KR0137094B1 - Method and device for honing work - Google Patents

Abstract

(purpose)

During the honing process, the pressing pressure of the grindstone against the grindstone is uniformed in response to the change in the inner diameter along the axial direction of the grind hole to uniformize the cross hatch formed on the grind hole.

(Configuration)

The expansion pressure by the expansion pressure applying means 21 is increased in the upper dead center portion 15a near the machining bore diameter of the cylinder bore 15, and the expansion pressure is lowered in the vicinity of the bottom dead center portion 15b by the small bore diameter inside. do. As a result, the pressing pressure against the machining hole inner surface 16 by the grindstone 29 is uniformed over the entire length of the cylinder bore 15, and the clarity of the cross hat is also uniform.

Description

Honing processing method and honing processing device

1 is an overall configuration showing a honing processing state by the honing processing apparatus showing an embodiment of the present invention.

2 is an explanatory view showing the change in the expansion pressure from the start of honing processing to the end in the honing processing apparatus of FIG.

3 is a characteristic diagram of the expansion pressure due to the axial position of the cylinder bore in the final finishing precision machining in FIG.

4 is a characteristic diagram illustrating the change in expansion pressure in more detail in accordance with the shape of the bore that shows the change in expansion pressure.

FIG. 5 is an explanatory diagram showing the intelligibility of the cross hatch of the inner surface of the cylinder bore formed by the change in the expansion pressure of FIG.

6 is a cross-sectional view showing various shapes of the cylinder bore.

7 is a characteristic diagram of change in expansion pressure corresponding to various shapes of the cylinder bore in FIG.

8 is an overall configuration showing a honing processing state by the honing processing apparatus according to the prior art.

9 is a cross-sectional view of the honing head in the honing machine according to FIG.

10 is a cross-sectional view when the inner surface of the machining hole is tapered in the cylinder bore.

11 is an operation explanatory diagram showing a honing processing state by a conventional honing processing apparatus for a cylinder bore of the shape of FIG.

12 is a contact pressure characteristic diagram showing the contact pressure of the grindstone of the honing machining of FIG.

13 is a schematic diagram of a cross hatch formed on the inner surface of a processing hole by honing;

FIG. 14 is an explanatory diagram showing the clearness of the cross hat corresponding to the contact pressure caused by the grindstone of FIG. 12; FIG.

FIG. 15 is an explanatory diagram showing a change in the expansion pressure from the start of honing to the end of the honing processing apparatus of FIG. 8; FIG.

(Explanation of the sign)

1 cylinder block 3 cylinder bore 5 honing head

7: grindstone 9: tapered cone 11: shoe

13 cylinder block 15 cylinder bore 17 honing head

21: expansion pressure applying means 23: spindle

25: taper cone 27: shoe 29: grindstone

31: air passage 33: air nozzle (inner diameter detection means)

35: air piping 37: air micro mater

39: control circuit (control means)

This invention honing the grinding grinds the inner surface of the processing hole by the honing head to which the grinding wheel is attached is axially moved along with the rotation while the grinding grindstone is expanded and moved to a predetermined expansion pressure with respect to the processing hole inner surface of the workpiece. It relates to a processing method and a honing processing device.

For precision finishing on the inner surface of the workpiece bore, for example, the cylinder bore of the engine, honing is generally used for grinding, while the honing head with the grindstone rotates in an axial movement, ie up and down. Location 56-76374)

8 is an operation explanatory diagram showing the ecology of honing the cylinder bore 3 of the cylinder block 1 of the engine. Many grindstones 7 are attached to the outer circumference of the honing head 5. 9 is a cross-sectional view showing the internal structure of the honing head 5, wherein the honing head 5 has a tapered cone 9 for expanding the grindstone, and the grindstone 7 is formed of the tapered cone 9. It is mounted on the outer circumference of the shoe 11 which is movable in the direction of approach and departure from the cylinder bore inner surface by the shangdong.

The tapered cone 9 is provided with a pressure (extension pressure) P in the axial direction by a hydraulic mechanism or the like not shown, and the shoe 11 moves outward by the downward movement of the tapered cone 9. In addition, the grindstone 7 also moves in the same direction to impart a pressing (contact) pressure on the inner surface of the cylinder bore 3. As the honing head 5 rotates and moves in this state, the inner surface of the cylinder bore 3 is honed.

In general, the cylinder block is manufactured by casting, and then rough processing is performed by boring, but at this point, that is, before the honing processing, which is a precision finish, the inner shape of the cylinder bore is used to vary the rigidity of the cylinder bore itself. In many cases, it does not become a perfect cylindrical shape due to the distribution of heat capacity.

