JPH0428482B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bearing hole profiling device for machining a piston pin hole or the like of an internal combustion engine into a special shape.

The pin hole in the piston of an internal combustion engine is subjected to extremely high pressure during an engine explosion. Particularly with high-load pistons, cracks often occur near the upper end of the inside of the pin hole. is strongly pressed and a strong stress concentration occurs, and as a result, the pin is crushed in the direction of piston movement, and as a result, the pin expands the pin hole, and tensile stress is generated at the upper end inside the pin hole.

Therefore, in order to alleviate the high stress mentioned above,
For example, the pin hole expands very slightly toward the center of the piston, and even if the piston pin is bent or crushed, the local stress concentration when the pin is pressed against the pin hole is relaxed and leveled out, and the pin hole expands slightly toward the center of the piston. However, bearing holes with high surface pressure such as piston pin holes require high precision and a specified surface roughness, and must be machined at low cost. Therefore, the above method was not used.

In other words, since the amount by which the pin hole expands inward is extremely small, equivalent to the amount by which the pin is crushed, it is difficult to process it using a numerical control device, etc. It was impossible to carry out finishing operations.

Conventionally, measures have been taken to solve these problems, such as increasing the diameter of the piston pin or reducing the dimension between the piston bosses. There were problems in that the weight of the stove increased, the shape of the stove rod had to be changed, and the cost also increased.

The present invention has been made based on the above-mentioned viewpoints, and an object of the present invention is to form a pin hole with a high taper so that the taper amount changes continuously as the pin hole approaches the center of the piston. It is an object of the present invention to provide a bearing hole copy processing device that can process a bearing hole with high accuracy and a predetermined surface roughness at a low cost.

Therefore, the gist of the present invention is as follows.
The components described in (a) to (g), namely (a) a rotatably supported main shaft, and (b) a slit attached to the main shaft coaxially with the rotation axis and formed inside. The area is divided into an area for attaching to the main shaft and an area for attaching the boring tool, and both areas are connected by an area having a spring force, and an external force approximately perpendicular to the axis is applied to the attaching area of the boring tool. (c) an eccentric device configured such that when the spring force is applied, the mounting side region of the boring tool is eccentricized against the spring force, and a restoring force is generated in the axial direction by the spring force; (d) A stylus guide is formed on the inner circumferential surface according to the machining shape, and the boring tool is substantially co-located with the boring tool attached to the outer end of the boring tool attachment side area of the eccentric device. A cylindrical master cam is inserted through the shaft and rotatably supported separately from the main shaft, and (e) the tip of the master cam is brought into contact with the stylus guide of the master cam, and the boring tool is (f) a stylus fixed to the boring tool so that the boring tool attachment side area of the eccentric device is eccentrically set according to the shape of the inner peripheral surface of the stylus guide; and (f) moving relative to the main shaft in the direction of the main shaft. The machine is characterized by comprising a workpiece stand which is freely supported and to which a workpiece is attached, and (g) a processing feed device that moves the main spindle relative to the workpiece stand and the master cam in the direction of the main axis. There is a bearing hole profiling machine.

Hereinafter, the details of the present invention will be specifically explained with reference to the drawings.

The drawing is an explanatory view showing an embodiment of a bearing hole copying device according to the present invention.

In the figure, 1 is a main shaft that is rotatably supported so as to move forward and backward in the direction of the rotation axis, 2 is an eccentric device attached to the main shaft 1, 2a is a slit formed in the eccentric device 2, and 3 is a boring hole. 4 is a tool attached to the tip of the boring tool 3; 5 is a master cam supported approximately concentrically with the boring tool 3; 6 is a master cam holder;
7 is a bearing; 8 is a master cam holder that holds the master cam 5 including the bearing 7 and the master cam holder 6, and is fixed to the slide base or movably mounted on the slide base;
9 is a stylus whose tip is pressed against the master cam 5; 10 is a bolt for attaching the boring tool 3 to the eccentric device 2; 11 is a workpiece; 11a
1 is a piston pin hole, and 12 is a workpiece table.

An eccentric device 2 is attached to the rotatably supported main shaft 1, and a boring tool 3 having a cutting tool 4 and a stylus 9 attached to its tip is attached to the eccentric device 2 by a bolt 10. It is being

A slit 2a is formed in the eccentric device 2, and the boring tool 3 is configured to be eccentric while keeping the center of the boring tool 3 parallel to the main axis at all times.

That is, the eccentric device 2 is divided into a main shaft mounting region 2b and a boring tool mounting region 2c by a slit 2a formed inside the eccentric device 2, and both are connected by a region 2d having a spring force. When an external force substantially perpendicular to the axis is applied to the mounting area 2c of the boring tool, the mounting area 2c of the boring tool is eccentrically moved against the spring force and restored in the axial direction by the spring force. Since the stylus 9 is configured to generate a force, the stylus 9 is pressed against the stylus guide 5a on the inner circumferential surface of the master cam 5 by the restoring force in the axial direction due to the spring force, and is immediately affected by the change in the shape of the stylus guide 5a. Correspondingly, it moves eccentrically. Such an eccentric device 2
is a region 2b on the attachment side to the main shaft, a region 2c on the attachment side of the boring tool, and a region 2d having a spring force that connects the two (which may be integrally formed of the same material as the regions 2b and 2c, or (The region 2d portion may be formed by a leaf spring.)
Since the structure is simple, the cost is low and there are few causes of failure.

A master cam 5 is attached to the master cam holder 6 and has the same taper shape (single or continuously changing taper) on its inner peripheral surface as the piston pin hole 11a formed in the workpiece 11. Since this master cam holder 6 is held via a bearing 7, it can freely rotate around the central axis of rotation of the boring tool 3.

