JPH0576940A - Method for forming leaf spring - Google Patents

Abstract

PURPOSE:To mass-produce spring with high precision of spring dimension and spring characteristic by stabilizing a working condition when bending is carried out. CONSTITUTION:In the method for forming a leaf spring providing with a lower die 2 having a curved surface used for bending, a clamper 3 fixing part of a material to be worked to the lower die 2 and a driven-rotatable roller 1 pressing continuously along the curved surface of the lower die 2, a notched end face of a notched roller 1b is adjusted to the end face of the clamper 3 thereby the leaf spring is formed so that the adjusted position makes a work starting position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leaf spring forming method,
For example, the present invention relates to a leaf spring forming method suitable for forming a leaf spring used as a support spring of a magnetic head by plastic working of a leaf material.

[0002]

2. Description of the Related Art Conventionally, as an example of a processing method for forming a spring portion by plastically deforming a plate material, for example, US Pat.
The one described in No. 03567 is known.

A conventional example will be described with reference to FIGS.

FIG. 2 is a view showing a main part of a processing start state according to a conventional method (a conventional leaf spring forming method using a roller). A lower die 2 having a curved surface used for bending, a clamper 3 for fixing a part of the work piece 4 to the lower die 2, and a spring forming portion of the work piece 4 are continuously formed along the curved surface of the lower die. In a method of forming a leaf spring, which is processed by using a forming apparatus having a driven rotatable roller 1 for pressing, the conventional method is to continuously press along the curved surface of the lower mold 2 using a cylindrical roller 1. Was there. When pressing the roller 1 against the workpiece 4,
The roller 1 rolls along the upper surface of the clamper 3 and the workpiece 4
Was in contact with.

FIG. 3 is an enlarged view of the vicinity of the contact portion between the roller 1 and the workpiece 4. In this state, the roller 1 is in contact with the clamper 3 and the workpiece 4. The driven rotation center 1c of the roller is above the point 2d where the curved surface of the lower mold 2 starts. This is the positional relationship immediately before processing, and the roller 1 cannot contact the workpiece 4 on the left side of this position in the drawing. That is, a non-machined area having a distance D is formed between the end surface of the clamper 3 and the roller contact point. In the known example described in U.S. Pat. No. 4,603,567, the rear roller 1 in this state is moved in the tangential direction of the curved surface of the lower die 2 (along the inclined portion of the upper surface of the clamper 3), and at the same time, in the normal direction thereof. Although a pressing force is applied by the above method so as to follow the curved surface of the lower mold, if the processing proceeds in this state, the state shown in FIG. 4 is obtained. Lower mold 2 and workpiece 4
There is a gap between the clamper and the work material between the tip of the clamper and the roller is elastically bent easily. If there is an elastic bending portion between the bending start point and the fixed point (clamper tip portion 3a), it becomes similar to that the workpiece 4 is held tilted with respect to the lower mold 2, and the amount of tilt is the material. It varies depending on the mechanical properties of. As a result, bending moments during processing, which are different from those at the start of processing, work sequentially on the bending part of the work material,
Forming does not consist of uniform bending. Therefore, the spring characteristics and dimensional accuracy of the molded product vary. Many of the radii of the resulting molded products are such that the radius of the molded product at the beginning of bending is much larger than the radius of the molded product in the middle.

Particularly, when the processing start point of the roller does not coincide with the lower mold curvature start point, the following is performed.

First, when the processing start point 1a of the roller 1 is on the clamper side of the lower die curvature start point 2b as shown in FIG. 5, elastic deformation is possible by the distance D1 as compared with the case where both start points coincide. The area becomes longer. This is because the actual bending process starts when the roller passes through the lower mold curvature start point 2d. At that time, the longer the distance between the work piece between the clamper tip portion 3a and the roller 1 (the larger the radius of the roller 1), the greater the rate of elastic deformation.

