JP2023147664A - Honing processing method - Google Patents

Abstract

To restrain wear of a grindstone when performing honing processing.SOLUTION: A honing processing method includes a first step of determining a unit feed quantity based on a surface roughness of an inner peripheral surface of a workpiece and projection heights of abrasive grains on a grindstone used by being attached to a honing head, and a second step of processing the workpiece by starting rotation of the grindstone from a state where the grindstone and the workpiece are not in contact with each other, and gradually increasing a radius of rotation of the grindstone for each unit feed quantity in response to a change in grinding resistance.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a honing method.

Generally, in a cylinder block mounted on a vehicle, honing is performed on the inner circumferential surface of the bore portion during manufacturing or restoration. As described in Patent Document 1, in honing processing, while the honing head rotates, a grindstone included in the honing head is expanded in the radial direction and pressed against the inner circumferential surface of the bore, thereby cutting the bore. The inner circumferential surface of is ground.

Japanese Patent Application Publication No. 2006-175574

In a typical honing process, the cylinder head is expanded at a constant speed, and contact between the grinding wheel and the bore is confirmed when the grinding resistance exceeds a threshold value. However, when machining a bore part whose inner peripheral surface has become extremely uneven due to aging, etc., when the grinding wheel and the bore part come into contact, local contact between the convex part and the grinding wheel may occur. . In this case, an excessive load is applied to the grindstone, and the abrasive grains may locally fall off, which may cause significant wear and tear on the grindstone. Moreover, such a problem is common in honing processing in which grinding is performed not only on a bore portion but also on a workpiece surface with a large surface roughness.

The present disclosure can be realized as the following forms.

(1) According to one embodiment of the present disclosure, a honing method is provided. This honing method includes a first step of determining the unit feed amount based on the surface roughness of the inner circumferential surface of the workpiece and the protrusion height of the abrasive grains in the grindstone attached to the honing head; The rotation of the grindstone is started from a state where the grindstone and the workpiece are not in contact with each other, and the rotation radius of the grindstone is gradually expanded for each unit feed amount according to changes in grinding resistance. A second step of processing the workpiece.
According to this type of honing method, by gradually expanding the rotation radius of the grindstone for each unit feed amount, it is possible to gradually grind the convex part on the inner circumferential surface of the bore. It is possible to suppress the occurrence of locally excessive grinding resistance, and it is possible to suppress wear and tear on the grindstone.
(2) In the above embodiment, the second step may include a step of expanding the rotation radius by the unit feed amount each time the grinding resistance decreases by a predetermined displacement width.
According to this type of honing method, the radius of rotation of the grinding wheel is expanded by a unit feed amount every time the grinding resistance decreases by a predetermined displacement width, so a sudden increase in the grinding resistance can be suppressed, and wear and tear on the grinding wheel can be suppressed. can be further suppressed.
(3) In the above embodiment, in the first step, when the surface roughness is larger than the protrusion height, a feed amount smaller than the protrusion height is determined as the unit feed amount, and the surface roughness is The method may include a step of determining a feed amount having the same magnitude as the ejection height as the unit feed amount when the ejection height is less than or equal to the ejection height.
According to this type of honing method, when the surface roughness of the workpiece is larger than the protrusion height of the abrasive grains, the unit feed amount is set to be smaller than the protrusion height of the abrasive grains, so the grinding resistance can be further reduced, and wear and tear on the grindstone can be further suppressed. On the other hand, if the surface roughness of the workpiece is less than or equal to the protrusion height of the abrasive grains, the unit feed amount is set to the same feed amount as the abrasive grain protrusion height, so it is possible to suppress a decrease in grinding efficiency. .

FIG. 1 is an explanatory diagram showing a schematic configuration of a honing device according to the present embodiment. It is a flowchart which shows the procedure of the first half of a honing process. It is a flowchart which shows the procedure of the latter half of a honing process. It is a flowchart which shows the procedure of a quantitative expansion process.

A. Embodiment:
A1. Device configuration:
FIG. 1 is an explanatory diagram showing a schematic configuration of a honing device 1000 of this embodiment. The honing device 1000 includes a honing head 100, a drive section 200, and a control section 300. The honing device 1000 grinds the inner circumferential surface of the bore Wb of the cylinder block W by rotating and moving the honing head 100 up and down while the honing head 100 is in contact with the inner circumferential surface of the bore Wb of the cylinder block W. Process.

