JP2914058B2 - Spline molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spline forming method.

[0002]

2. Description of the Related Art Machine parts having splines include, for example, various gears, and automobile parts include, for example, an input shaft which is a shaft having internal and external splines for transmitting engine output to a transmission.

[0003] As a spline forming method for forming a spline on a work which is a material to be processed into parts such as gears and shafts, conventionally, a work to be formed with a spline is formed by using a molding die provided with a spline forming blade. A method is generally used in which a spline is formed into a work by being pushed into the work by the other forming die. This method is further roughly classified into a method of forming a spline without applying a back pressure to the end face of one end of the workpiece where the spline is to be formed, and a method of applying a constant back pressure to the end face of the one end where the spline of the workpiece is to be formed. Spline forming method can be divided into

[0004]

However, each of the conventional spline forming methods has the following disadvantages.

The first method will be described in more detail with reference to the drawings. In FIG. 3, 1 is a work, 2 is a mandrel having a spline forming blade 3 provided radially, 4 is a guide hole formed in one end of the work 1, 5 is a lower mold, 6 is a mandrel 2 and a lower mold 5. Is the gap between As shown in FIG. 3A, when one end of the cylindrical shape of the work 1 is pushed into the gap 6 by an upper die (not shown) in the direction of a thick arrow, the material of the work 1 is thinned at the tip of the work 1 in the figure. Flows like That is, the material of the work 1 above the forming blade 3 is more likely to flow toward the end face 7 having less resistance than flowing into the concave groove between the forming blades 3.

FIG. 4 is an enlarged view of a portion I surrounded by a dashed line in FIG. In the figure, 8 is sink, that is, work 1
Is reduced due to the material flowing toward the end face 7 side.
When sink 8 occurs, the material of the work 1 does not turn to the small diameter side of the inner spline, and therefore, the inner spline is not appropriately formed at the entrance portion (the end of one end where the inner spline of the work 1 is to be formed).

In this method, as shown in FIG. 3B, when molding proceeds to a certain extent, the work 1 is strongly pressed by the lower mold 5 and the mandrel 2, and the space between the lower mold 5 and the work 1 and the mandrel 2 is formed. As shown by an upper arrow in the figure, a frictional force is generated between the workpiece 1 and the workpiece 1, so that the material of the workpiece 1 does not easily flow toward the end face 7, so that the groove between the forming blades 3 is also filled with the material.

Next, the method will be described in more detail with reference to the drawings. In FIG. 5, reference numeral 9 denotes a knockout sleeve, and the others have the same meaning as in FIG. The knockout sleeve 9 is brought into contact with the cylindrical end face 7 of the work 1,
When the work 1 is pushed in the direction opposite to the direction of the thick arrow by the upper die (not shown) while giving a constant back pressure of an appropriate size in the direction of the thick arrow, a gap 6 exists as in FIG. Therefore, at the tip of the work 1, the material of the work 1 flows into the groove between the forming blades 3 as shown by the thin arrow in the figure. Therefore, unlike the case where the method is used, sink 8 does not occur, and the inner spline is appropriately formed even at the tip of one end of the work 1 where the inner spline is to be formed.

However, in the method described above, since the spline is formed while applying a constant back pressure to the end face 7 by the knockout sleeve 9, the work 1 is pressed in the direction of compression by the upper mold and the knockout sleeve 9 even when the forming proceeds. Will continue to do so. As a result, an excessive compressive force is applied to the work 1, which may deform and / or break the work 1, and may lower the molding accuracy. Further, since the work 1 is firmly adhered to the lower mold 5 and the mandrel 2, when the work 1 is protruded by the knockout sleeve 9 after the end of the spline molding, the work 1 and the mold may be deformed and / or damaged.

An object of the present invention is to solve the above-mentioned problems of the prior art, and it is an object of the present invention to prevent deformation and / or breakage of a workpiece at the time of forming a spline, and to improve spline forming accuracy. , Deformation of the workpiece and the mold when the workpiece is released from the mold after the spline molding, and / or
Another object of the present invention is to provide a spline forming method that can prevent breakage and can be easily performed.

[0011]

That is, according to the spline forming method of the present invention, a work to be formed with a spline is placed in one forming die provided with a spline forming blade while applying back pressure to the work by the other forming die. in the spline forming process for forming a spline in the work is pushed, and wherein the highest Mel that the back pressure at the start of the spline molding.
In the method of the present invention, the back pressure is
It is preferable to decrease the value accordingly.

[0012]

[Function] Increase back pressure at the start of spline molding, preferably
Properly is by gradually decreasing as appropriate with the progress of the spline molding, not applied workpiece and excess pressure in the mold, the work at the time of the spline molding deformation and / or breakage,
In addition, deformation and / or breakage of the workpiece and the mold when the workpiece is released after the end of the spline molding are prevented.

[0013]

The following examples illustrate the process of the present invention in more detail.

