
A dressing method for a grinding wheel for a valve stem, characterized in that dressing is performed while suctioning the grindstone particles generated during the dressing. The method of claim 1, wherein
The depth of cut is set to 1 to 7 μm, the number of valve stems to be ground while dressing the grinding wheel once is set to 5 to 10, and the dresser feed speed is set to 0.1 to 0.5 mm / rev. A method for dressing a grinding wheel for a valve stem, characterized in that: The method according to claim 1 or 2 , wherein
The valve stem grinding is characterized in that, in the dressing step, dressing is performed by displacing the dresser formed narrower than the grinding wheel in the axial direction while being cut into the grinding wheel. Dressing method for processing wheel. A grinding wheel that is formed in a substantially cylindrical shape and abuts against the shaft portion of the valve stem while rotating to perform grinding.
A dresser that is formed in a substantially disk shape, cut into the grinding wheel while rotating, and displaced in the axial direction to dress the grinding wheel;
A suction mechanism for sucking the grinding stone particles generated when dressing the grinding wheel;
A dressing device for a grinding wheel for a valve stem, comprising:

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