JP3077464B2 - Honing method and honing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a honing method and a honing apparatus for stabilizing a processing time.

[0002]

2. Description of the Related Art Honing is a process in which the inner surface of a cylindrical processing hole, such as a cylinder bore of an internal combustion engine, to be processed is ground using a grindstone. It is arranged at a plurality of equal intervals in the circumferential direction with the axial direction as the longitudinal direction. The plurality of whetstones are inserted into the processing hole and pressed against the inner surface of the processing hole by a tool called a horn arranged radially with respect to the center axis thereof, and are processed by rotating and reciprocating in the axial direction. The inner surface of the hole is processed smoothly and accurately.

[0003] In such honing, by stabilizing the processing time for one workpiece,
Workability is improved, and processing costs can be reduced. As a technique for stabilizing the processing time, there is a technique described in, for example, JP-A-64-51266. The technique described in this publication, when the processing time is equal to or longer than a preset time, sharpens the grinding wheel by increasing the expansion pressure by the radially arranged horns pressing the grinding stone against the inner surface of the processing hole, assuming that the grinding stone is clogged by grinding chips. Debris is removed and clogging is eliminated, thereby stabilizing the processing time.

[0004]

The grindstone used in the honing process is obtained by hardening abrasive grains with a binder (binder), and since the abrasive grains are scattered in the binder, the use time of the grindstone increases. Accordingly, a state in which the abrasive grains appear on the surface and a state in which the abrasive grains do not appear on the surface but the binder does appear on the surface are repeated. As a result, the processing time T for one workpiece changes regularly so as to draw a sine wave around the appropriate processing time T _M as shown in FIG. For this reason,
As in the prior art described in the above-mentioned publication, stabilization of the processing time by eliminating clogging alone is not enough to stabilize the processing time, and there is room for improvement. The machining time T here is a machining diameter D ₁ obtained by rough machining in a state of a diameter D ₀ before machining of the machining hole as shown in FIG.
Is that the finishing time until processing diameter D ₂ obtained by finishing the.

Therefore, an object of the present invention is to further stabilize the processing time in honing processing.

[0006]

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention firstly sets a target time required for a previous machining time when the inner surface of a machining hole of a workpiece is ground with a grindstone to perform honing. When the processing time exceeds, the pressing pressure on the inner surface of the processing hole by the grindstone is increased for a predetermined time, then returned to the normal pressure and the current processing is performed, and the previous processing time was shorter than the target processing time. At this time, the pressure applied to the inner surface of the processing hole by the grindstone is reduced for a predetermined time and then returned to the normal pressure to perform the current processing.

Secondly, as shown in FIG. 1, processing time detecting means 23 and 25 for detecting honing processing time for grinding the inner surface of a processing hole of a workpiece with a grindstone, and pressing pressure of the grinding stone against the inner surface of the processing hole. Pressure varying means 15 and 29 for changing the machining time, a storage means 27a for storing the allowable machining upper limit time and machining lower limit time of the honing machining time, respectively, and the honing machining time detected by the machining time detecting means 23 and 25. When the time exceeds the processing upper limit time stored in the storage means 27a, the pressure applied to the inner surface of the processing hole by the grindstone is increased for a predetermined time and then returned to the normal pressure, while the processing time detecting means 23, 25 When the detected honing processing time falls below the processing lower limit time stored in the storage means 27a, the pressing pressure of the grinding stone against the inner surface of the processing hole is reduced. Some as structure and a control unit 27b for controlling the pressing pressure varying means 15 and 29 to return to normal pressure after reducing a predetermined time.

[0008]

[0009]

According to the first method or the second configuration, when the previous machining time exceeds the target machining time, the surface roughness of the machined hole is correspondingly finer than the appropriate value, and Therefore, in this processing, the surface roughness approaches an appropriate value by increasing the pressing pressure on the inner surface of the processing hole by the grindstone. As a result, it is necessary to reduce the processing time, and the processing time approaches the target processing time. On the other hand, if the previous machining time is less than the target machining time,
Correspondingly, the surface roughness of the machined hole is coarser than the appropriate value,
For this reason, in this processing, the surface roughness approaches the appropriate value by reducing the pressing pressure on the inner surface of the processing hole by the grindstone,
As a result, it is necessary to increase the processing time, and the processing time approaches the target processing time. The processing performed by increasing the pressing pressure on the inner surface of the processing hole by the whetstone and the processing performed by lowering the pressing pressure are performed for a predetermined time, and thereafter the pressing pressure is performed at a normal pressure. As a result, the surface roughness of the machined hole approaches a more appropriate value.

