JPH0474094B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to an engine cylinder sleeve port machining device that punches and forms scavenging or exhaust ports in a cylinder sleeve that forms a cylinder hole of a two-stroke engine. .

[Conventional technology]

Conventionally, in cylinders used in high-output engines such as motorcycles, cylinder sleeves made of high-phosphorus cast iron that are centrifugally cast are press-fitted into cylinder bodies made of aluminum, or cylinder sleeves are cast-in by casting. It is not easy to form the necessary ventilation ports for intake, scavenging, and exhaust in the cylinder sleeve, and it has been difficult to obtain high precision.

[Problems to be solved by the invention]

In other words, the general method for forming port holes is to simultaneously form them by casting during the casting of the cylinder sleeve, but this method requires precise adjustment of the mutual position of several ports and the size of each port. It cannot be formed and requires a lot of effort to correct.
It was reducing productivity.

Also, since the cylinder sleeve is cylindrical,
It has also been difficult to punch out port holes with a press machine. In other words, the cylinder sleeve is thin and the high phosphorus cast iron it is made from has low toughness, so even if you try to punch out the port hole, it is likely that the material will be damaged, not to mention punching out the port hole. was.

Furthermore, in order to improve these drawbacks, it is also known to use a steel plate as a material, punch out port holes in it using a press machine, and then wind it into a cylindrical shape (for example, Utility Model Publication No. 54-29365). However, when port holes are punched in a flat plate, its bending rigidity becomes uneven, so when it is wound into a cylindrical shape, it becomes a polygon, making it difficult to accurately form it into a cylindrical shape. In addition, it was difficult to ensure perfect joints, and gas leaks easily occurred from the joints.

[Means for solving problems]

The present invention aims to solve the above-mentioned problems, and includes a boss formed with a diameter slightly smaller than the inner diameter of the cylinder sleeve, and a boss provided on the boss so as to be able to protrude and retract in radial directions in different directions. At least two punches having a shape substantially the same as the port hole of the cylinder sleeve, and a punch provided on the outside opposite to these punches, and a portion of the outer surface of the cylinder sleeve to be punched and the outer periphery of the cylinder, which is provided on the outside and facing the punches, and a cylinder extending approximately all the way around the punched portion of the outer surface of the cylinder sleeve and its outer periphery. The sleeve is equipped with at least two reverse pushing units that press and compress the sleeve toward its axis.

〔Example〕

The present invention will be explained with reference to illustrated embodiments.
In the figure, reference numeral 1 denotes an engine cylinder port machining device according to the present invention, in which a boss 3 with a diameter slightly smaller than the inner diameter of a cylinder sleeve W, which is a workpiece, is erected at the center of the upper surface of a bed 2. A punch 4, which will be described later, is provided in a retractable manner, and four pairs of reverse push units 5 are arranged outwardly from the punch 4, extending from all sides toward the punch 4. (omitted from illustration).

First, the structure of the punch 4 will be explained with reference to FIGS. 3 and 4. The boss 3 that supports the punch 4 has a cylindrical shape and is attached to the center of the upper surface of the bed 2 by four bolts at the collar 3a provided at the lower end. It is fixed. 3b is a washer provided on the collar 3a and supporting the cylinder sleeve W with the cylinder head side facing downward. A cam member 6 is fitted into the center hole 3c of the boss 3 so as to be able to move up and down, and several holes provided on the outer surface have holes approximately the same size as the port holes w at positions relative to the port holes w of the cylinder sleeve W. , a punch 4 having the same cross-sectional shape is movably supported. In addition, in FIG. 3, the port holes w are shown as an exhaust port w1 located at a relatively low position and an intake port w2 located at a high position, and in FIG. 4, a pair of left and right scavenging ports are provided symmetrically. Port w3 is shown. The cam member 6 is provided with a downward slope 6a at a position corresponding to the punch 4.
When the punch moves downward, the punch 4 moves outward. That is, the five punches 4 are provided on the boss 3 so as to be protrusive and retractable in four different radial directions. The cam members 6 are provided corresponding to the positions of the port holes w, but their phases are sequentially biased upward in the circumferential direction as one of the standards, and the cam members 6 move downward. When doing so, several punches placed outside them 4
are adapted to protrude sequentially along the circumferential direction. The reverse push unit 5 includes a die 7 and an inverted mold 8 having substantially the same curved surface as the outer surface of the cylinder sleeve W, and a slider 9 that supports them so as to press and compress the outer surface of the cylinder sleeve W toward the axis of the cylinder sleeve. The slider 9 is configured to move back and forth on a rail 10 fixed to the upper surface of the bed 2 by the action of a slider piston cylinder mechanism 11 on the back side. That is,
The inverted die 8 and the die 7 press and compress the punched portion of the cylinder sleeve W and the surrounding portion toward the axis of the cylinder sleeve. The die 7 is fixed to the outer surface of the slider 9, and the inverted mold 8 is fixed to the slider 9.
The piston-cylinder mechanism 12 for reverse pushing is connected to the piston of the piston-cylinder mechanism 12 provided in the. In this cross section, the cylinder sleeve W is provided with two upper and lower port holes w, so two pairs of the die 7, the reverse die 8, and the reverse pressing piston cylinder mechanism 12 are provided.

