JPH0242583B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is particularly directed to two types of cylinders that do not use a cylinder liner.
The present invention relates to a die casting device suitable for casting cylinders for cycle engines.

(Prior Art) For example, a partition wall 73 is formed between a cylinder surface 71 formed on the inner surface of a cylinder 70 for a normal two-stroke engine and a scavenging passage 72 as shown in FIG. A scavenging port 74 that opens to the cylinder surface 71 is formed in the partition wall 73 . When such a cylinder 70 for a two-stroke engine is viewed from the direction in which the core that forms the inner surface of the cylinder is pulled out (from the left in Fig. 6), an undercut occurs at the scavenging port 74, which is a problem when casting using a shell mold. In the case of die casting, there is no particular problem, but in the case of die casting, the core cannot be pulled out. Therefore, a conventional two-stroke engine cylinder 70A manufactured by die casting has a cylinder surface 71A and a scavenging passage 7, as shown in FIG.
2A, a slide core 78 inserted from the direction of the joint surface 79 between the fixed mold 76 and the movable mold 77 forming the outer shape of the cylinder 70A can be pulled out. ing.

(Problems to be Solved by the Invention) The two-stroke engine cylinder 70A manufactured by such a conventional technique has a cylinder surface 71
Since there is no partition wall in the lower half of A, the cylinder surface 71A
The contact area between the piston and the piston (not shown) fitted into the finished cylinder surface is reduced, and this makes it easier for the piston to move in the radial and inclination directions, especially in the direction in which the scavenging passage 72A is formed. However, there are problems in that piston slap noise is likely to occur or durability is reduced. The present invention has been developed by adding a device to the slide core that forms the inner surface of the cylinder, so that the two
The present invention aims to solve the above problem by providing a die casting device that can cast a cylinder 70 for a cycle engine.

(Means for Solving the Problems) For this purpose, the die-casting device for a cylinder for a two-stroke engine according to the present invention includes a fixed die 10 for forming half of the outer shape of the cylinder, and a fixed die 10 that is provided to be openable and closable with respect to the fixed die. A movable mold 11 for molding the remaining half of the outer shape of the cylinder, and a movable mold 11 that is movably inserted into the space between the two molds 10 and 11 that are joined to each other from the direction of the joint surface 17 of the two molds. In the two-stroke engine cylinder die-casting device comprising a slide core 20 for molding the inner surface of the cylinder, the slide core 20 is fitted into the cylindrical outer circumferential portion 21 to form the tip portion 2.
5a is composed of a core portion 25 that protrudes from the core portion 5a, and the tip portion 2 of the core portion 25 is provided at the tip of the outer peripheral portion 21.
A protrusion 22 is integrally formed along a part of the outer circumference with a slight gap 27 between it and the outer circumference of the core 5a to form a scavenging passage. A guide hole 26 formed in the diametrical direction in the middle of the portion 25a supports a slide insert core 30 that forms a scavenging port so as to be retractable, and a slide key inserted into the core portion 25 so as to be slidable in the longitudinal direction. At the tip of 35 is the slide insert core 30.
The sliding core engages with the cam follower 30a formed in the slide key, and moves the slide insert core to a protruding position where its tip surface substantially contacts the inner surface 22a of the tip portion of the protruding portion 22 and the same tip surface. This is characterized in that a cam groove 36 is provided to allow the core portion 25 to move between a retracted position which is inside the outer circumferential surface of the core portion 25.

(Function) The movable mold 11 is joined to the fixed mold 10, the slide core 20 is inserted, the slide key 35 moves in a predetermined direction, and the slide insert core 3 provided in the core portion 25 is moved.
When the molten metal is injected in a state in which the tip surface of the cylinder 0 is in contact with the inner surface 22a of the tip end of the protruding portion 22 at the tip of the outer peripheral portion 21, a partition wall is formed between the scavenging passage and the cylinder surface by the gap 27. Then, a two-stroke engine cylinder with a scavenging port formed by a sliding core is cast. Next, moveable type 1
1 is separated from the fixed mold 10 and the slide key 35 is moved in the opposite direction to the predetermined direction, the slide core 30 is separated from the scavenging port by the action of the cam groove 36 and moved inside the outer peripheral surface of the core 25. Retract to the retracted position. If the slide core 20 is moved backward in this state, the slide core 20 can be pulled out without the slide core in which the scavenging ports are formed interfering with the partition wall, and the cast two-stroke engine cylinder can be taken out. .