According to the third method or configuration, the processing performed by increasing the pressing pressure on the inner surface of the processing hole by the grindstone and the processing performed by lowering the pressing pressure are both performed for a predetermined time, and thereafter the pressing pressure is reduced. It is performed under normal pressure. As a result, the surface roughness of the machined hole approaches a more appropriate value.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic configuration diagram of a honing apparatus showing one embodiment of the present invention. This figure shows a state in which a horn 3 is inserted into a processing hole 1, which forms a cylinder bore of an internal combustion engine, for example, a workpiece. The horn 3 includes a main body 5, two tapered cones 7 that are vertically movably inserted into a center hole 5 a of the main body 5,
A plurality of shoes 9 are pressed toward the inner surface of the processing hole 1 by being lowered, and are arranged in the circumferential direction. And a whetstone 11 in the shape of a circle.

The tapered cone 7 is formed with a downwardly inclined surface 7a so as to reduce the diameter on the lower side, while the shoe 9 is formed with an upwardly inclined surface 9a which comes into contact with the inclined surface 7a. I have.

A cylindrical portion 7b is formed above the inclined surface 7a of the tapered cone 7, and the outer peripheral surface of the cylindrical portion 7b is in sliding contact with the center hole 5a of the main body 5. The taper cone 7 is
It is supported by a central shaft 13, and the upper end of the central shaft 13 is connected to a piston 17 of a hydraulic cylinder 15.

The shoe 9 is disposed in a vertically long groove formed in the main body 5 and moves outward in the radial direction of the center shaft 13 as shown by an arrow A by machining of the taper cone 7 to process the grindstone 11. It presses against the inner surface of the hole 1 with a predetermined pressing pressure, that is, an expansion pressure.

The horn 3 works together with the hydraulic cylinder 15 by using a vertical drive cylinder and a rotary drive motor (not shown) as drive sources, and performs the vertical operation while simultaneously grinding the inner surface of the processing hole 1 while rotating.

An air passage 19 is formed in the main body 5 and extends in the vertical direction. The air passage 19 has an air nozzle 21 whose lower part is open to face the inner surface of the processing hole 1 and whose upper part is open on the upper surface. Connected to the air micrometer 23. The air micrometer 23 converts the back pressure at that time into an electric signal by blowing air from the air nozzle 21 to the inner surface of the processing hole 1, and calculates a predetermined processing size of the processing hole 1 according to the back pressure. . The processing time calculation circuit 25 connected to the air micrometer 23 calculates the time required for the processing dimension calculated by the air micrometer 23 to reach a predetermined value (finish processing diameter D ₂ ) from the start of the finish processing in FIG. That is, the processing time T is calculated. Therefore, the air micrometer 23 and the processing time calculation circuit 25 constitute a processing time detecting means.

A control circuit 27 as a control means connected to the processing time calculation circuit 25 has a built-in memory as a storage means, and this memory allows a change in the processing time T shown in FIG. Upper limit value _TH and lower limit value _TL
Are stored. The control circuit 27 compares the stored upper limit value _TH and lower limit value _TL with the actual processing time T ₀ calculated by the processing time calculation circuit 25, and drives the hydraulic pump 29 based on the comparison result. Then, the piston 17 of the hydraulic cylinder 15 is moved up and down to control the expansion pressure by the shoe 9, that is, the pressing pressure for pressing the grindstone 11 against the inner surface of the processing hole 1. Therefore, the hydraulic pump 29 and the hydraulic cylinder 15 constitute a pressing pressure variable unit.