Thus, the boring tool 3 attached to the eccentric device 2 rotates as the main shaft 1 rotates,
Further, it is moved toward the workpiece 11 along the central axis of the main spindle 1 by a processing feed device (not shown).

When the stylus 9 reaches the master cam 5, the stylus 9 rotates while contacting the inner peripheral wall of the master cam 5 with appropriate contact pressure, but the stylus 9 and the cutting tool 4 are the same boring tool. 3, so if the stylus 9 is eccentric according to the shape of the master cam 5, the cutting tool 4 will also be eccentric by the same amount, so a piston pin hole 11a corresponding to the shape of the master cam 5 is machined in the workpiece 11. be done.

Furthermore, the master cam 5 has a master cam holder 6.
Since it is rotatably supported by the bearing 7 via the master cam 5 and the stylus 9, it can freely rotate due to the frictional force between the master cam 5 and the stylus 9. For this reason, the contact pressure of the stylus 9 against the master cam 5 is increased by adjusting the size of the slit 2a provided in the eccentric device 2, and the stylus 9 is constantly pressed against the master cam 5 during machining to prevent vibrations (chatter) etc. The master cam 5 rotates in response to the contact pressure of the stylus 9, and the stylus 9 slides on the master cam 5 only in the direction of movement of the slide base. As a result, there is less wear on the tip of the stylus 9, and machining can be performed with stable accuracy for a long time.

Therefore, if the cutting tool 4 attached to the tip of the boring tool 3 is attached on the outer circumference of the boring tool 3 so as to be in the same radial direction as the stylus 9, the inner diameter of the stylus guide 5a on the inner surface of the master cam 5 is increased. So stylus 9
is pushed upward in the figure by the eccentric device 2. By this, the bite 4 and the stylus 9
Since the piston pin hole 11a is pushed up by the same amount as the stylus guide 5a, the piston pin hole 11a has to be machined larger.On the other hand, at the point where the inner diameter of the stylus guide 5a has become smaller, the stylus 9 is pushed down, so the piston pin hole 11a has to be machined larger. 11a will be processed into a smaller size.

That is, due to this amount of eccentricity, the stylus 9 contacts the inner circumferential wall surface of the master cam 5 with an appropriate contact pressure, and the cutting tool 4 moves according to the shape of the master cam 5, so that the piston pin hole 11a corresponds to the shape of the master cam 5. is formed.

Since the present invention is configured as described above, when using the bearing hole copy processing apparatus according to the present invention, bearing holes of special shapes such as piston pin holes can be processed with high accuracy and a predetermined surface roughness, and at low cost. It is possible to do so.

Note that the present invention is not limited to the above embodiments. That is, for example, in this embodiment, the master cam had a cylindrical shape, but it may have another shape such as a frame shape, and a slit may be provided in the portion corresponding to the cylindrical master cam to allow the stylus to The slide base may be moved in the moving direction of the slide base while contacting the bottom surface of the slit, and the bottom surface of the slit may be shaped in accordance with the degree of taper of the piston pin hole shape. In this case, the stylus is caught on the side surface of the slit, causing the master cam holder to rotate. In addition, in this example, the cutting tool and the stylus were in the same radial direction of the boring tool, but they were in opposite directions (180 degrees) on the same straight line.
It's okay to be there. In this case, the taper shape of the master cam is opposite to that of the pin hole. Furthermore, it is also possible to configure the main shaft etc. to only rotate and not move, but to move the workpiece table and the master cam holder. The design, such as the mounting position, can be freely changed within the scope of the object of the present invention, and the present invention encompasses all of them.

[Brief explanation of drawings]

The drawing is an explanatory view showing an embodiment of a bearing hole copying device according to the present invention. 1... Main shaft, 2... Eccentric device, 3... Boring tool, 4... Bit, 5... Master cam, 6
...Master cam holder, 7...Bearing, 8...
... Master cam type holder, 9 ... Stylus, 10
... Bolt, 11 ... Workpiece, 11a ... Piston pin hole, 12 ... Workpiece table.

Claims (1)

[Scope of Claims] 1. A bearing hole profiling device characterized by comprising the components described in items (a) to (g) below. (a) Spindle 1 rotatably supported. (b) It is attached to the spindle 1 coaxially with its rotation axis, and is divided into a spindle attachment side area 2b and a boring tool attachment side area 2c by a slit 2a formed inside, and both of the above areas are They are connected by a region 2d having a spring force, and when an external force substantially perpendicular to the axis is applied to the mounting region 2c of the boring tool, the mounting region 2c of the boring tool is eccentrically moved against the spring force. The eccentric device 2 is configured to generate a restoring force in the axial direction by the spring force. (c) A boring tool 3 having a cutting tool 4 at its tip and attached to the outer end of the boring tool attachment area 2c of the eccentric device 2. (d) A stylus guide 5a is formed on the inner circumferential surface according to the machining shape, and the boring tool 3 is inserted into the stylus guide 5a substantially coaxially with the stylus guide 5a, and is rotatably supported separately from the main shaft 1. A cylindrical master cam 5. (e) The tip is brought into contact with the stylus guide 5a of the master cam 5, and due to the contact pressure, the boring tool attachment side area 2c of the eccentric device is moved through the boring tool 3 according to the shape of the inner circumferential surface of the stylus guide 5a. A stylus 9 is fixed to the boring tool 3 so as to be eccentric. (f) A workpiece table 12 supported so as to be movable relative to the main shaft 1 in the direction of the main shaft, and on which the workpiece 11 is mounted. (g) A processing feed device that moves the main spindle 1 relative to the workpiece stand 12 and master cam 5 in the main axis direction.