Next, a method of processing the cylinder sleeve W will be explained. First, the piston cylinder mechanism 11 for the slider
and the reverse-pushing piston-cylinder mechanism 12 are moved backward, and the cam member 6 is returned to the upper end. Next, a material made of a cast tube obtained by centrifugal casting and having its inner and outer diameters and end faces machined is prepared, fitted onto the outer periphery of the boss 3, and supported by a washer 3b.
Thereafter, the four pairs of slider piston-cylinder mechanisms 11 and reverse-pressing piston-cylinder mechanisms 12 are moved forward to pressurize the cylinder sleeve W toward the axis along the radial direction, thereby applying hoop stress inside the cylinder sleeve W. generate. This hoop stress is
The hoop stress generated in this embodiment is the stress generated in the circumferential direction when pressure parallel to the radial direction is applied to the ring, and is the compressive stress in the circumferential direction. In this state, when the cam member 6 is pulled down by a hydraulic piston cylinder (not shown), the punch 4 directed toward one of the punches 4 that can be protruded and retracted in different directions protrudes, pushing the inverted mold 8 back. Punch out a port hole w. At this time, the cylinder sleeve W is punched out with its periphery closed by the outer periphery of the boss 3, the die 7, and the inverted mold 8. During punching, tensile stress is generated around the hole punched by the punch 4, but this tensile stress is offset and significantly reduced by the hoop stress described above.

According to the experiments repeatedly conducted by the inventor in creating the present invention, the pressing force necessary to generate the hoop stress is influenced by the shearing force necessary to open the port hole w.
Reverse push piston cylinder mechanism 12 that pushes the die 7
It was found that the pressure at 196 kN or more is sufficient. In addition, the cylinder sleeve W is made of alloy cast iron material for cylinder liners, and its dimensions are as follows:
70mm, inner diameter 64mm. Further, the maximum shear stress applied to the material during punching was approximately 300 MPa as a result of measuring the punching load by attaching a resistance wire strain gauge to the punch 4.

At this time, the punched waste material is left in the die 7, but when the punching is completed, the slider piston cylinder mechanism 11 is operated to move the reverse push unit 5 backward, and the reverse die 8 is moved back to the original position. When the waste material is advanced to this point, the waste material is discharged to the outside.

When the cam member 6 is further lowered, the adjacent punches 4 protrude and the corresponding port holes w are punched out in the same manner, and thereafter, the port holes w arranged all around the circumference are punched out one after another. When all the port holes w have been machined, the cam member 6 is returned to the upper end, and the reverse push unit 5, which has been moved back, is moved forward again, and the punch 4, which is still protruding, is moved into the boss 3. Push it in to finish the work. Note that the method for pushing the punch 4 is not limited to this example, and any method can be used.

〔Effect of the invention〕

As described above, the present invention includes a boss to which a cylinder sleeve formed to have a diameter slightly smaller than the inner diameter of the cylinder sleeve is removably fitted;
at least two punches having substantially the same shape as the port hole of the cylinder sleeve, and provided on the outside facing these punches, and extending substantially all around the punched portion of the outer surface of the cylinder sleeve and its outer periphery. Since it is equipped with at least two reverse push units that press and compress the cylinder sleeve toward its axis, it is possible to punch the cylinder sleeve while generating compressive stress (hoop stress) in the circumferential direction. Become. Therefore,
Since the tensile stress generated around the processed portion during punching can be offset and reduced by the hoop stress, a port hole can be reliably formed by punching even in a cast iron cylinder sleeve that is brittle and prone to breakage. Compared to punching from the outside to the inside, it is easier to install a reverse press die, which tends to be relatively large.
Additionally, although small cracks and burrs may appear on the punched outer corners, they are so small that they can be ignored in terms of performance, and they are easier to correct by machining than when they occur on the inner surface. There are effects such as

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is a plan view showing the main parts of the engine cylinder sleeve port processing device according to the present invention, and FIG.
3 is an enlarged cross-sectional view, and FIG. 4 is a cross-sectional view thereof. 1...Engine cylinder sleeve port processing device, 4...Punch, 5...Reverse push unit, 6
...Cam member.

Claims (1)

[Claims] 1. A boss 3 formed to have a diameter slightly smaller than the inner diameter of the cylinder sleeve W and into which the cylinder sleeve W is removably fitted; and a boss 3 which is provided in the boss 3 in a radial direction so as to be able to protrude and retract in different directions. At least two punches 4 having substantially the same shape as the port hole w of the cylinder sleeve W are provided on the outside facing the punches 4, and are provided on the punched portion of the outer surface of the cylinder sleeve W and the outer circumference of the cylinder sleeve W over substantially the entire circumference thereof. A port processing device for an engine cylinder sleeve, comprising at least two reverse push units 5 that press and compress the cylinder sleeve W toward the axis thereof.