JP2001150029A - Device for reforming shaft bend - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for reforming shaft bend that works with the high efficiency resulting from less frequent reforming and not causing any local bends, and that also leaves no flaws on the work shaft surface. SOLUTION: The acute-angled parts of the pillow blocks 2 are removed and the pressing part 4b of the reform ram 4 is shaped into a curved surface, the radium R of which and the span L between the pillow blocks 2 are arranged to be R/L=3.0 to 4.5. That is, the value of the radius R is smaller than or equal to the curvature radius ρ to be obtained according to the general formula dealing with the inclination and flexure by bend moment in the elastic region of the shaft. Therefore, as no stress concentration occurs which may lead to local bends, the shaft straightening power can be improved and the number of reforming can be reduced as well, leaving no flaws on the shaft surface at the time of reforming.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a straightening device for straightening a shaft, and more particularly, to a straightening device capable of straightening a shaft with a small number of straightening operations and having no scratch on the shaft surface. It is.

[0002]

2. Description of the Related Art A workpiece is supported and rotated, the amount of deflection (bending amount) from the center line of the workpiece is measured, and the maximum deflection portion is pressed with a correction ram to correct the bending of the shaft. The apparatus is disclosed in JP-A-48-81766.
It is publicly known from Japanese Patent Publication No. According to the above publication, the work is supported and rotated, the amount of deflection (bending amount) from the center line of the workpiece during rotation is measured, the maximum amount of deflection and its position are stored, and at the same time, the amount of deflection of the workpiece and the like are stored. In order to determine the pushing amount of the straightening ram according to the properties of the work, and to stop and fix the rotation of the work at a fixed position, the pushing of the straightening ram is performed based on a pre-assembled program and the maximum swing amount of the work and the stored value of the position. The amount is calculated and determined, the work is further rotated to fix the bending direction at a fixed position, and the operation of correcting the bending of the work by lowering the correction ram by the predetermined amount is automatically performed.

[0003]

However, recently,
When straightening a material having a low Young's modulus, such as a titanium alloy engine valve that has come to be used to reduce the weight of the engine drive part, when the above-described straightening operation is performed by lowering the straightening ram, As shown in FIG.
When the radius r of the circular curved surface of the pressing portion 14a of the straightening ram 14 is small and the contact area is small, at the stage where the pressing process for straightening is completed, as shown in FIG. No correction can be made due to local bending caused by concentration of stress, and as shown in FIG. 3, sharp portions 15b and 12a are formed on the pressing portion 15a of the correction ram 15 or the support base 12 of the work 3 as shown in FIG. If you have
There was a weak point that the surface of the shaft portion 3a of the work 3 was damaged. 2 and 3 for easy explanation.
In both cases, the bending of the shaft portion 3a is exaggerated. Therefore, an object of the present invention is to provide a straightening device that does not cause local bending and can perform an efficient straightening operation with a smaller number of straightening times and that does not damage the surface of a shaft portion of a work. .

[0004]

According to a first aspect of the present invention, a work is rotated on a support table, and the amount of deflection from the center line of the work, that is, the amount of bending is measured. In a bending correction device for a shaft for correcting the bending of a work by pressing the maximum amount portion with a correction ram, the pressing portion of the correction ram is formed into a circular curved surface curved in the direction of the work axis, It is characterized in that an acute angle portion of the support is removed. The invention of claim 2 is
A relationship between a radius R of the circular curved surface of the pressing portion of the correction ram and a span L of the support table is R / L = 3.0 to 4.5.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a three-dimensional view of a straightening ram of a straightening device according to an embodiment of the present invention.
(B), (c) is an explanatory view of a straightening device according to an embodiment of the present invention, FIG. 1 (b) is an explanatory view before pushing a straightening ram, and FIG. 1 (c) is an explanatory view after pushing. is there. Note that, for the sake of simplicity, the bending of the shaft in FIG. 1 is exaggerated. In FIG. 1B, the support span L is about 7
An engine valve (work) 3 made of a titanium alloy is placed on a pair of supports 2 set to 0 mm, and a shaft portion 3a
Is rotated by a rotating device (not shown), so that the vertex of the bent portion is set upward with the portion where the maximum amount of bending is measured by the detector (not shown) being substantially at the center. The corners of the support base 2 are provided with an R surface 2a except for the acute corners. A correction ram 4 is set on the upper portion of the work 3 at the center of the support 2 and is connected to a lowering drive device (not shown). The correction ram 4 is formed in a thick plate shape, and the surface 4a of the thick plate is parallel to the axial direction of the work 3 (the thickness direction is perpendicular to the axial center).
The pressing portion 4b is set on a circular curved surface having a radius R of about 300 mm. The reason for this will be described later.
In FIG. 1 (c), the correction ram 4 is pushed to a predetermined pushing amount ε, that is, a stress point (a point where correction is possible) in a plastic deformation region slightly beyond the elastic deformation region of the shaft. The portion 3a is pressure-corrected.