(Effects of the Invention) As described above, the present invention provides a two-stroke engine in which a partition wall is formed between the scavenging passage and the cylinder surface, and a scavenging port that opens to the cylinder surface is formed in the partition wall at the tip of the scavenging passage. The cylinder for use can be cast by die casting. Therefore, the piston slap noise of a two-stroke engine using a die-cast cylinder can be reduced and the durability can be improved.

(Example) First, the overall structure of the die casting apparatus of this example will be explained mainly with reference to FIGS. 3 and 4.
A fixed mold 10 consisting of a fixed mold 10a and a fixed nested mold 10b fixed thereto is fixed to a die plate 12, and a movable mold 11a and a movable nested mold 1 are fixed to the die plate 12.
The movable die 11 consisting of 1b is fixed to the movable die plate 13 via the die block 14, and the fixed die 1
It can be opened and closed with respect to 0. Both types 10,
11, each half of the outer shape of the cylinder for a two-stroke engine is formed. The inner surface of a two-stroke engine cylinder is located on the tip side (right side in the drawing) of the slide holder 40, which is guided and supported by the movable mold 11 via a guide groove 19 formed parallel to the joining surface 17 of both molds 10 and 11. Slide core 2 to mold
0 is fixed, and can be inserted into the space formed between the molds 10 and 11 from the direction of the joint surface 17. This slide core 20 is driven forward and backward by a cylinder device 45 attached to the movable mold 11 via a gate-shaped bracket 44. The fixed nesting mold 10b has an intake passage (numeral 76 in Fig. 6).
A slide core 51 is fixed to the tip of a slide member 50 that is guided and supported by the movable mold 11 in a direction parallel to the joint surface via a guide groove 19a. The slide member 50 and the slide core 51 are of both types 10 and 1.
1 is retracted by the spring 53 in the open state, but when the molds 10 and 11 are joined as shown in the figure, the inclined pin 52 fixed to the fixed mold 10 is inserted into the guide hole 50a as shown in FIG. When engaged, the slide member 50 and the slide core 51 move forward, and the tip 51a of the slide core 51 forming an exhaust passage (see reference numeral 75 in FIG. 6) comes into contact with the slide core 20 by the slide stopper 18a. It is becoming more and more common.

As shown in the figure, when both molds 10 and 11 are closed, the stepped portion 20a of the slide core 20 is in contact with the movable nested mold 11b, and the tip portion 51a of the slide core 51 is in contact with the slide core 20, this condition occurs. A cavity A having the same shape as the product is formed between the two. Molten aluminum from an injection device (not shown) provided at the lower part of the fixed mold 10 is pressurized and filled into the cavity A through a splitter 65, a runner 66, and a sprue 67 formed in the movable mold 11. It's summery. Further, the movable mold 11 is provided with an extrusion pin 16 for extruding the cast product and attached parts such as runners, and an extrusion plate 15 for operating the extrusion pin 16.

Next, referring mainly to FIGS. 1 and 2, the slide core 20 and slide core 30, which constitute the main parts of the present invention, will be explained. The slide core 20 has a cylindrical outer peripheral part 21 and a distal end part 2 that is fitted inside the cylindrical outer peripheral part 21.
5a consists of a core portion 25 that protrudes beyond the outer peripheral portion 21, and both members 21 and 25 are integrally fixed to the distal end side of the slide holder 40. A scavenging passage is formed at the tip of the outer circumferential portion 21, with a slight gap 27 between it and the outer circumferential surface of the tip portion 25a of the core portion 25, extending halfway along a part of the outer circumferential surface in the circumferential direction. (See reference numeral 72 in FIG. 6) A pair of protrusions 22, 22 are integrally formed.
Further, at the tip of the outer circumferential portion 21, as shown mainly in FIGS. 2 and 4, a tip portion 25a of the core portion 25 is located at an intermediate portion in the circumferential direction of both the protruding portions 22, 22.
A protrusion 23 is integrally formed along the outer circumferential surface of the air conditioner 23 so as to extend partway along the outer circumferential surface of the air conditioner 23 without a gap to form an auxiliary scavenging passage.