The honing head 100 includes a grinding section 110 and a rod 120. The grinding section 110 includes a head main body 111 and a plurality of grindstones 112. The head main body 111 has a cylindrical shape, and a plurality of grindstones 112 are provided on its outer peripheral surface at equal intervals along the outer periphery. The head main body 111 has a grindstone expansion mechanism (not shown), which allows the grindstone 112 to protrude from the outer peripheral surface of the head main body 111 to expand the rotation radius of the grindstone 112 during grinding. In this embodiment, the operator adjusts the amount of protrusion of the grindstone 112 by adjusting the amount of rotation of a ball screw (not shown) included in the main body of the honing device 1000.

The rod 120 is a cylindrical member, and is connected to the grinding section 110 at one end so that the central axis of the rod 120 and the center axis of the grinding section 110 coincide.

The drive unit 200 includes a grindstone rotating unit 210 that rotates around a rotation axis C. The other end of the rod 120 is attached to the grindstone rotating section 210 so as to be rotatable with respect to the driving section 200 so that the central axis of the rod 120 and the rotation axis C coincide. The grindstone rotating section 210 rotates the grinding section 110 by rotating the rod 120 around the rotation axis C-axis. Further, the drive unit 200 is configured to be movable in the vertical direction along the main body of the honing device 1000. The drive unit 200 moves the grinding unit 110 and the rod 120 in the vertical direction by moving in the vertical direction.

The control unit 300 is configured by a computer having a CPU and memory. The CPU of the control unit 300 controls the rotation and vertical movement of the drive unit 200 by executing a honing program stored in the memory in advance, and executes the honing process described below.

A2. Honing process:
The honing process of the present embodiment is performed to hone the inner circumferential surface of the bore portion Wb, whose surface roughness has increased due to deterioration over time, to a predetermined surface roughness. FIG. 2 is a flowchart showing the procedure of the first half of the honing process. FIG. 3 is a flowchart showing the procedure of the latter half of the honing process.

In step S110 of FIG. 2, the operator measures the surface roughness of the inner circumferential surface of the bore Wb and estimates the height Hp of the protrusion on the inner circumferential surface. In this embodiment, the worker measures the surface roughness using a stylus type surface roughness measuring device.

In step S120, the operator confirms the abrasive grain protrusion height Ha from the grindstone surface. The abrasive grain protrusion height Ha is estimated from the grindstone specifications such as the grain size of the abrasive grains.

In step S130, the operator determines the unit feed amount Fp, which is the amount of expansion of the rotation radius of the grindstone 112 per time. In this embodiment, when the protrusion height Hp is larger than the abrasive grain protrusion height Ha, the operator determines half of the abrasive grain protrusion height Ha as the unit feed amount Fp. Further, when the protrusion height Hp is less than or equal to the abrasive grain protrusion height Ha, the operator determines the abrasive grain protrusion height Ha as the unit feed amount Fp. Note that this step corresponds to the "first step" in the present disclosure.

In step S140, the operator determines a prescribed number of expansions Nf, which is the number of times Nf of expansion of the rotation radius of the grindstone 112 is necessary to scrape off the protrusion of the protrusion height Hp. The operator determines the specified number of expansions Nf based on the protrusion height Hp and the unit feed amount Fp. Specifically, for example, when the value obtained by dividing the protrusion height Hp by the unit feed amount Fp is 5.2, the prescribed number of expansions Nf is determined to be 6.

In step S150, the operator sets the rotation speed of the grindstone rotation unit 210 and the expansion speed when the rotation radius of the grindstone 112 is expanded by a fixed amount. The rotation speed and the expansion speed are determined by a known method depending on the grindstone 112 used, the material of the workpiece, etc.

In step S160, the operator operates the honing device 1000 to move the grinding section 110 into the bore section Wb, which is the processing position.

In step S170, the operator expands the grindstone 112 to bring it into contact with the inner circumferential surface of the bore Wb, and then retreats the expanded grindstone 112 a predetermined distance. In this embodiment, the operator expands the grindstone 112 by rotating the above-mentioned ball screw, and sets the point at which the expansion stops as the point of contact with the bore portion Wb.