Next, the operation of the present embodiment will be described. In FIG. 1B, a work 3 placed on a support table 2 is rotated by a rotating device (not shown), a maximum bending amount of the shaft portion 3a is measured by a detector (not shown), and stored in a storage device (not shown). You. At this time, the work 3 is set by the rotating device so that the apex of the maximum bend is on the top. An appropriate pushing amount ε (see FIG. 1C) is calculated from a stored maximum bending amount and other properties by an arithmetic unit (not shown), and a lowering drive unit (not shown) is driven to move the correction ram 4 to the position shown in FIG. As shown in FIG. At this time, the pressing portion 4b of the correction ram 4 has a radius R (300 m in this embodiment) calculated by a method described later.
m), and the indentation ε is determined up to the stress point (correctable point) in the plastic deformation region slightly beyond the elastic deformation region of the shaft, so that the shaft portion 3a
There is no concentration of stress on the shaft portion 3a, and no local bending occurs in the shaft portion 3a after straightening, and the straightness after straightening is improved.

Here, a method of calculating the radius R of the circular curved surface of the pressing portion 4b of the correction ram 4 will be described. The radius R is a general formula for the inclination and deflection of the beam due to the bending moment.

Ρ = −EI / M

From this, the radius of curvature ρ of the deflection curve of the beam is obtained, and this value ρ is approximated to the radius R of the circular curved surface of the correction ram 4 (this embodiment is equal to or less than). Here, I is the second moment of area, M is the bending moment, and E is the longitudinal elastic modulus. If the radius R of the pressing portion 4b of the correction ram 4 is smaller than the radius of curvature ρ, the corner 3b does not come into contact with the surface of the shaft portion 3a when pushed, so that the shaft portion 3a is not damaged. Further, even if the dimension of the radius R is considerably smaller than ρ, the effect continues, and R /
Even if the value of L is 3.0, a sufficient effect is recognized. That is,
The radius of curvature ρ of the deflection curve of the valve shaft is substantially constant, and the value of R / L at which local bending does not occur is in a range of 3.0 or more. If the value of R / L is less than 3.0, a local bending state as shown in FIG. 2B may occur. Also,
If the value of R / L exceeds 4.5, the shaft surface may be damaged depending on the value of the pushing amount ε.

[0010]

The present invention has the following effects because it is configured as described above. That is, an acute angle portion of the support is removed, the shape of the pressing portion of the correction ram is formed into a circular surface, and the relationship between the radius R of the circular surface and the span L of the support is represented by R / L =
3.0 to 4.5, that is, the value of the radius R is approximated (or less than or equal to) to the radius of curvature according to the general formula relating to the inclination and deflection of the beam due to the bending moment in the elastic deformation region of the shaft. Since the straightness is improved without a significant bending, the number of corrections can be reduced and the correction can be performed efficiently, and the shaft surface is not damaged during the correction.

[Brief description of the drawings]

FIG. 1A is a three-dimensional view of a straightening ram of a straightening device according to an embodiment of the present invention. FIG. 1B is an explanatory diagram of a straightening device according to an embodiment of the present invention, and is a diagram before pushing.
FIG. 1C is an explanatory diagram of the straightening device according to one embodiment of the present invention, and is a diagram after the pressing.

FIG. 2 (a) is an explanatory view of a conventional straightening device, before pressing. FIG. 2 (b) is an explanatory view of a conventional straightening device, and is a view after pushing.

FIG. 3 is an explanatory view of another embodiment of the conventional straightening device, and is a view after pushing.

[Explanation of symbols]

 2 Support 2a R surface 3 Engine valve (work) 3a Shaft 4 Straightening ram 4b Pressing part

Claims (2)

[Claims] A work is rotated on a support table, a runout amount from a work center line, that is, a bending amount is measured, and a portion of the maximum runout amount is pressed by a correction ram to bend a shaft for correcting the work bending. In the straightening device, the pressing portion of the straightening ram is formed into a circular curved surface curved in the direction of the axis of the work, and the acute angle portion of the support base is removed. 2. The relationship between the radius R of the circular curved surface of the pressing portion of the correction ram and the span L of the support table is represented by R / L = 2.
2. The shaft straightening device according to claim 1, wherein the value is 3.0 to 4.5.