A rectangular guide hole 26 is formed in the diametrical direction of the tip 25a of the core 25 at a position corresponding to the tip of the protrusion 22, and a pair of sliding cores 30, 30 are inserted into the guide hole 26. It is guided and supported so that it can appear. Each slide core 30 is mainly formed by integrally connecting the closed side of a U-shaped main body with a round bar-shaped cam follower 30a, as shown in FIG. Further, a guide hole 28 having a rectangular cross section is formed in the core portion 25 along its longitudinal direction to a position beyond the guide hole 26, and a strip-shaped slide key 35 can be slid in the longitudinal direction in this guide hole 28. A cam follower 30a of the slide core 30 is engaged with a Y-shaped cam groove 36 formed at the tip of the slide key 35.

On the other hand, the slide holder 40 is provided with a slide rod 41, and this slide rod 41 has an integrally formed flange portion 41a that connects the rear end surface 25b of the core portion 25 and the stepped portion 40a of the slide holder 40.
It is possible to move relative to the slide core 20 and the slide holder 40 in the axial direction only in the range where the slide core 20 and the slide holder 40 come into contact with each other, and relative rotation is prevented by the pin 43. Thus, the rear end of the slide key 35 is connected to the slide rod 41 via the pin 42.
The flange portion 41a of the slide rod 41 is the core portion 2.
At the forward end that comes into contact with the rear end surface 25b of 5,
As shown in FIG. 1, the cam follower 30a engages with the distal end side of the forked part of the cam groove 36, and each slide insert core 30 has its distal end surface on the side of the core section 22 at the distal end of the protruding section 22 of the outer peripheral section 21. At the protruding position where it abuts the surface, that is, the inner surface 22a, and at the retracted end where the flange portion 41a abuts the stepped portion 40a, the cam follower 30a is at the proximal end side where the cam grooves 36 meet, as shown in FIG. When engaged, each sliding core 30 assumes a retracted position where its tip end surface is recessed from the outer peripheral surface of the core portion 25. In addition, in the protruding position, a slight gap may be provided between the tip surface of the slide insert core 30 and the tip inner surface 22a of the protruding portion 22 to the extent that the molten metal does not enter.

The slide rod 41 is coupled to the piston rod 46 of the cylinder device 45 via a coupling ring 47, and when the piston rod 46 moves forward, the flange portion 41a comes into contact with the rear end surface 25b of the core portion 25, and the slide insert core 30 is brought to the protruding position. After that, move the slide core 20 forward and move the piston rod 46
When the flange portion 41a moves backward, the flange portion 41a
The slide core 20 is moved back after the slide core 30 is placed in the retreat position by abutting on the slide core 20.

Mainly as shown in FIG. 4, the slide holder 4
A cooling water supply passage 60 and a discharge passage 61 are provided in the outer peripheral part 21 of the slide core 20 and the slide core 20, and these passages 60 and 61 communicate with each other through an annular passage 62 formed between the outer peripheral part 21 and the core part 25. has been done.
Three cooling water channels 64 provided along the longitudinal direction within the core portion 25 are communicated with the annular channel 62 through a communication channel 63 .

Next, the overall operation of this embodiment will be explained.

When the cylinder device 45 is actuated to advance the piston rod 46 in a state where the movable mold 11 is separated from the fixed mold 10, the flange portion 41 first moves forward.
The slide key 35 moves forward until the tip a comes into contact with the rear end surface 25b of the core 25, and the slide insert core 30 moves forward to the protruding position.Subsequently, the slide holder 40 and the slide core 20 move forward, and the stepped portion 20
a comes into contact with the movable nesting die 11 and stops. In this state, if the movable mold 11 is joined to the fixed mold 10 and the molds are clamped, the slide core 20
When inserted into the space formed between 0 and 11, the slide core 51 is prevented from retreating by the slide stopper 18 provided on the fixed mold 11, and the slide core 51 advances until the tip 51a hits the slide core 20. The slide stopper 18a prevents the slide stopper 18a from moving backward.
The tip end surface of each sliding core 30 is in contact with the tip inner surface 22a of the protrusion 22. Next, when the cavity A formed between these members is pressurized and filled with molten aluminum from an injection device, a partition wall 73 between the scavenging passage 72 and the cylinder surface 71 is formed by the gap 27, and the slide enters. A cylinder 70 for a two-stroke engine in which a scavenging port 74 is formed in a partition 73 at the tip of a scavenging passage 72 is cast using the core 30 .

