JPH01215437A - Method for casting casting frame for motor bicycle - Google Patents

Abstract

PURPOSE:To obtain light alloy-made casting having sufficient structural rigidity and strength and light integrated structure by dividing a die into plural blocks. CONSTITUTION:The die for base body constructural part in frame composing of stearing shaft part 1 and the main frame part 2 is made to slit dies dividing as openable/shuttable to right and left direction from straddler position of wheel body at the plane containing center line of the stearing shaft part 1. The die for the base body constructural part in the frame at rear part of the stearing shaft 1 turns the straddler side upward and divides with the upper face or lower face into upper die and lower die 6. The slit dies divided into plural pieces are formed toward the direction shifting from the stearing shaft part 1 to rear frame part 4. Then, at least one side of dies either the upper die or the lower die 6 is made to the liftable die and joinable die with another die.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention provides a main part of a motorcycle frame made of a wheel base metal, particularly an aluminum alloy, which has a lightweight body and sufficient rigidity and strength. The present invention relates to a method for casting a cast frame for a motorcycle that is cast in one piece.

(Prior art) There are various types of body frames for motorcycles, including double cradle type frames, semi-double cradle type frames, and diamond type frames.

They are classified into backbone type frames, step-through type frames, etc.

Many of these are assembled from steel pipes or plates.1
It is heavy.

However, in order to make motorcycles easier to handle, attempts have been made to reduce the weight of the vehicle body, and some have attempted to make the main frame of a light alloy.

However, because the joint of the steering shaft tube to the main frame is subject to large forces such as shocks from the front fork when the vehicle is running, the conventional structure made of steel pipes or steel plates has been simply converted to a light metal part. However, due to the material used, it is not possible to obtain sufficient rigidity and strength.

Therefore, Japanese Patent Application Laid-Open No. 81-38072 discloses a light alloy plate in which the shape is devised to give it rigidity and strength.

This main frame is shaped like a flat pipe with a longitudinally elongated cross section extending from the rear side of the main frame toward the steering shaft tube.

In addition, the double cradle type body frame is cast from aluminum alloy and divided into two symmetrical parts.The steering shaft is bolted, and the parts where there is space on both sides of the frame are bolted with connecting pipes in between. An assembled version is known from Japanese Patent Laid-Open No. 1111-8084.

(Problem to be solved by the invention) As described above, a motorcycle using a motorcycle frame made of light alloy lumber is lighter than a steel motorcycle, and its ease of handling is greatly improved. There are many advantages, and the structural strength is also taken into consideration, so there is no problem in terms of safety.

However, the frame to which light alloy lumber is joined has a problem in that it requires a large number of machining steps.

Furthermore, the frame made of light alloy casting as described in Japanese Patent Application Laid-open No. Sho ST-EAST also has the trouble of having to be assembled by sandwiching the connecting pipe with bolts or studs.

However, a one-piece light alloy cast frame for motorcycles, which has excellent rigidity and strength, has not yet appeared due to difficulties in casting technology, but if it could be cast as one piece, it would require only one assembly man-hour. Therefore, there is a long-awaited development of a casting method that can integrally cast such frames for motorcycles.

However, there is a problem in that it is not possible to cast a satisfactory frame simply by using a mold for casting an integral frame.

(Means for Solving the Problems) A method for casting a cast frame for a motorcycle according to the present invention includes:
A frame for a motorcycle was invented in response to the above-mentioned needs, and the first is a frame for a motorcycle as shown in a side view in Fig. 1, a plan view in Fig. 2, and a rear view in Fig. 3. In order to cast the steering shaft part, the main frame part (M), and the rear frame part (R) behind the main frame part, or the steering shaft part (S), as shown in FIGS. 4 and 5, , when casting a motorcycle casting frame in which the main structural members are a main frame part, a rear frame part behind the main frame part, and a down frame part (D) as an integral casting.

The steering shaft of the motorcycle casting frame (1
) and the main frame part (2).
The mold is divided into parts that can be opened and closed to the left and right when viewed from the straddle position of the vehicle body on the surface including On the other hand, separate the upper mold (5) and lower mold (8) on the upper or lower surface of the frame.
), and the mold is divided into a plurality of parts according to the direction from the steering shaft part (1) to the rear frame part (4), and at least one of the upper mold (5) and the lower mold (6) can be raised and lowered. A mold that can be joined to another mold is used as a mold, and each of the divided molds for the base structure part of the frame described above is assembled into a mold.

