JPH03172633A - Helical spring - Google Patents

Abstract

PURPOSE:To make the spring stand a large load and reduce the natural frequency under loaded condition by making the shape of the spring helical so that adjacent parts are not overlapped in plane view, the width of any part is sufficiently large relative to the thickness, and the width is increased approximately proportional to the distance from the axis. CONSTITUTION:A helical spring 10 is made to that adjacent parts are not overlapped in plane view and the cross sectional width B of any part of the spring is sufficiently large relative to its thickness. Assuming the width at the reference point A as B and the gap as C, the relationship at a position of an angular distance theta from the reference point A is (B+C)=(BO+C)exp(lambdatheta), where lambda is a factor. Namely the width B is an exponential function of the angular distance. With this constitution, the helical spring is less vulnerable to buckling, stresses are made uniform, and a large load may be applied. Also the natural frequency of the spring becomes low to show a characteristic similar to that of an air spring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a helical spring, particularly one whose planar shape is spiral.

[Prior Art] Conventionally, there is a conical helical spring in which each part has the same circular cross section, but it has the disadvantage that it is easily buckled and that stress is not generated uniformly in each part in response to a load. Also,
Conventionally, a spiral spring has been used in which each part has the same rectangular cross section and is arranged in a flat spiral shape, but this utilizes elasticity with respect to the rotation angle between the center and outer ends. Also,
Conventionally, in order to support a large load with a spring having a small spring constant to achieve a low natural frequency, such as within 1Hz, it was necessary to use an air spring, which was expensive.

[Problem to be Solved by the Invention 1] The present invention is designed to resist buckling, generate uniform stress in each part in response to a load, and withstand a large load, and furthermore achieve a low natural frequency while supporting the load. To provide an inexpensive helical spring that can be

[Means for Solving the Problems] This invention has a rectangular cross section whose planar shape is a spiral that does not overlap with adjacent parts, has a substantially constant thickness, and whose width is sufficiently long compared to the thickness. The present invention provides a helical spring characterized in that the width is approximately proportional to the length from the central axis to that portion.

[Examples] Examples of the present invention will be described below with reference to the drawings.

In one embodiment of the invention shown in FIGS. 1 and 2, 1
0 indicates a helical spring according to the invention. The helical spring has a spiral shape as a whole and does not overlap with adjacent parts. This helical spring is constructed by cutting a single spring metal plate, and each part has a constant thickness and is sufficiently thin compared to its width. This helical spring is as shown by equations (1) and (2) using the following symbols.

0: Central axis A: Base point R: Length from the center axis of any part Ro Length from the central axis at two base points B: Width of any part Bo Width at two base points C: Cut width: Arbitrary coefficient (for example, a small value such as 0.01 or 0.02) θ: Rotation angle from the base point R=Ro exp (Eθ)−・−−−(1)(B+C
)= (Bo +C)exp (nθ)...
・ ・ (2) Here, exp (nθ) means e to the 0th power. In other words, each portion of the helical spring increases in length from the central axis to the base point A as an exponential function of the rotation angle from the base point. Furthermore, when the cut width C is constant and smaller than the width B, the width B is also approximately the width B at the base point from equation (2). , the rotation angle from the base point increases to become the same exponential function as the above-mentioned exponential function of the rotation angle from the base point. Since the width B of this helical spring is sufficiently narrow compared to the thickness, the spring constant is small and the spring is elastic. Also, ignoring the influence of the slope of each part due to the pitch P, When width C is ignored, the maximum shear stress of each part is approximately expressed by equation (3) using the following symbols.

t: Thickness F: Load τ: shear stress 2t2 B.

In other words, it is completely unrelated to the rotation angle θ of each part. Therefore, the stress in each part becomes uniform and a high load can be applied.

In other embodiments of the invention shown in FIGS. 3 and 4, the case where the cut width C is zero is shown, and the equation (1) and C
This is based on equation (2) where =0. In order to manufacture such a helical spring, a single spring metal plate can be used most effectively.

In each of the above embodiments, the cases where the cut width C is smaller than the width B of each part or zero are illustrated and explained, but the cut width C has a size that cannot be ignored compared to the width B. For example, it may be increased so as to become an exponential function of the rotation angle from the base point A similar to equation (1). In such a case, the width B may be increased independently so that it becomes an exponential function of the rotation angle from the base point A, similar to equation (1).

Furthermore, the present invention can also be applied to a structure having a general spiral planar shape other than an exponential shape as shown in equation (1). In such a case, the width B may be changed in proportion to the length R of each portion from the central axis O. Any shape may be used as long as the cut width C is greater than zero and there are no overlapping parts, and any shape that can be manufactured from a single spring metal plate is sufficient.

5 and 6 show a state in which a supported body 90 is supported on a support body 91 using a plurality of helical springs IO according to the present invention. By using a helical spring 10 that is sufficiently long in the vertical direction when not under load, the natural frequency can be made sufficiently small not only in the vertical direction but also in the horizontal direction. You can rub it within the number.

7 and 8 show a state in which a supported body 90 is supported by a support body 91 using a plurality of sets of helical springs 10 according to the present invention, one of which is upside down and connected by a connecting rod 12. . By stacking them in this way, a small device can withstand heavy loads, and the natural frequencies in the vertical and horizontal directions can be significantly reduced.

FIG. 9 and FIG. 1O show a state in which a supported body 90 is supported on a support body 91 using a plurality of helical springs 10 according to the present invention. 13 is a column extending downward from the supported body 90; 15 is a frame having a hole 16 through which the column can be moved horizontally; a helical spring 10 is connected between the frame and the lower end of the column 13; The 0-string spring lO, which is horizontal under no load or in the opposite direction to that shown in the figure, extends to the state shown in the figure due to a load. This usage example allows the supported body 90 to vibrate in the horizontal direction in a stable manner.

[Effects of the Invention] Since the present invention is constructed as described above, it is difficult to buckle (the stress is uniform and a high load is applied, and the spring constant in the axial direction and the direction transverse to this is small, so that the load is not easily buckled). In the supported state, the natural frequency can be set to be low, for example, IHz or less, and it has the effect that the same characteristics as an air spring can be obtained with an inexpensive metallic spring.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing one embodiment of the present invention, Fig. 2 is a longitudinal sectional view thereof, Fig. 3 is a plan view showing another embodiment of the invention, and Fig. 4 is a longitudinal sectional view thereof. Fig. 5 is a front view showing the present invention in use, Fig. 6 is an enlarged view of a part thereof, Fig. 7 is a front view showing another use state of the invention, and Fig. 8 is a detailed view of the part. , FIG. 9 is a front view showing another state of use of the present invention, and FIG. 1O is a detailed view showing a part thereof in cross section. 10 is a helical spring, 0 is the center axis, A is the base point, B is the width, C
is the cut width.

Claims (1)

[Claims] 1. The planar shape is a spiral that does not overlap with adjacent parts, the thickness is almost constant, and the width is a sufficiently long rectangular cross section compared to the thickness, and the width of each part is the length from the central axis to that part. A string-wound spring characterized by being approximately proportional to the length of the spring.