FIG. 10 shows a case where the cylinder bore 3 has a tapered shape where the piston top dead center 3a is wide and the piston bottom dead center 3b is narrow. It is a multi-sided view which shows the situation in the process of honing with respect to the taper-shaped cylinder bore 3 with the same end. 11 (a) is near the tip A of the grindstone 7 at the center A of the cylinder bore 3, and 11 (b) is near the bottom B of the cylinder bore 3 at the end of the cylinder bore 3 If yes. Here, the grindstone 7 is pressed against the inner surface of the cylinder bore by the pressing (contact) pressure according to the constant expansion pressure over the entire length of the cylinder bore 3, but in fact the honing head 5 moves up and down at high speed. Therefore, in the case of the tapered shape of the cylinder bore 3, the contact pressure near the distal end of the bore grindstone 7 becomes higher than the other portions, and the bottom dead center of the contact bore of the grindstone 7 with the inner diameter of the cylinder bore is small. The vicinity 3b is high and the top dead center area 3a with a large internal diameter is low.

FIG. 12 shows the contact pressure of the grindstone 7 corresponding to the axial position from the tapered cylindrical bore upper end as described above, and accordingly, the contact pressure caused by the grindstone 7 is shown in FIG. 11 (a). It rises sharply from the vicinity of A of the cylinder bore center shown in FIG. 11, and reaches the maximum at the lowermost portion B of the cylinder bore shown in FIG. 11 (b).

On the other hand, in the grinding wheel used for honing processing, abrasive grains such as diamond are usually used, and the honing head to which the grinding wheel is attached is rotated and moved up and down by a rotating motor and a vertical cylinder, so that the trajectory of the abrasive grain is helical and the honing head is As shown in FIG. 13, the lattice-shaped groove | channel which is peculiar to a honing process is formed in the moving process hole inner surface. The cross hatch is formed by intersecting two kinds of helical grinding grooves (a) and (b) having different inclined directions on the inner surface of the processing hole. The oil pit helps oil retention or diffusion on the inner surface of the cylinder bore of the engine. plays the role of a pit.

Such cross hatches are preferable to perform the role of the oil pit so that the inclination angle or thickness is uniform and clear about the cylinder bore surface evenly or at least near the top dead center where the piston ring is perturbed, and is suitable for the performance of the engine. If it does not perform a sufficient role as an oil pit, the oil is not sufficiently maintained, causing an increase in oil consumption and causing an initial scarf of the piston.

The cross hatch is determined by the contact pressure on the inner surface of the cylinder bore of the grinding wheel, the higher the contact pressure tends to be clearer. Therefore, when the shape of the cylinder bore is tapered in which the inner diameter of the bottom dead center becomes small as described above, as shown in FIG. 14, the degree of intelligibility of the cross hat near the bottom dead center where the contact pressure to the inner surface of the cylinder bore by the grinding wheel is high is high. On the contrary, the clarity near the top dead center is low, and the uniformity of the cross hatch is not achieved, and the top dead center near the top dead center which needs to be cleared as an oil pit is reversed, thereby increasing the oil consumption and the initial scarf of the piston. It causes.

In honing processing, the expansion pressure applied to the grindstone is generally divided into three stages of high pressure, medium pressure, and low pressure from the beginning to the end of the processing, as shown in Fig. 15. Since the expansion pressure of the grindstone is constant, the tapered cylindrical bore of the tip is the same at high and medium pressures, but at the low pressure of the final finishing, the pressing pressure by the grindstone becomes higher at the lowermost level so that the cross hatch is uneven overall. It becomes one.

The object of the present invention is to equalize the cross hatch formed on the inner surface of the processing hole by changing the expansion pressure applied to the grindstone in response to the change in the inner diameter of the processing hole.

In order to achieve the above object, the present invention provides an expansion pressure to the grinding wheel installed in the honing head, and expands and moves toward the inner surface of the processing hole, while the honing head is rotated and axially moved while being pressed by the inner surface of the processing hole. In the honing processing method for grinding, the expansion pressure is increased for a portion of the inner diameter of the processing hole while the expansion pressure is lowered for a portion with a small inner diameter.

Further, in the above method, the inner diameter of the processing hole is measured along its axial direction based on the inner diameter detecting means installed in the honing head during a series of operations of honing processing for the processing hole, and based on the measured inner diameter dimension. It is a method of honing.