In step S180, the operator activates the torque sensor of the honing device 1000 and starts collecting grinding load data. In this embodiment, the honing device 1000 uses a torque sensor to detect a voltage change of the motor that rotates the grindstone rotation unit 210 as a torque change, and records the change in the grinding load.

In step S190, the operator operates the honing device 1000 to start discharging the coolant and rotating the grindstone 112. In this embodiment, water-soluble cutting oil is used as the coolant. Further, the rotational speed of the grindstone 112 is determined depending on the size of the inner diameter of the bore portion Wb, the specifications of the grindstone 112 to be used, and the like.

In step S200, the operator performs a quantitative expansion step. The quantitative expansion step corresponds to the "second step" in the present disclosure. FIG. 4 is a flowchart showing the procedure of the quantitative expansion step.

In step S210, the operator sets the current number of extensions N to 0 and starts counting the number of extensions N.

In step S220, the operator operates the honing device 1000 to expand the expansion radius of the grindstone 112 by a unit feed amount Fp, and adds 1 to the number of expansions N (step S230).

If the number of expansions N is less than the specified number of expansions Nf (step S240: Yes), the operator waits until the grinding resistance decreases by a predetermined displacement width (step S250: No). The "predetermined displacement width" is set to a value by determining in advance the amount of reduction in grinding resistance when the protrusion is ground to a predetermined height through experiments or simulations.

If the grinding resistance is reduced by the predetermined displacement width (step S250: Yes), the operator executes step S220 again. The operator repeats the steps from step S220 to step S250 until the number of expansions N reaches the specified number of expansions Nf. When the number of expansions N reaches the specified number of expansions Nf (step S240: No), the operator ends the quantitative expansion process.

After the quantitative expansion process is finished, the operator finishes collecting the grinding resistance data in step S310 of FIG. 2.

In step S320, the operator records the expansion end position of the grindstone 112 at the end of the quantitative expansion process.

In step S330 of FIG. 3, the operator operates the honing device 1000 to stop the rotation of the grindstone and the coolant, contract the expanded grindstone 112, and retreat the grinding section 110 from the bore Wb.

In step S340, the operator visually checks the machined surface of the bore portion Wb, and determines whether the result of the visual check is good (step S350). The operator determines that the machined surface is good when visually confirming that there are no irregularities on the machined surface or when cross hatches are uniformly formed on the machined surface.

If the result of the visual confirmation is good (step S350: Yes), the operator measures the surface roughness of the machined surface of the bore portion Wb (step S360), and determines that the surface roughness is below a preset threshold. It is determined whether or not (step S370).

If the result of visual confirmation is not good (step S350: No), or if the surface roughness of the machined surface of the bore portion Wb is greater than the threshold value (step S370: No), the operator determines that additional honing is necessary. It is determined that there is, and the specified number of extensions Nf is determined anew (step S352).

In step S362, the operator operates the honing device 1000 to move the grinding section 110 into the bore section Wb, which is the processing position, again.

In step S372, the operator operates the honing device 1000 to expand the rotation radius of the grindstone 112 to the expansion end position at the end of the previous machining recorded in step S320. After that, the operator executes step S180 again. The operator repeatedly executes steps S180 to S370 until the surface roughness of the machined surface of the bore portion Wb becomes equal to or less than the threshold value in step S370. If the surface roughness of the machined surface of the bore portion Wb is less than or equal to the predetermined threshold (step S370: Yes), the operator ends the honing process.

According to the honing method described above, by expanding the rotation radius of the grindstone 112 in stages for each unit feed amount Fp, it is possible to gradually grind the convex portion on the inner peripheral surface of the bore portion Wb. Therefore, it is possible to suppress the occurrence of locally excessive grinding resistance, and the wear and tear of the grindstone 112 can be suppressed.

In addition, the operator increases the rotation radius of the grinding wheel 112 by the unit feed amount Fp every time the grinding resistance decreases by a predetermined displacement width, thereby suppressing a sudden increase in the grinding resistance and reducing wear and tear on the grinding wheel 112. It can be controlled more.