Next, as shown in FIG. 6, the processing start point 1 of the roller 1
When a is located on the tip side of the work piece from the lower mold curvature start point 2d, the position where the roller 1 contacts the work piece 4 is the position at which the bending moment is applied. That is, the bending process starts from the lower mold curvature start point 2b of the bottom surface of the clamper, not the tip portion 3a of the clamper. At first glance, this seems to accurately determine the bending start position, but in reality it is not. In this case, when a pressure is applied to the roller along the clamper, the processing start point 1a of the roller is determined by sandwiching the work material with the lower die. Since this point is naturally on the lower curved surface, the pressing force is not stable in the conventional method in which the pressure is not applied only in the normal direction of the curved surface. When the moving speed of the roller 1 is high, the applied pressure may be an impact load. Also,
Work piece 4 and roller 1 due to variations in plate thickness
(The distance between the bending start point of the workpiece 4 and the point where the roller 1 applies a force to the workpiece 4) changes. For these reasons, the bending moment applied to the bending start point of the work piece 4 is not constant, and the precision of the dimensions and spring characteristics of the molded product deteriorates.

[0009]

The above-mentioned prior art does not consider the following three points during bending.

(1) The starting position of bending (bending start position) is not particularly precisely determined, and bending is started. As a result, the shape of the molded product differs not only due to subtle individual differences such as the mechanical properties of the material but also due to changes in the bending moment due to variations in the bending start position, and its dimensional accuracy and spring characteristics vary during mass production. It was

(2) A gap is formed between the work piece and the lower die during processing. As a result, the molded products had different shapes, and the dimensional accuracy and spring characteristics varied during mass production.

(3) The bending roller is XY controlled and is not always pressed toward the center of the lower mold, and the pressing force changes during processing. As a result, dimensional accuracy and spring characteristics of molded products may vary during mass production.

The present invention solves these three problems and provides a leaf spring molding method in which the dimensional accuracy of the molded product and the accuracy of the spring characteristics are good.

[0014]

In order to solve the above problems, a roller having a notch at least at one location is used, and the notched end surface 1b is aligned with the clamper end surface and the bending start position is adjusted to form the roller. Solvable.

In order to solve the above-mentioned another problem, the bending roller can be always pressed down toward the center of the lower mold.

In order to solve the above-mentioned another problem, the workpiece 4 is fixed by the clamper 3 up to the position 2d where the curved surface of the lower die starts, and the position is set as the processing start position.

[0017]

The roller 1b having at least one cut-out portion can match the cut-out end face with the clamper end face 3a. As a result, as shown in FIG. 7, the end surface 3a of the clamper is
There is no unpressed portion between the roller 1b and the roller 1b, and the material 4 to be processed is bent without forming a gap between the material 4 and the lower die, and follows the curved surface of the lower die 2.

Further, by exerting a pressing force constantly on the center of the lower mold, there is an effect of making the lower mold normal direction force and the lateral force applied to the workpiece 4 of the roller 1b constant. As a result, the bending moment applied to the workpiece 4 becomes constant during bending, and the precision of the molded product is improved.

By fixing the workpiece 4 to the position 2d where the curved surface of the lower mold 2 starts with the clamper 3 and setting that position as the starting position for processing, the above two effects exert the maximum effect.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
This will be described with reference to 8 and 9.

FIG. 1 is a principle view of a method for forming a leaf spring according to the present invention, and is a longitudinal sectional view of a main part during bending. 7 is a principle view of the method for forming a leaf spring according to the present invention, which is a vertical cross-sectional view at the start of processing, and FIG.
FIG. Further, FIG. 9 is a vertical sectional view of an embodiment using this principle.

FIG. 9 shows the construction of an embodiment used in the method for forming a leaf spring.