On the other hand, the grinding wheel installed in the honing head is extended by the expansion pressure applying means, and expands and moves toward the inner surface of the processing hole, and the honing head rotates and moves in the axial direction while being pressed by the inner surface of the processing hole. In the honing processing apparatus for grinding, the expansion pressure is increased for a portion of the inner diameter of the processing hole on the basis of the inner diameter detecting means for detecting the inner diameter of the processing hole and the detected value of the inner diameter detecting means. The control means for controlling the expansion pressure applying means is provided for the portion having the small inner diameter so as to lower the expansion pressure.

Further, in the above configuration, the inner diameter detecting means is provided in the honing head.

According to the above method or configuration, the expansion pressure is increased for the portion of the inner diameter of the drilled hole, while the expansion pressure is lowered for the portion of the inner diameter of the drilled hole while the inner diameter is different in the axial direction. The pressing pressure on the inner surface of the processing hole is uniformized over the entire length of the processing hole, and the cross hatch of the inner surface of the processing hole formed by the honing process is also uniformized.

Further, according to the above method or configuration, the inner diameter detection means provided in the honing head is used to measure the inner diameter of the processing hole during a series of operating processes in the honing process, thereby preventing deterioration of workability due to the inner diameter measurement.

An embodiment of this invention will be described below with reference to the drawings.

FIG. 1 shows a state in which the machining hole inner surface 16 of the cylinder bore 15 in the cylinder block 13 of an automobile engine is honed by a honing machine according to an embodiment of the present invention. The honing head 17 has two tapered cones 25 which are inserted into the main body 19 and installed on the main shaft 23 which can be moved up and down by expansion pressure applying means 21 such as a hydraulic cylinder that generates an expansion pressure P. The shoe 27 is pressed against the inner surface of the processing hole 16 by the lowering of the tapered cone 25, and the inner surface of the processing hole 16 is mounted on the outer surface of the shoe 27 and the outer surface of the shoe 27. The rectangular grindstone 29 of the rectangular parallelepiped long in the vertical direction is provided in the figure to process.

The honing head 17 is formed by the taper cone 25 and the shoe 27 by the pressing pressure of the grindstone 29 on the inner surface 16 of the processing hole of the cylinder bore 15 based on a predetermined expansion pressure P. In the depressed state, honing processing is performed while rotating up and down simultaneously with the up and down cylinders and motors (not shown) as a driving source as a whole.

In addition, an air passage 31 extending in the vertical direction is formed in the main body 19 of the honing head 17. The air passage 31 constitutes an air nozzle 33 in which the lower side opens to face the machining hole 16 during a series of operations of honing. The upper side opens to the upper surface and is connected to the air micrometer 37 via the air pipe 35.

The air nozzle 33, the air micrometer 37, and the like constitute an inner diameter detecting means. The air micrometer 37 blows air from the air nozzle 33 to the processing hole inner surface 16 to convert the back pressure into an electrical signal to control the inner diameter of the processing hole of the cylinder bore 15 corresponding to the back pressure. It is calculated by the control circuit 39 as a means. The control circuit 39 controls to change the expansion pressure P in accordance with the inner diameter dimension calculated for the expansion pressure pouring means 21.

Here, the shape of the machining bore of the cylinder bore 15 in FIG. 1 is tapered in the shape of the piston bore 15a wider and the bottom dead center 15b narrower than that shown in FIG.

In the honing of the cylinder bore 15, as shown in FIG. 2, the expansion pressure is increased immediately after the start of the machining, thereby eliminating the loading of the grindstone 29 during the preceding machining. Doel which performs the so-called self-dressing, then lowers the extension pressure to medium pressure until the target machining diameter is reached, and then expands the pressure to low pressure to increase surface roughness and processing accuracy. dwell).

At low pressure, the expansion pressure P is changed in accordance with the taper shape of the cylinder bore 15 in dwell processing. That is, as shown in FIG. 3, the expansion pressure P applied to the grindstone 29 is made high near the top dead center 15a which has a large internal diameter, and low near the bottom dead center 15b, and final finishing is performed.

In this way, the change in the expansion pressure P changes the back pressure of the air blown from the air nozzle 33 toward the machining hole inner surface 16 according to the vertical movement of the honing head 17 prior to the low pressure doel processing. By the detection, the control circuit 39 calculates the inner diameter from the upper dead center region 15a to the lower dead center region 15b. Based on this, the control circuit 39 calculates the expansion pressure P by the expansion pressure applying means 21. The third degree is changed. At this time, the measurement of the inner diameter is carried out in a series of processing operations from the start of processing in the honing process to the end of the processing, thereby maintaining good workability.