Light alloy molten metal is poured into the mold cavity, and after the molten metal has solidified, the mold is released.Furthermore, the motorcycle frame casting is removed from the mold in which the motorcycle frame casting remains, and the motorcycle frame is cast in one piece. The present invention is characterized by obtaining a casting for a frame for a motorcycle.

In the first invention, among each mold, a mold having a convex part (7) or a concave part (7') in the direction of mold removal has a part of the convex part (7) or a concave part (7') of the mold. , A method for casting a motorcycle casting frame with a loose-piece mold that separates from the mold when it is removed, or a collapsible core that collapses when it is removed, and a method for casting a mold for the H part of the casting or the part where the core is placed. This is a casting method for a motorcycle casting frame that is provided with at least a gas suction hole (8) for discharging gas to the outside, and a feeder (8) in the thick part of the casting or in the vicinity of the thick part. Alternatively, it is more preferable to use a casting method for a motorcycle casting frame provided with a sprue (lO).

A motorcycle frame produced by the method of casting a motorcycle casting frame of the present invention has a main frame section that branches left and right from a steering shaft section, and a rear frame section that is connected to the main frame section, or the steering shaft section that has a rear frame section connected to the main frame section. A piece with a down frame part extending downward at the rear of the part is cast.

In addition, the thick parts near the steering shaft part and the rear frame part, including at least the vicinity of the ends of the rear frame part, such as the vicinity of the steering shaft part, the end part of the rear frame part, and the vicinity of the boundary between the main frame part and the rear frame part, etc. A feeder (8) is provided in the base mold near the thick part, and in order to improve the replenishment of molten metal to the feeder (9), the sprue part (11) and the feeder (
θ) through Wk road (12). At the outer periphery of the feeder (8) where you want to maintain the molten metal temperature for a longer period of time,
In particular, one heat-generating core (!3) is used to improve the feeder effect.

Then, the mold for the base structure part of the frame behind the steering shaft part (1) is divided into an upper mold (5) and a lower mold (6) by dividing the mold on the upper or lower surface of the frame with the straddle side of the frame facing upward. At the same time, the mold is divided into a plurality of parts according to the direction from the steering shaft part (1) to the rear frame part (0), and at least one of the upper mold (5) and the lower mold (6) is a mold that can be raised and lowered, and the other In order to join with the mold and assemble with each divided mold of the base structure part of the frame,
Horizontal type (right) (19) Horizontal type (left) inside the horizontal mounting frame (18) on the lower mold base (17) on the stand @ (1B) with the push-up cylinder (14) and the auxiliary guide (15) (
20) is assembled into a mold, and the divided upper mold (5) is attached to the upper mold mounting frame (
21).

In addition, the core for configuring the main frame part (2) includes:
A skirting board (22) is attached.

When completing a vehicle body using a cast motorcycle frame, it can be used as is, and it can also be used to hold the lower part of the engine when making the vehicle body into a diamond-shaped frame, double cradle-type frame, or semi-double cradle-type frame. It is assembled by joining parts that are separately cast or processed into light alloy shaped plates to the main frame part or down frame part.

The above connection is performed by mechanical assembly using ordinary bolts or by welding.

(Function) In the casting method of a motorcycle casting frame of the present invention, a long frame is formed by integrating a main frame portion extending in one direction from the steering shaft portion and a rear frame portion or down frame portion continuous to the main frame portion. In order to cast aluminum alloy castings, the mold is divided along the main parting line on the outer periphery of the casting, so unlike a normal mold, thermal distortion may occur in some parts of the mold due to differences in shape such as the area or position in contact with the molten metal. In contrast, the casting method of the present invention does not cause warping due to the formation of parts that change and parts that do not change in the mold itself.

That is, by dividing the mold into a plurality of blocks, changes such as elongation and expansion correspond to each block depending on the amount of strain. As a result, unlike integrated molds, warping does not occur, and therefore there are no gaps between the mold mating surfaces. There is no possibility that the mold will be deformed by the heat of pouring, causing a part of the mold to break and leaking.

In particular, if a plurality of molds are divided into M-type molds, which are divided into a vertical surface portion of the frame portion and a horizontal surface portion of the frame portion with the coordinates with the straddle facing upward, and fixed in the mold flask, the mold will be molded into a mold for motorcycles. The surface of the frame does not impair its aesthetic appearance.