Next, when the movable mold 11 is separated from the fixed mold 10, the slide core 51 is moved backward by the action of the inclined pin 52. Next, when the cylinder device 45 is actuated to move the piston rod 46 backward, the flange portion 41a of the slide rod 41 first touches the slide holder 4.
Slide key 35 until it comes into contact with step 40a of
is retracted, and the sliding core 30 is removed from the scavenging port 74 by the action of the cam groove 36, and is retracted to a retracted position where its tip end surface is inside the outer circumferential surface of the core portion 25. As a result, the partition wall 73 between the scavenging passage 72 and the cylinder surface 71 and the sliding core 30
Since there is no interference with the slide holder 40, if the piston rod 46 is moved further back, the slide holder 40 will move back.
The slide core 20 is pulled out from the inner surface of the cylinder. Next, the extrusion plate 15 is operated to cast the 2
The cycle engine cylinder 70 is pushed out from the movable mold 11 by the pushing pin 16 and taken out. Next, a mold release agent is applied to the surfaces of each mold 10, 11, slide core 20, etc. using compressed air, and the surfaces of the slide core 20 and the like are cleaned, resulting in the initial state described in the explanation of this operation, and one cycle of processing is completed. Thereafter, a cylinder for a two-stroke engine is cast in the same manner.

Cast cylinder 70 for two-stroke engine
This is completed by machining the cylinder surface 71 and other parts, and applying hard chrome plating to the machined cylinder surface. The cylinder for a two-stroke engine to which the present invention is applied is not limited to one in which the cylinder head is integrally molded as in this embodiment, but may be one in which the cylinder head is formed separately.

[Brief explanation of the drawing]

1 to 5 show an embodiment of a die-casting device for a two-stroke engine cylinder according to the present invention, in which FIG. 1 is a horizontal sectional view of the main part, FIG. Figure 3 is a horizontal sectional view of the whole with some parts omitted, Figure 4 is a cross-sectional view of Figure 3, and Figure 5 is a cross-sectional view of Figure 3.
The figure is a partial sectional view showing a state in which the sliding core is retracted, Figure 6 is a sectional view showing an example of a cylinder for a normal two-stroke engine, and Figure 7 is a two-stroke engine cast using a conventional die-casting machine. It is a sectional view showing an example of the cylinder for use. Explanation of symbols 10...Fixed type, 11...Movable type, 1
7... Joint surface, 20... Slide core, 21... Outer periphery, 22... Projection, 22a... Inner surface, 25... Core,
25a... Tip portion, 26... Guide hole, 27... Gap,
30...Slide core, 30a...Cam follower,
35...Slide key, 36...Cam groove.

Claims (1)

[Claims] 1. A fixed mold for forming half of the outer shape of the cylinder,
A movable mold that is openable and closable with respect to the fixed mold and molds the remaining half of the outer shape of the cylinder, and a movable mold that is movable from the direction of the joint surface of the two molds into the space between the two molds that are joined to each other. In a two-stroke engine cylinder die-casting machine, the slide core is fitted into a cylindrical outer circumferential portion and the tip thereof is inserted into the cylinder to form the inner surface of the cylinder. A scavenging passage is provided at the tip of the outer circumferential portion and extends halfway along a part of the outer circumferential surface with a slight gap between the tip of the outer circumferential portion and the outer circumferential surface of the tip of the core. A protruding portion for forming a scavenging port is integrally formed, and a guide hole formed in the diametrical direction midway in the tip of the core portion supports a sliding core for forming a scavenging port in a retractable manner. The tip of the slide key, which is slidably inserted in the longitudinal direction, engages with a cam follower formed on the slide insert core, and as the slide key advances and retreats, the tip surface of the slide key engages with the cam follower formed on the slide insert core. 2, characterized in that a cam groove is provided for movement between a protruding position where the protruding part substantially contacts the inner surface of the distal end thereof and a retracted position where the distal end surface thereof is inside the outer circumferential surface of the core part. Die-casting equipment for cycle engine cylinders.