Further, when the surface roughness of the workpiece is larger than the abrasive grain protrusion height Ha, the operator sets a feed amount smaller than the abrasive grain protrusion height Ha as the unit feed amount Fp, so that the grinding wheel 112 The applied load can be further reduced, and wear and tear on the grindstone 112 can be further suppressed. On the other hand, when the surface roughness of the workpiece is less than or equal to the abrasive grain protrusion height, the unit feed amount Fp is set to the same feed amount as the abrasive grain protrusion height Ha, thereby suppressing a decrease in grinding efficiency. can.

B. Other Embodiments (B1) In the above embodiments, the honing process is performed to hone the inner circumferential surface of the bore portion Wb whose surface roughness has increased due to deterioration over time to a predetermined surface roughness. However, the present disclosure is not limited thereto. The honing process may be performed when the cylinder block W is manufactured.

(B2) In the above embodiment, when the protrusion height Hp is larger than the abrasive grain protrusion height Ha, the operator determines half of the abrasive grain protrusion height Ha as the unit feed amount Fp, but the present disclosure It is not limited to this. The operator may set the unit feed amount Fp of an arbitrary size smaller than the abrasive grain protrusion height Ha when the protrusion height Hp is larger than the abrasive grain protrusion height Ha. For example, the operator may determine 1/3 of the abrasive grain protrusion height Ha as the unit feed amount Fp.

(B3) In the embodiment described above, the honing device 1000 executes the quantitative expansion step described above in response to the operator's operation, but the present disclosure is not limited thereto. The honing device 1000 may automatically perform the quantitative expansion step by executing a program stored in the control unit 300 in advance. According to such a configuration, there is no need for operator operations in the quantitative expansion process, so it is possible to suppress a decrease in production efficiency.

(B4) In the above embodiment, the operator expands the rotation radius of the grindstone 112 every time the grinding resistance decreases by a predetermined displacement width, but the present disclosure is not limited thereto. The operator may expand the rotation radius of the grindstone 112 every time a predetermined period of time elapses.

(B5) In the above embodiment, when the surface roughness of the workpiece is larger than the abrasive grain protrusion height Ha, the operator determines a feed amount smaller than the abrasive grain protrusion height Ha as the unit feed amount Fp. However, when the surface roughness is less than or equal to the abrasive grain protrusion height Ha, a feed amount that is the same as the abrasive grain protrusion height Ha is determined as the unit feed amount Fp, but the present disclosure is not limited thereto. When the surface roughness of the workpiece is larger than the abrasive grain protrusion height Ha, the operator determines a feed amount that is the same as the abrasive grain protrusion height Ha as the unit feed amount Fp, and the surface roughness is When the abrasive grain protrusion height Ha is less than or equal to the abrasive grain protrusion height Ha, the feed amount may be determined as the unit feed amount Fp rather than the abrasive grain protrusion height Ha.

The present disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each form described in the summary column of the invention may be used to solve some or all of the above-mentioned problems, or to achieve one of the above-mentioned effects. In order to achieve some or all of the above, it is possible to replace or combine them as appropriate. Further, unless the technical feature is described as essential in this specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 100... Honing head, 110... Grinding part, 111... Head main body, 112... Grindstone, 120... Rod, 200... Drive part, 210... Grindstone rotation part, 300... Control part, 1000... Honing device, C... Rotating shaft, Fp ...unit feed amount, Ha...abrasive grain protrusion height, Hp...protrusion height, N...number of expansions, Nf...specified number of expansions, W...cylinder block, Wb...bore part

Claims (3)

A honing method,
A first step of determining the unit feed amount based on the surface roughness of the inner circumferential surface of the workpiece and the protrusion height of the abrasive grains in the grindstone used while attached to the honing head;
The rotation of the grindstone is started from a state where the grindstone and the workpiece are not in contact with each other, and the rotation radius of the grindstone is expanded stepwise for each unit feed amount according to a change in grinding resistance. a second step of processing the workpiece;
Equipped with
Honing method. The honing method according to claim 1,
The second step includes a step of expanding the rotation radius by the unit feed amount each time the grinding resistance decreases by a predetermined displacement width.
Honing method. The honing method according to claim 1 or 2,
In the first step, when the surface roughness is larger than the protrusion height, a feed amount smaller than the protrusion height is determined as the unit feed amount, and when the surface roughness is equal to or less than the protrusion height, , including the step of determining a feed amount that is the same as the protrusion height as the unit feed amount;
Honing method.

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