In addition, connecting the sprues with a runner improves hot water washing and reduces problems with thin and long hot water running.

In addition, the shape of the motorcycle frame to be cast has a structure that allows additional structures that would otherwise be required to be added to the finished vehicle body to be added with as little man-hours as possible.
It has become possible to achieve harmony with the castable shapes mentioned above, and it has become possible to cast long light alloy castings.

(Effects of the Invention) According to the casting method for a motorcycle casting frame of the present invention,
The casting frame for motorcycles has the advantage that the main parts of the frame can be cast as light alloy castings with a one-piece structure that has sufficient structural rigidity and strength and is lightweight.

The use of this cast frame for a motorcycle has the advantage of reducing the number of assembly steps when assembling the vehicle body.

In addition, the main part of the motorcycle frame can be integrally cast from light alloy, and other light alloy structures can be easily attached to the main part of the frame, resulting in a lighter body and easier handling. Another advantage is that it is easy to do.

In addition, the method for casting frames for motorcycles of the present invention has an excellent shape for the casting mold, and among the various types of motorcycle body frames, the split mold of the part corresponding to the shape is replaced. It also has the advantage of being able to

As explained in detail above, the method for casting a motorcycle frame according to the present invention is useful, and the present invention greatly contributes to the development of industry.

[Brief explanation of the drawing]

FIG. 1 is a side view of a motorcycle casting frame to be cast by the motorcycle casting frame casting method of the present invention;
Fig. 2 is a plan view thereof, Fig. 3 is a rear view, Fig. 4 is a conceptual elevational view of the mold assembly in the method of casting a cast frame for a motorcycle of the present invention, and Fig. 5 is a schematic elevational view of the mold assembly for a motorcycle of the present invention. FIG. 2 is a conceptual plan view of a mold assembly in a casting method for a casting frame. 1. Steering shaft portion; 2. Main frame portion; 3. , , , center line; 4
, , , Rear frame part, 5. ,,, upper mold;8
,,,lower mold,7. ,,,Convex part, 7'',,,,Concave part;8,,,,Gas suction hole:9.,,,,Riser;1[+
,,,, Yuguchi weir, Yuguchi 1. ,, sprue section, 12. ,,
, Runway: 13, , Exothermic core; 14. ,,,Push-up cylinder: 15,,,,Auxiliary guide; 1B,,,Base board: 17,,,,Lower die base; 18. ,,,Horizontal mounting frame; 19,,,,Horizontal (right), 20. ,,,horizontal (
Left); 21, upper mold mounting frame; 22. ,,,Baseboard;
0010. Main frame part; R, Rear frame part; D, Down frame part: S, Steering shaft part.

Claims (4)

[Claims] (1) The steering shaft, the main frame, and the rear frame behind the main frame, or the steering shaft, the main frame, the rear frame behind the main frame, and the down frame as the main structural members. When casting a motorcycle casting frame as an integral casting, the mold of the base structure part of the frame consisting of the steering shaft part and the main frame part of the motorcycle casting frame,
It is a split mold that can be opened and closed to the left and right when viewed from the straddle position of the vehicle body on a plane that includes the center line of the steering shaft. The upper mold is divided at the upper or lower surface of the frame part to form an upper mold and a lower mold, and the mold is divided into a plurality of parts according to the direction from the steering shaft part to the rear frame part, and at least one of the upper mold and the lower mold A mold that can be raised and lowered is used as a mold that can be joined to the other mold, and each of the divided molds of the base structure part of the frame described above is assembled into a mold. Molten light alloy is poured into the mold cavity, and after the molten metal has solidified. A motorcycle characterized in that the mold is released, and the motorcycle frame casting is removed from the mold in which the motorcycle frame casting remains, thereby obtaining an integrally cast motorcycle frame casting. Casting method for casting frames. (2) Among each mold, if the mold has a convex part or a concave part in the direction of mold removal, there is a loose piece mold that separates from the mold when the mold is removed or collapses when the mold is removed. The method for casting a cast frame for a motorcycle according to claim 1, wherein a collapsible core is arranged. (3) The method for casting a cast frame for a motorcycle according to claim 1, wherein the thick part of the casting or the part of the mold where the core is arranged is provided with a gas suction hole for discharging at least gas to the outside. (4) In the thick part of the casting or in the vicinity of the thick part,
The method for casting a cast frame for a motorcycle according to claim 1, wherein a riser or a sprue is provided.