Here, the relationship between the processing time T and the surface roughness R of the inner surface of the processed hole is shown by a straight line a in FIG. According to this, the shorter the processing time T, the higher the surface roughness R becomes.
Is longer, the surface roughness R becomes finer, and there is a negative correlation between the two. In FIG. 3, the surface roughness R has an appropriate value at a position substantially at the center of the straight line a. The relationship between the processing pressure (expansion pressure) P and the processing time T is shown by a straight line b in FIG. According to this, the processing time T increases as the processing pressure P decreases, and conversely, the processing time T decreases as the processing pressure P increases.
There is also a negative correlation between these two.

[0020] Considering the correlation in FIG. 3 and FIG. 4 described above, the control circuit 27, when the machining time T exceeds the upper limit value T _H increases the working pressure P, conversely machining time T is the lower limit T _L If it falls below, the processing pressure P is reduced. The former processing pressure P
Is equivalent to the case where the machining time T is shortened from FIG. 4, and the surface roughness R is kept at an appropriate value from a fine state from FIG. On the other hand, when the latter processing pressure P is reduced, it corresponds to the case where the processing time T is increased from FIG. 4, so that the surface roughness R is maintained at an appropriate value from the rough state from FIG. 3. .

Further, the control circuit 27 incorporates a timer, this timer the previous machining time T is, processing time and at the current high pressure conditions in the case of exceeding the upper limit value T _H, the lower limit T _L The processing time in the low pressure state at this time when the value is less than is measured. The processing time at high pressure is 1/3 of the previous processing time T, and the processing time at low pressure is 1/2 of the previous processing time. Process.

FIG. 5 is a flowchart showing the operation of the honing apparatus configured as described above.
First, the processing time calculation circuit 25 reads the value of the processing diameter calculated by the air micrometer 23 (step 10).
1), it calculates the processing time T (step 103) to obtain an actual machining time T _0. Then, the control circuit 27 and processing time T _0, compared with the upper limit value T _H and the lower limit value T _L (step _{105), T L ≦ T 0} ≦ T H and is in machining time T ₀ is within the allowable time processing pressure P is set to normal pressure P _M as shown in FIGS. 6 (a) if (step 107).

[0023] When the machining time T ₀ is outside the allowable time, it is determined whether or exceeds the upper limit value T _H (step 109), exceeds the upper limit value T _H becomes T _H <T ₀ If, for the next machining for machining pressure P as shown in FIG. 6 (b) to enhance T _0/3 seconds as P _H (step 111, 113). That is, the hydraulic pump 29 is driven, the piston 17 of the hydraulic cylinder 15 is lowered, the taper cone 7 is lowered, and the shoe 9 is pressed in the direction of arrow A to increase the pressing pressure of the grinding stone 11 against the inner surface of the processing hole 1. T
After the high-pressure processing of _0/3 seconds, returns to the processing at normal pressure P _M.

By increasing the current processing pressure P in a state where the previous processing time T is long, the surface roughness R approaches the proper value from a fine state as shown in FIGS. 3 and 4, and the processing time T is accordingly reduced. It becomes necessary to shorten the machining time T, and the current machining time T approaches the target machining time T _M.

[0025] When the machining time T ₀ in step 109 does not exceed the upper limit value T _H is machining time T ₀ is the lower limit value T
It means that below the _{L (T 0 <T L)} , carried out the processing pressure P lowers T _0/2 seconds as P _L as shown in FIG. 6 (c) for the next processing (step 115, 1
17). That is, the hydraulic pump 29 is driven, the piston 17 of the hydraulic cylinder 15 is raised, the taper cone 7 is raised, and the pressure of the grindstone 11 via the shoe 9 against the inner surface of the processing hole 1 is reduced. After the low-pressure processing of T _0/2 seconds, returns to the processing at normal pressure P _M.

By lowering the current processing pressure P in a state where the previous processing time T has been shortened, the surface roughness R approaches the proper value from the rough state as shown in FIGS. 3 and 4, and the processing time T Needs to be lengthened, and the current processing time T approaches the target processing time T _M.