FIG. 4 shows a state in which the expansion pressure is changed more finely in response to the contact pressure of the grindstone in FIG. 12 shown in the prior art, that is, in response to the shape change of the inner diameter dimension.

As described above, when the inner surface 16 of the bore hole 15 is machined, the expansion pressure P is increased on the upper dead center portion 15a side with a large inner diameter value, while on the lower dead center portion 15b side with a small inner diameter dimension. By lowering the expansion pressure P, the pressing pressure to the machining hole inner surface 16 by the grindstone 29 is almost uniform over the entire length of the cylinder bore from the top dead center 15a to the bottom dead center 15b.

As the pressing pressure becomes uniform, the grinding trajectory of the grinding wheel 29 formed on the inner surface 16 of the processing hole 16 as the honing head 17 rotates and moves up and down is applied to the entire length of the cylinder bore 15 as shown in FIG. In the vicinity of the top dead center 15a that is substantially uniform over the inside and particularly has a large inner diameter, the extension pressure P is increased to clarify the cross hatch of the piston ring perturbation portion like other portions. The cross hatch formed in this way is sufficient to maintain the oil to serve as an oil pit, and to form the oil consumption performance and the initial scarf performance of the piston.

In the above embodiment, the cylinder bore 15 has a tapered shape having a large inner diameter near the top dead center 15a. However, as shown in FIGS. 6 (a), (b) and (c), The inner shape of the cylinder bore is narrow at the top dead center 15a side and wide at the bottom dead center 15b side, i.e., the taper shape in which the tenth degree is inverted up and down (a), near top dead center 15a and bottom dead center. Long-blind shape that is wider at the vicinity 15b and narrows at the central portion 15c, on the contrary, it is narrower at the top dead center 15a and bottom dead center 15b and larger in the central portion 15c. As shown in Figs. (7) (a), (b), and (c), the expansion pressure is increased for the portions having large inner diameters, and the expansion pressure is decreased for the portions having small inner diameters, respectively. To equalize the pressing pressure on the inner surface of the hole by the grinding wheel It can be anecdote.

In the present embodiment, the inner diameter of the cylinder bore 15 is measured by using an air micrometer 37 installed in the honing head 17 prior to Doel processing, which improves the surface roughness and roughness of the machined surface. However, the inner diameter of the cylinder bore 15 is measured by a dedicated measuring device separate from the honing processing apparatus, the measurement data is input to the control circuit 39, and the expansion pressure means 21 controls the expansion pressure according to this input value. You may also do so.

As described above, according to the first invention or the third invention, the expansion pressure applied to the grinding wheel provided in the honing head is increased for a portion having a large inner diameter of the processing hole, while at a portion having a small inner diameter. Since the inner diameter is different in the axial direction, even if the inner diameter is different, the pressing pressure is equalized over the entire length of the processing hole by the grinding wheel, and the cross-hatching of the inner surface of the processing hole formed by the honing is also performed. To be uniform.

According to the second invention or the fourth invention, since the inner diameter of the processing hole is measured by the inner diameter detecting means provided in the honing head, from the inner diameter measurement to the honing processing according to the change in the expansion pressure according to the inner diameter measurement. This operation can be performed by a series of processing operations, and workability can be maintained well.

Claims (4)

In the honing processing method in which the grinding grindstone installed in the honing head is provided with an expansion pressure and is expanded and moved toward the inner surface of the processing hole, pressed by the inner surface of the processing hole, the honing head is rotated and moved in the axial direction for grinding. , Honing processing method characterized in that the expansion pressure is increased for the portion of the inner diameter of the processing hole is high, while the expansion pressure is lowered for the portion with the small inner diameter. The method of claim 1, During the series of honing operations for the processing holes, the inner diameter of the processing holes is measured along the axial direction by the inner diameter detecting means provided in the honing head, and honing is performed based on the measured inner diameter values. Honing processing method. The grinding wheel installed in the honing head is extended by the expansion pressure imparting means, and expands and moves toward the inner surface of the processing hole. The grinding wheel rotates and axially moves while being pressed by the inner surface of the processing hole. Honing processing apparatus, On the basis of the inner diameter detecting means for detecting the inner diameter of the processing hole and the detected value of the inner diameter detecting means, a hole is used to increase the expansion pressure for the portion with the large inner diameter of the processing hole, and the expansion pressure for the portion with the small inner diameter. And a control means for controlling the expansion pressure applying means so as to lower the honing processing device. The method of claim 3, wherein Honing apparatus, characterized in that the inner diameter detecting means is installed in the honing head.