In practicing the present invention, the following points should be noted. That is, the back pressure is selected so as to be an appropriate value with respect to the forming load, and the work is placed under one of the molds having the spline forming blade, for example, the mandrel having the spline forming blade along the outer periphery of the tip. The spline of the workpiece may be provided by bringing a suitable member, such as a knockout sleeve, into contact with the end face of one end to be molded when the other molding die, for example, the upper die is pressed into the mold.

The maximum back pressure at the start of spline forming means that the highest pressure in a predetermined pressure range to be applied to the work at the time of spline forming is applied to the opposite side of the pressing side (for example, upper die) of the work at the start of spline forming. Means

Next, the back pressure is gradually reduced as the spline forming progresses. The method of gradually reducing the back pressure may be any method as long as the back pressure is gradually reduced in a desired pattern selected in consideration of the type of the spline molded product or the like so that a spline molded product of the desired performance is obtained. . That is, for example, the back pressure may be gradually reduced from the maximum pressure at the start of the spline forming stepwise or continuously, or a combination thereof, and the back pressure may be completely eliminated during the spline forming.

The desired back pressure gradual pattern can be implemented by manual or automatic control of the back pressure during spline forming, such as computer control or a combination thereof.

The splines to be formed may be inner splines, outer splines, or a combination thereof. The work, spline mold, controller and the like used in the method of the present invention can be those commonly used in spline molding. If necessary, the obtained spline-formed part may be subjected to further finishing.

FIG. 1 is an explanatory view of an embodiment of the spline forming method of the present invention. As shown in FIG.
To push one end of the work 1 provided with the guide hole 4 into the gap 6 between the lower mold 5 and the mandrel 2 (the forming blade 3 is provided radially along the outer periphery of one end). At this time, a back pressure F (compression force) of about 1/2 to 1/4 of the forming load is first applied to the knockout sleeve 9 by a pressing pin 11 driven by a suitable means such as a hydraulic device.
And press it.

When the work 1 is further lowered after the end face 7 of the work 1 comes into contact with the forming blade 3, the forming blade 3 starts to form a spline along the inner periphery of the guide hole 4 as shown in FIG. After the start of molding, as shown in FIG. 2, the compression force is reduced by gradually releasing the back pressure as the upper die stroke increases, that is, as the upper die 10 descends. For example, FIG. 1B corresponds to a state in which the upper die stroke is 10 to 15 mm, and the back pressure in this case is 1 / 2F. Then, for example, as shown in FIG.
0mm position (the upper mold 10 is 20-30mm from the start of molding)
The back pressure is eliminated at the lowered position), and thereafter, the remaining spline is formed without the back pressure as shown in FIG.

After the spline forming is completed, the upper mold 10 is raised, and then the knockout sleeve 9 is pressed by the pressing pin 11 to push the work 1 out of the lower mold 5 to obtain the spline-formed work 1. .

[0022]

According to the spline forming method of the present invention, when forming a spline on a work as described above, the back pressure applied to the work is maximized at the start of the spline forming, which is preferable.
In other words , the work and the mold are not subjected to excessive pressure because the pressure gradually decreases as the spline forming progresses, and the work is deformed and / or damaged during the spline forming, and when the work is released after the spline forming is completed. Deformation and / or breakage of the work or the mold can be prevented. As a result, the small diameter portion of the spline in the early stage of molding, which cannot be avoided in the conventional spline molding method, is eliminated, and the spline can be molded without applying excessive pressure even in the later stage of molding, so that the accuracy can be improved over the entire length. It is possible to mold splines well,
The quality of the product obtained has improved.

In addition, since the work does not firmly adhere to a spline forming die, such as a lower die and a mandrel,
For example, when the workpiece is ejected by the knockout sleeve after the spline molding is completed, there is no risk of deforming and / or damaging the workpiece or the mold, and the ejecting operation can be easily performed since there is no need to press the workpiece very strongly. .

Further, since the method of the present invention can be carried out using a conventional spline forming apparatus as it is, there is no need to invest in new equipment and it is easy to carry out.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of a spline forming method of the present invention.

FIG. 2 is a diagram showing a relationship between an upper die stroke and a back pressure when performing spline forming using the method of the present invention.

FIG. 3 is a diagram illustrating a flow state of a work material during spline forming in an example of a conventional spline forming method.

FIG. 4 is an enlarged view of a portion I surrounded by a dashed line in FIG.

FIG. 5 is a diagram illustrating a flow state of a work material during spline forming in another example of the conventional spline forming method.

[Explanation of symbols]

 Reference Signs List 1 work 2 mandrel 3 forming blade 4 guide hole 5 lower mold 6 gap 7 end face 8 sink 9 knockout sleeve 10 upper mold 11 pressing pin

Claims (1)

(57) [Claims] 1. A spline forming method for forming a spline on a work by pressing a work to be formed with a spline into one forming die having a spline forming blade and applying a back pressure to the work with the other forming die. spline molding wherein the highest Mel that the back pressure at the start of the spline molding.