A bearing 71 is fixed on the frame 7 and has a structure like a bearing member.
The inner peripheral side of the bearing 71 is rotatable, and the semi-circular member 72 that applies a pressing force to the roller 1 is a bearing 71.
It is rotatably attached in a plane parallel to the bearing 71 about a certain point. The semicircular member 72 has a roller 1b having a notch that is rotatably driven from the inner peripheral side toward the center of the bearing 71 via the load cell of the pressing force measuring means and the roller supporting member 12.
On the other hand, the lower mold 2 having a curved surface with a predetermined curvature used for bending
Is in the inner space of the bearing 71, and the bearing 71
The center of curvature and the bearing 7 so as not to interfere with the movement of
It is fixed on the frame 7 with the centers of 1 aligned. The semi-circular member 72 gives a force by a spring so as to always press the roller 1b toward the center of curvature of the lower mold 2 during processing, but the bending of the spring forming portion mounted slidably in the tangential direction of the outer periphery of the bearing 71. Actuator 1 of the sliding member 13 of the roller moving distance adjusting means for determining the angle
The pressure is adjusted to a predetermined value by 4.

The lower die 2 has a sunk taper pin which determines the fixing position of the work piece and the curved surface of the lower die. A hole made in the clamp portion of the workpiece 4 in advance enters this pin, the pin sinks, and the workpiece 4 and the lower die 2 can be precisely positioned.

A part of the material 4 to be processed is pressed against the lower mold 2 by the clamper 3 and held so as not to move during processing. The clamper 3 rotates the cam 15 by 180 ° by the rotational force of an actuator (not shown) fixed to the frame 7, and is brought to the position shown by the action of another actuator (not shown) and the link 16 to fix the workpiece 4. Further, after the processing is completed, the cam 15 is rotated by 180 ° by the rotational force of an actuator (not shown) fixed to the frame 7, and the clamper 3 is brought into the open position by the action of another actuator (not shown) and the link 16. It is attached to. The work material 4 can be moved in a direction perpendicular to the paper surface except during processing, and when the clamper 3 is opened, the next work material 4 can be supplied onto the lower mold 2. As a result, a plurality of workpieces 4 are fed in a direction perpendicular to the lower mold curved surface, and each workpiece 4 can be sequentially bent.

Although not shown, the shape and mechanical properties of the workpiece 4 before processing are measured, and the spring forming position of the workpiece 4 and the length of the spring forming portion are measured based on the measured values. The moving distance of the roller 1 that determines the load, the load cell for knowing the pressing force of the roller 1 before or during processing, and the actuator 14 for controlling the value so as to reach a preset pressing force are all Data processing and control are performed by an arithmetic and control unit (controller).

[0027]

By implementing the present invention, the processing conditions (bending moment) during bending can be kept constant, and the dimensional accuracy and spring characteristics of the molded product can be guaranteed with high accuracy.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention (bending state),

FIG. 2 is an explanatory view of the principle of the conventional method (processing start state),

FIG. 3 is an explanatory view of a contact state between a roller and a lower die and a work material,

FIG. 4 is an explanatory view of the principle of the conventional method (state during processing),

FIG. 5 is an explanatory view of a contact state between a roller and a lower die of a conventional method and a work material,

FIG. 6 is an explanatory view of a contact state between a roller and a lower die of a conventional method and a workpiece,

FIG. 7 is an explanatory view of the principle of the present invention (processing start state);

FIG. 8 is an explanatory diagram of a contact state between a roller and a lower die and a workpiece,

FIG. 9 is an explanatory diagram of an embodiment of the present invention.

[Explanation of symbols]

1 ... roller, 1b ... notched roller, 2 ... lower mold, 3 ...
Clamper, 4 ... Workpiece material.

Front Page Continuation (72) Inventor Kiyoji Morita 2880 Kozu, Odawara City, Kanagawa Hitachi, Ltd. Odawara Factory

Claims (3)

[Claims] 1. A part of a material to be processed is fixed by a clamper to a lower mold having a curved surface used for bending, and then a spring forming part of the material to be processed is continuously driven along a curved surface of the lower mold by a driven rotatable roller. In the method of forming a leaf spring that is pressed by force, a cylindrical roller having at least one notch is used. 2. The method of molding a leaf spring according to claim 1, wherein the notch portion of the roller is pressed against the tip end portion of the clamper to set the initial position of the roller. 3. The method for forming a leaf spring as claimed in claim 2, wherein the tip of the clamper is located on a plane including the center axis of curvature of the lower die and the center axis of driven rotation of the roller at the start of bending.