For example, for the processing time T, the lower limit value T _L
= 15 seconds, target value = 20 seconds, upper limit value T _H = 25 seconds,
When it becomes actual machining time T ₀ is 30 seconds, that is, if the machining time T ₀ exceeds the upper limit value T _H, the next time T
_0/3 = after high pressure processing for 10 seconds, will be processed until the processing diameter finish at normal pressure. Further, when the actual processing time T ₀ is 10 seconds, that is, when the processing time T ₀ is lower than the lower limit value _TL , the next time T _0/2 = 5 seconds low-pressure processing and then normal pressure It will be processed until it reaches the finish processing diameter.

[0028]

As described above, according to the first invention or the second invention, when the previous machining time exceeds the target machining time, during the current machining, the inner surface of the machining hole formed by the grindstone is removed. By increasing the pressing pressure, the machining time until the surface roughness of the inner surface of the machining hole reaches the target value is shortened, while if the previous machining time is shorter than the target machining time, At times, by reducing the pressing pressure, the processing time until the inner surface of the processing hole reaches the target surface roughness becomes longer, and as a result, the processing time approaches the target processing time to stabilize the processing time. Moreover, the surface roughness of the inner surface of the processing hole can be appropriately maintained. Then, the processing performed by increasing the pressing pressure on the inner surface of the processing hole by the grindstone, and the processing performed by reducing the pressing pressure,
In each case, after performing for a predetermined time, by performing processing with the pressing pressure as the normal pressure, the surface roughness of the inner surface of the processed hole can be made closer to an appropriate value.

According to the third aspect of the present invention, after the pressing performed on the inner surface of the processing hole by the grindstone by increasing the pressing pressure and the processing performed by lowering the pressing pressure are performed for a predetermined time, the pressing pressure is normally reduced. By performing the processing as the pressure, the surface roughness of the inner surface of the processed hole can be made closer to an appropriate value.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention.

FIG. 2 is a schematic overall configuration diagram of a honing apparatus showing one embodiment of the present invention.

FIG. 3 is a correlation diagram between a processing time and a surface roughness of a finish processing surface.

FIG. 4 is a correlation diagram between processing pressure and processing time.

FIG. 5 is a flowchart showing a machining operation in the honing machine of FIG. 1;

FIG. 6 is an explanatory diagram showing a processing pressure with a lapse of processing time in the honing apparatus of FIG. 1;

FIG. 7 is an explanatory diagram showing a change in processing time.

FIG. 8 is an explanatory diagram showing a finish processing time.

[Explanation of symbols]

 Reference Signs List 1 processing hole 11 grinding stone 15 hydraulic cylinder (pressing pressure variable means) 23 air micrometer (processing time detecting means) 25 processing time calculation circuit (processing time detecting means) 27 control circuit (control means, storage means) 29 hydraulic pump (pressing) Pressure variable means)

Claims (2)

(57) [Claims] When a previous processing time exceeds a target processing time when a honing process is performed by grinding an inner surface of a processing hole of a workpiece with a grindstone, a pressure applied to the inner surface of the processing hole by the grindstone. After increasing the pressure for a predetermined time, the pressure is returned to the normal pressure, the current processing is performed, and when the previous processing time is shorter than the target processing time, the pressure applied to the inner surface of the processing hole by the grindstone is reduced for a predetermined time. Honing processing method characterized by performing the current processing by returning to normal pressure. 2. A processing time detecting means for detecting a honing processing time for grinding an inner surface of a processing hole of a workpiece with a grindstone, a pressing pressure variable means for changing a pressing pressure of the grinding stone against the inner surface of the processing hole, and the honing processing. Storage means for storing the processing upper limit time and the processing lower limit time allowed for time, respectively, and when the honing processing time detected by the processing time detection means exceeds the processing upper limit time stored in the storage means, While raising the pressing pressure against the inner surface of the processing hole by the grindstone for a predetermined time and then returning to the normal pressure, when the honing processing time detected by the processing time detecting means falls below the processing lower limit time stored in the storage means, Control means for controlling the pressing pressure variable means so as to return the pressure to the normal pressure after reducing the pressing pressure on the inner surface of the processing hole by the whetstone for a predetermined time. A honing processing device comprising: