JP7500201B2 - Honing device and processing method using same - Google Patents

Description

The present invention relates to a honing device for machining the inner cylindrical surface of a workpiece and a machining method using the same.

Conventionally, in cylindrical machining areas formed on workpieces that require high-precision machining, such as cylinder blocks for reciprocating engines mounted on automobiles, compressor bearings and hydraulic parts, and fuel injection nozzles, the cylindrical inner surface has been subjected to cutting and grinding processes, and then finished using a honing device.

In finishing processing using a honing device, the roundness and cylindricity of the cylinder's inner surface are improved, and crosshatching (intersecting grooves or striations) is formed on the cylinder's inner surface as an oil reservoir to retain lubricating oil. The crosshatching is formed by rotating the honing stone that is inserted into the cylinder's inner surface around the axis while moving it back and forth in the axial direction.

Patent No. 5679544

When the honing device moves back and forth in the axial direction, for example, when the direction of movement is changed, such as from rising to falling or from falling to rising, the device is decelerated from a constant speed, stopped, the direction of movement is changed, and then accelerated back to a constant speed. In conventional honing devices, the problem was that such deceleration and acceleration caused crosshatch M' with a curved shape to be formed on the inner surface of the cylinder in the area where the grinding wheel Z abuts during deceleration and acceleration, as shown in Figure 6. Such irregular crosshatch M' is formed in large amounts near the axial end and becomes less frequent as it approaches the axial center, and is not formed at approximately the axial center where the grinding wheel Z moves at an approximately constant speed. Note that Figure 6 is a schematic diagram of the cylindrical inner surface of the workpiece W' on which crosshatch M' is formed, expanded in the circumferential direction.

In order to deal with the formation of crosshatch M' with irregular shapes near the axial end of the workpiece, the acceleration and deceleration times were shortened, but even so, the axial dimension of the curved part of the crosshatch M' can range from several mm to several tens of mm, so this was not a sufficient solution.

A grinding device such as that disclosed in Patent Document 1 has also been proposed. The grinding device in Patent Document 1 is described as being able to make the cross-hatch line intersection angle constant over the entire machining area of the workpiece by setting the rotational speed of the grinding wheel, which is reciprocated by a reciprocating mechanism, to zero at the turning points (top dead center, bottom dead center) and synchronizing the reciprocating movement speed and rotational speed of the grinding wheel.

However, the grinding device of the above-mentioned conventional patent document 1 requires a large motor to be installed in order to slow down, stop, and accelerate the rotation speed in accordance with changes in the moving speed of the grinding wheel, and consumes a lot of power. In addition, there is a risk of abnormal wear of the grinding wheel at the axial end of the workpiece, or of abnormal cutting into the workpiece.

The present invention was made in consideration of these points, and its purpose is to easily control the formation of crosshatching without making major modifications to existing honing equipment.

To achieve the above objective, this invention controls the formation of crosshatching with a simple configuration by synchronizing the reciprocating speed of the honing tool with the control of the radial advancement and retreat of the grinding wheel, thereby preventing crosshatching from forming at the axial end of the workpiece.

Specifically, in the first invention,
A honing device for machining a cylindrical inner surface formed on a workpiece by a honing tool having a rotating shaft and a grindstone that moves radially forward and backward relative to the rotating shaft,
A rotation mechanism that rotates the rotation shaft;
A reciprocating mechanism for reciprocating the honing tool in an axial direction;
a grindstone control mechanism for moving the grindstone radially forward and backward;
The grindstone control mechanism controls the speed of movement of the honing tool in the axial direction by the reciprocating movement mechanism.
When the target speed is reached, the grindstone is pushed outward in the radial direction to bring the inner surface of the cylinder into contact with the grindstone,
After the contact state is reached, the grinding wheel is pulled radially inward when the speed is reduced from the target speed, thereby bringing the cylindrical inner surface and the grinding wheel into a non-contact state.

In the first invention, the formation of crosshatch can be controlled by synchronizing the speed of the axial reciprocating movement of the honing tool with the control of the radial advancement and retreat of the grinding wheel. Note that the crosshatch here refers to fine scratches (grooves, stripes, etc.) that intersect in a mesh pattern on the cylindrical inner surface of the workpiece to retain lubricant, and the axial direction is the direction parallel to the extension of the rotation axis.

Specifically, the axial movement speed of the honing tool gradually increases, and when it reaches the target speed, the grindstone control mechanism pushes the grindstone radially outward, so that the cylinder inner surface and the grindstone come into contact with each other. Then, as the honing tool continues to move in the axial direction while remaining in this state, the grindstone forms linear streaks on the cylinder inner surface that become part of the crosshatch. Then, as the honing tool switches its movement direction, for example, from rising to falling or from falling to rising, the movement speed gradually decreases, and when it is decelerated from the target speed, the grindstone control mechanism pulls the grindstone radially inward, so that the cylinder inner surface and the grindstone come into a non-contact state. Since the honing tool switches its movement direction while remaining in this state, no curved streaks are formed on the cylinder inner surface before and after the change in movement direction. Then, as the movement speed gradually increases when moving in the opposite direction, and when it reaches the target speed, the grindstone control mechanism pushes the grindstone radially outward again, so that the cylinder inner surface and the grindstone come into contact with each other. As the honing tool continues to move in the axial direction in this state, the grindstone further forms linear marks on the inner surface of the cylinder that become part of the crosshatch. As a result, no curved marks are formed when the honing tool changes direction of movement, and no disturbed parts of the crosshatch are formed. In this way, the formation of the crosshatch can be controlled with a simple configuration, which contributes to the miniaturization and cost reduction of honing equipment.

In addition, by controlling the grindstone by changing the movement speed when the direction of reciprocating movement is switched, honing can be performed at the optimum processing speed, preventing abnormal wear of the grindstone at the axial end of the workpiece and abnormal cutting into the workpiece.

In a second aspect of the present invention, in the first aspect,
The rotating mechanism is characterized in that it keeps the rotational speed of the rotating shaft constant while the honing tool reciprocates during machining of the workpiece.

In this second invention, the range in which the crosshatch is formed can be controlled without changing the rotation speed, so there is no need to install a large motor as in the past, and power consumption can be reduced compared to the past.

In a third aspect of the present invention, in the first or second aspect of the present invention,
When the honing tool reaches a predetermined position by the movement in the axial direction, the grindstone control mechanism drives the grindstone to move forward and backward.

This third invention is more useful because it allows the crosshatch formation range to be controlled by the position of the honing tool without requiring major modifications to existing honing equipment.

In a fourth aspect of the present invention, any one of the first to third aspects of the present invention is used,
The honing tool, in which the cylindrical inner surface and the grindstone are in contact with each other on the cylindrical inner surface, is moved in an axial direction toward an axial end of the workpiece;
Before the honing tool reaches the axial end of the workpiece, the moving speed of the honing tool is decelerated, and when the moving speed of the honing tool is decelerated below the target speed, the grindstone control mechanism is driven to bring the cylindrical inner surface and the grindstone into a non-contact state;
When the honing tool reaches the axial end of the workpiece in the non-contact state and the moving speed becomes zero, the moving direction is switched, the moving speed of the honing tool is accelerated, and when the moving speed again reaches the target speed, the grindstone control mechanism is driven to bring the cylindrical inner surface and the grindstone into contact with each other.

In this fourth invention, the grindstone is retracted before the honing tool reaches the axial end, and then pushed out again after the direction of movement is changed, making it possible to more reliably prevent abnormal wear of the grindstone at the axial end of the workpiece and abnormal cutting into the workpiece.

As described above, according to the present invention, by synchronizing the reciprocating speed of the honing tool with the control of the radial advance and retreat of the grinding wheel, it is possible to control the formation of crosshatch with a simple configuration, which contributes to the miniaturization and cost reduction of honing processing equipment.

1 is a schematic perspective view of a honing device according to an embodiment of the present invention. FIG. FIG. 2 is a schematic cross-sectional view for explaining the advancement and retreat of a grindstone of the honing device according to the embodiment of the present invention. 5 is a timing chart showing the relationship between the advancement/retraction and rotation speed of the grindstone and the moving speed of the honing tool. FIG. 2 is a schematic diagram showing an expanded cylindrical inner surface of a workpiece on which crosshatching has been formed by the honing device according to the embodiment of the present invention. 5A to 5C are schematic diagrams for explaining the movement of a grindstone on a cylindrical inner surface according to an embodiment of the present invention. 1 is a schematic diagram showing an expanded cylindrical inner surface of a workpiece on which crosshatching has been formed by a conventional honing device. FIG.

The following describes in detail the embodiments of the present invention with reference to the drawings. The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the present invention, its applications, or its uses.

In the following description, the direction parallel to the direction in which the rotation axis of the honing tool extends is referred to as the "axial direction," and the radial direction centered on the rotation axis is referred to as the "radial direction." Furthermore, the axial direction is the up-down direction, and the upper side of the drawing is simply referred to as the "upper side," and the lower side is simply referred to as the "lower side." The reciprocating movement speed of the honing tool is simply referred to as the "moving speed."

The workpiece W, which is the object to be machined by the honing device 1 of the present invention, has a cylindrical machining portion formed thereon, and the honing device 1 of the present invention machines the cylindrical inner surface W1 of the machining portion.

As shown in FIG. 1, the honing device 1 includes a rectangular parallelepiped bed 2 and a rectangular parallelepiped column 3 erected on the rear side of the bed 2, and the bed 2 and column 3 are configured to form a roughly L-shape when viewed from the side.

The honing device 1 also includes a processing section 4 that is provided in front of the column 3 and processes the cylindrical inner surface W1 of the workpiece W, and a workpiece support section 5 that is installed on the bed 2 and supports the workpiece W.

Next, the detailed structure of the honing device 1 will be described below.

The workpiece support section 5 has a worktable 52 fixed to the upper surface side of the bed 2, and a holding stand 53 for holding the workpiece W on the upper surface side of the worktable 52. The central axis of the workpiece W is held so as to extend in a direction (axial direction) parallel to the direction in which the rotation axis 74 of the honing tool 70 extends.

The processing section 4 has a tool table 41 fixed to the front side of the column 3, and the tool table 41 is provided with a honing processing unit 7.

The honing unit 7 comprises a rectangular honing body 71 attached to the front side of the tool table 41, a honing support 72 attached to the front side of the honing body 71, a support shaft 73 extending vertically within the honing support 72, and a honing tool 70 attached to the lower part of the support shaft 73.

The honing tool 70 has a rotating shaft 74 and a grindstone 75 attached below the rotating shaft 74. The grindstone 75 rotates together with the rotating shaft 74 and moves forward and backward radially relative to the rotating shaft 74.

The honing device 1 includes a rotation mechanism 7a that rotates the rotation shaft 74 of the honing tool 70. The rotation mechanism 7a is disposed in the honing main body 71 and includes a transmission belt (not shown) that transmits rotational force to the honing tool 70, and a rotation drive motor (not shown) that rotates the honing tool 70 around the rotation shaft 74 via the transmission belt.

The honing device 1 also includes a reciprocating mechanism 7b that reciprocates the honing tool 70 in the axial direction. The reciprocating mechanism 7b reciprocates the rotating shaft 74 and grindstone 75 in the vertical direction (axial direction) to form a mesh-like crosshatch M that functions as an oil reservoir for the lubricating oil on the cylindrical inner surface W1 of the workpiece W. Specifically, the reciprocating mechanism 7b includes a reciprocating motor 81 that reciprocates the honing support part 72 in the axial direction relative to the honing main body part 71, a slide rail 82 provided on the front side of the honing main body part 71, and a slide receiving part 83 that is provided on the honing support part 72 and slides while being guided by the slide rail 82.

The honing device 1 further includes a grindstone control mechanism 7c that moves the grindstone 75 forward and backward in the radial direction. The grindstone control mechanism 7c is disposed on the support shaft 73. As will be described in detail later, the grindstone control mechanism 7c has a drive shaft adjustment motor (not shown), which raises and lowers the drive shaft 76 of the honing tool 70 and adjusts the amount of vertical movement of the tapered portion 77, thereby moving the grindstone 75 forward and backward in the radial direction.

The grindstone control mechanism 7c is configured to bring the cylindrical inner surface W1 and the grindstone 75 into contact with each other by pushing the grindstone 75 outward in the radial direction when the axial movement speed of the honing tool 70 by the reciprocating movement mechanism 7b reaches the target speed Q, and to bring the cylindrical inner surface W1 and the grindstone 75 into a non-contact state by pulling the grindstone 75 inward in the radial direction when the speed is decelerated from the target speed Q after the contact state is reached.

The control device 58 disposed inside the bed 2 controls the operation of various devices of the honing device 1, and in this embodiment, is configured to control, for example, the rotary drive motor constituting the rotation mechanism 7a, the reciprocating motor 81 that moves the honing support part 72 back and forth in the axial direction, and the drive shaft adjustment motor that moves the grinding wheel 75 back and forth in the radial direction.

Next, the detailed structure of the honing unit 7 will be explained with reference to Figure 2.

A holding frame 79 is formed integrally with the rotating shaft 74 and extends in the axial direction at the lower end of the rotating shaft 74, and a slit 79a extending in the axial direction is formed in the lower part of the holding frame 79. The grindstone 75 is attached so that it can move in and out of this slit 79a.

The rotating shaft 74 and the holding frame 79 are cylindrical, and a drive shaft 76 that can slide in the axial direction by, for example, NC control or hydraulic pressure is provided inside. The lower part of the drive shaft 76 has two conical tapered sections 77 that narrow in diameter toward the bottom.

At least one grindstone 75 is provided in the circumferential direction of the rotating shaft 74, and multiple grindstones 75 are arranged, for example, at equal intervals. The grindstone 75 also has a tapered surface 75a that can contact the tapered surface 77a of the tapered portion 77 of the drive shaft 76. The grindstone 75 moves in and out of a slit 79a formed in the holding frame 79, thereby moving forward and backward radially relative to the rotating shaft 74.

Specifically, as the tapered portion 77 (drive shaft 76) slides downward, the grindstone 75 in contact with the tapered portion 77 is pushed outward in the radial direction, and the diameter of the honing tool 70 is expanded. As the tapered portion 77 slides upward, the grindstone 75 in contact with the tapered portion 77 is pulled inward in the radial direction, and the diameter of the honing tool 70 is reduced and returned to its original diameter. When honing the workpiece W, the honing grindstone 75 of the honing tool 70 that has entered the cylinder of the workpiece W jumps out of the slit 79a, i.e., the grindstone 75 expands and comes into contact with the cylindrical inner surface W1 of the workpiece W, and the workpiece W rotates, allowing the honing process to be performed.

Next, the procedure for forming the crosshatch M on the cylindrical inner surface W1 of the workpiece W will be described with reference to Figures 3 to 5. Note that Figure 3 is a timing chart showing the relationship between the advancement and retreat of the grindstone and the rotation speed and the movement speed of the honing tool when forming the crosshatch, and the position of 0 on the horizontal axis (time axis) corresponds to the state where the grindstone 75 is at position Z1 in Figure 5.

First, the rotation drive motor (not shown) of the rotation mechanism 7a is operated to rotate the rotation shaft 74 at a predetermined rotation speed R. The rotation mechanism 7a keeps the rotation speed of the rotation shaft 74 constant while the honing tool 70 moves back and forth during machining of the workpiece W.

Then, when the reciprocating motor 81 is operated, the movement speed gradually accelerates, and the slide receiving portion 83 on the honing support portion 72 is guided by the slide rail 82 on the honing main body portion 71, and the honing support portion 72, the rotating shaft 74, and the grindstone 75 move axially downward so as to approach the workpiece W. At this time, the grindstone 75 is retracted radially inward.

Then, when the grindstone 75 enters the cylindrical inner surface W1 of the workpiece W and the moving speed reaches a predetermined target speed Q, the drive shaft adjustment motor (not shown) of the grindstone control mechanism 7c is activated and the drive shaft 76 slides downward. At this time, the grindstone 75 is pushed outward in the radial direction, expanding its diameter, and the cylindrical inner surface W1 and the grindstone 75 come into contact. At this time, the grindstone 75 is in position Z1 in FIG. 5.

The honing tool 70, whose cylindrical inner surface W1 is in contact with the grindstone 75, is raised toward the axial end of the workpiece W at a constant speed equal to or greater than the target speed Q by the operation of the reciprocating motor 81. That is, in FIG. 5, the grindstone 75 moves from Z1 to Z2. As a result, linear striations in the X direction that are part of the crosshatch M are formed on the cylindrical inner surface W1 of the workpiece W, as shown in FIG. 4.

Next, the moving speed of the honing tool 70 is decelerated before it reaches the axial end W2 of the workpiece W. Then, when the moving speed is decelerated below the target speed Q, the grindstone control mechanism 7c is driven and the drive shaft 76 slides axially upward. At this time, the grindstone 75 is pulled radially inward, reducing its diameter, and the cylindrical inner surface W1 and the grindstone 75 are no longer in contact with each other.

In this non-contact state, the honing tool 70 reaches the axial end W2 of the workpiece, i.e., in FIG. 5, the grindstone 75 moves from Z2 to Z3, and after the moving speed becomes zero, the moving direction switches from upward to downward. Then, the moving speed of the honing tool 70 accelerates, and when it reaches the target speed Q again while descending, the grindstone control mechanism 7c is driven and the cylindrical inner surface W1 and the grindstone 75 come into contact again (from Z3 to Z4 in FIG. 5).

While maintaining this contact state, the reciprocating motor 81 is operated to lower the workpiece W toward the axial end W3 at a constant speed equal to or greater than the target speed Q. In other words, the workpiece W moves from Z4 to Z5 in FIG. 5. This forms linear streaks in the Y direction, which are part of the crosshatch M, on the cylindrical inner surface W1 of the workpiece W.

Then, the moving speed of the honing tool 70 is decelerated before it reaches the axial end W3 of the workpiece W. Then, when the moving speed is decelerated below the target speed Q, the grindstone control mechanism 7c is driven, the grindstone 75 is pulled radially inward, reducing its diameter, and the cylindrical inner surface W1 and the grindstone 75 are no longer in contact with each other (from Z5 to Z6 in FIG. 5).

The reciprocating movement of the honing tool 70 may be controlled by NC control. Specifically, when the honing tool 70 reaches a predetermined position by axial movement, the grindstone control mechanism 7c drives the grindstone 75 to move forward and backward, allowing the range of crosshatch M to be controlled with greater precision.

In this case, for example, the acceleration/deceleration distance S (mm) can be calculated from the acceleration/deceleration time constant t (sec) and the speed v (m/sec) as shown in Equation 1:
S = v × t × 1000 ... (Equation 1)
At the moment when it reaches S mm before the stopping position, the grindstone control mechanism 7c is driven to put the cylindrical inner surface W1 and the grindstone 75 into a non-contact state, and after stopping, the movement direction is changed and the grindstone control mechanism 7c is driven to control so that the cylindrical inner surface W1 and the grindstone 75 are again in contact with each other.

In this manner, according to the present embodiment, the formation of the crosshatch M can be easily controlled by synchronizing the reciprocating movement speed of the honing tool 70 with the radial advance/retract control of the grindstone 75. Specifically, the axial movement speed of the honing tool 70 gradually increases, and when it reaches the target speed Q, the grindstone control mechanism 7c pushes the grindstone 75 radially outward, so that the cylindrical inner surface W1 and the grindstone 75 come into contact with each other. Then, as the honing tool 70 continues to move in the axial direction at a constant speed while maintaining that state, linear streaks that become part of the crosshatch M are formed on the cylindrical inner surface W1. Then, when the honing tool 70 gradually decreases in movement speed to switch the movement direction, for example, from rising to falling or from falling to rising, and is decelerated from the target speed Q, the grindstone control mechanism 7c pulls the grindstone 75 radially inward, so that the cylindrical inner surface W1 and the grindstone 75 come into a non-contact state. Since the honing tool 70 switches the moving direction while remaining in this state, no curved streaks are formed on the cylindrical inner surface W1 before and after the switching of the moving direction. Then, when the moving speed gradually increases while moving in the opposite direction, the grindstone control mechanism 7c pushes the grindstone 75 outward in the radial direction again when it reaches the target speed Q, so that the cylindrical inner surface W1 and the grindstone 75 come into contact with each other. As the honing tool 70 continues to move in the axial direction at a constant speed while remaining in this state, linear streaks that become part of the crosshatch M are further formed on the cylindrical inner surface W1. As a result, the crosshatch M is not formed when the moving direction of the honing tool 70 is switched, and therefore no disturbed portion of the crosshatch M is formed. Since the formation of the crosshatch M can be controlled with a simple configuration, this contributes to the miniaturization and cost reduction of the honing processing device 1.

Furthermore, when the direction of reciprocating movement is switched, the grindstone 75 can be controlled by changing the movement speed, allowing processing to be performed at the optimum processing speed for honing, preventing abnormal wear of the grindstone 75 at the axial ends W2, W3 of the workpiece W and abnormal cutting into the workpiece W.

Furthermore, since the range in which the crosshatch M is formed can be controlled without changing the rotational speed of the rotating shaft 74 during processing, there is no need to install a large motor as in the past, and power consumption can be reduced compared to the past.
Other Embodiments
In this embodiment, the axial direction is the up-down direction, but is not limited to this. Also, the crosshatch M formed on the cylindrical inner surface of the work W is not limited to the pattern shown in Fig. 4, and the interval, inclination angle, depth, width, etc. may be appropriately set in consideration of the size of the work W and the function of retaining the lubricating oil.

In addition, in this embodiment, the rotation mechanism 7a and the reciprocating motor 81 are disposed in the honing main body 71, the grindstone control mechanism 7c is disposed in the support shaft 73, and the control device 58 is disposed inside the bed 2, but the locations where these are disposed are not limited to these.

In addition, in this embodiment, a rotary drive motor for the rotary mechanism 7a, a reciprocating motor 81 for the reciprocating mechanism 7b, and a drive shaft adjustment motor for the grindstone control mechanism 7c are provided, but they are not limited to motors as long as they fulfill the function of operating each of them.

The rotation of the rotating shaft 74 may begin after the grinding wheel 75 has entered the cylindrical inner surface W1 or while it is entering the cylindrical inner surface W1.

Reference Signs List 1 Honing device 7a Rotation mechanism 7b Reciprocating mechanism 7c Grindstone control mechanism 70 Honing tool 74 Rotation shaft 75 Grindstone M Cross hatch Q Target speed W Workpiece W1 Cylindrical inner surface W2 Axial end W3 Axial end

Claims (2)

A honing device for machining a cylindrical inner surface formed on a workpiece by a honing tool having a rotating shaft and a grindstone that moves radially forward and backward relative to the rotating shaft,
A rotation mechanism that rotates the rotation shaft;
A reciprocating mechanism for reciprocating the honing tool in an axial direction;
a grindstone control mechanism for moving the grindstone forward and backward in a radial direction;
The grindstone control mechanism controls the speed of movement of the honing tool in the axial direction by the reciprocating movement mechanism.
When the target speed is reached, the grindstone is pushed outward in the radial direction to bring the inner surface of the cylinder into contact with the grindstone;
After the contact state is established, when the speed is decelerated from the target speed, the grindstone is pulled inward in the radial direction to bring the cylindrical inner surface and the grindstone into a non-contact state;
A honing device configured such that the grindstone is advanced and retreated while the moving speed of the honing tool is changed. A step of preparing a honing device including a honing tool having a rotating shaft and a grindstone which moves radially forward and backward with respect to the rotating shaft and which processes a cylindrical inner surface formed on a workpiece, a rotation mechanism which rotates and drives the rotating shaft, a reciprocating mechanism which moves the honing tool back and forth in the axial direction, and a grindstone control mechanism which moves the grindstone forward and backward in the radial direction;
A step of moving the honing tool, with the cylindrical inner surface and the grindstone in contact with each other on the cylindrical inner surface, in an axial direction toward an axial end of the workpiece;
a step of decelerating the moving speed of the honing tool before the honing tool reaches an axial end of the workpiece, and when the moving speed of the honing tool is decelerated below a target speed, the grindstone control mechanism is driven to bring the cylindrical inner surface and the grindstone into a non-contact state;
a step of: after the honing tool reaches an axial end of the workpiece in the non-contact state and the moving speed becomes zero, the moving direction is switched, the moving speed of the honing tool is accelerated, and when the moving speed again reaches the target speed, the grindstone control mechanism is driven to bring the cylindrical inner surface and the grindstone into contact with each other;
A processing method using a honing device, characterized in that the grindstone is advanced and retreated while the moving speed of the honing tool is changed.

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