JPH0151440B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention was provided in order to further improve the safety of a pantograph type jack, and at the same time, it simplifies the structure and contributes to cost reduction. First, to explain the conventional example shown in FIG. 1, a pantograph type jack is generally constructed by combining four arms to form a parallelogram link structure, and then combining a threaded rod thereto. That is, in the figure, a threaded rod 1 having a threaded portion 1c, a threaded rod receiver 2 through which the threaded rod rotatably passes, an arm 4 pivotally connected to the threaded rod receiver 2 via a pin 3, and a threaded rod. The handle joint 7 is composed of a thrust bearing 5 disposed in close contact with the receiver 2, a small diameter portion 6 formed at the end of the threaded rod 1, and a handle joint 7 having a U-shaped cross section.
A small diameter portion 6 passes through the handle joint 7, and a handle joint 7 is welded to the small diameter portion 6. Furthermore, recently, the through hole in the small diameter portion 6 of the handle joint 7 has been abolished, and a more reliable joining method using friction welding has been used. Furthermore, the handle joint 7 has an engagement hole 7 for a crank-type handle (not shown).
a and an engaging groove 7b are provided.

If the jack has such a structure, the large tensile force generated on the threaded rod 1 due to the jack load will act on the handle joint 7 via the thrust bearing 5, which will cause a large shearing force to be applied to the welded part 8. The welded portion may eventually break due to the load, resulting in a serious accident such as a heavy object falling while being lifted.

The present invention has been provided with attention to such points, and the embodiments shown in FIGS. 2 to 8 will be described below. In FIGS. 2 to 8, members having the same structure as in FIG. 1 perform the same functions as in FIG. 1, so illustration and description thereof will be omitted.

The enormous tensile force generated on the threaded rod 1 due to the load of the jack is received at the end of the threaded rod via the bearing. A method of dealing with this by providing a disk-shaped flange part by plastic working is already known, for example in Japanese Patent Application Laid-Open No. 48-9461, but a U-shaped handle joint is used. , as described above, is fixed to the threaded rod by welding or caulking. Here, the force applied to the handle joint is only the rotational torsion force due to arm strength applied through a commonly used crank-type handle (description omitted). The present invention has focused on this point, and by welding the flat handle joint 9 as shown in FIGS. It was possible to reduce the size of the parts to about one third of the conventional U-shaped handle joint 7 shown in FIG. 2, and to provide a threaded rod 1 with appropriate strength.

Usually, the disk-shaped flange portion is formed by header processing or the like, but in this case, the outer diameter of the disk-shaped flange portion is limited by the diameter of the threaded rod material, and it is difficult to make it large. The present invention has also focused on this point, and as shown in FIGS. 3a and 3b, the central part of the outer surface 1b of the disk-shaped flange part is concavely formed to form a concave concave part 10, so that the flow of material during flange forming is improved. We succeeded in improving the flange diameter and increasing the outer diameter of the flange. Note that it is preferable that the concave recess 10 has a substantially conical shape.

Furthermore, since the threaded portion of the threaded rod 1 is generally formed by rolling, the outer diameter of the non-threaded portion 1d is smaller than the outer diameter of the threaded portion 1c, as shown in FIGS. 4a and 4b. . When assembling a jack, the thrust bearing 5 is usually inserted into the threaded rod 1 with the disk-shaped flange portion 1a formed after the screw is rolled, and the outer diameter of the screw is larger than the diameter of the threaded rod at the bearing abutting portion. Since the difference is large, the thrust bearing and the shaft will play due to the difference, causing eccentricity of the thrust bearing, and an uneven load will be applied to the thrust bearing. This also causes a bending effect on the threaded rod, which has a very harmful effect.

In the embodiment shown in FIG. 4, at the same time as the disc-shaped flange portion 1a is formed, at least three protrusions 1e are formed on the outer circumference of the root shaft of the threaded rod, which is the bearing abutting portion. It was possible to assemble the threaded rod without play. Note that the length of the protrusion 1e may be long, but a length of 2 to 3 mm is sufficient. In addition, normally the flange root 1f is the bearing inner circumferential corner 1g.
However, by providing the projection 1e and aligning the center of the bearing and the shaft, it is possible to add a larger radius to the flange root 1f except for the projection 1e. In forming the disk-shaped flange portion 1a described above, it has become possible to obtain a flange with a larger outer diameter.

Although arc welding may be used to connect the outer surface 1b of the disc-shaped flange portion to the flat handle joint 9, resistance welding is preferred as it is more economical.

In the embodiments shown in FIGS. 5a and 5b and 6a and 6b, a protrusion 1h is provided on the outer surface 1b of the disc-shaped flange portion in order to obtain a stable welded connection by resistance welding. This protrusion 1h may be formed only at the abutting portion of the flat handle joint 9, but it may be formed into a disk shape as shown in FIG. 6 or by providing a concave recess on the outer surface 1b of the flange portion as shown in FIG. It may be a protrusion 1j that is formed. Furthermore, as shown in FIGS. 7a, b and 8a, b, by providing the groove-like notch 1i of the handle joint fitting part in the diametrical direction on the outer surface 1b of the disc-shaped flange part, the reliability of the bonding strength is improved. We were able to further improve this.

In this way, in the present invention, the required strength of each part of the threaded rod was analyzed, and the end of the threaded rod was made into a disc-shaped flange, which created a saucer for welding and joining, thereby improving the handle joint. The welded joint area has become larger, making it stronger and able to withstand large shear forces. This structure can be made even stronger to withstand shearing force by providing recesses, protrusions, or groove-like notches in the disc-shaped flange part, and has a necessary and sufficient lightweight and compact shape. In addition, ordinary small machines are sufficient for forming the disc-shaped flange part and for manufacturing and joining the handle joint, without using special machines such as friction welders, and these parts can be manufactured easily. The press molds and jigs needed to do this were small and inexpensive, and by incorporating threaded rods with these excellent features, it became possible to provide a pantograph type jack with a simpler and more economical structure. .

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of the handle joint of a conventional pantograph jack; Fig. 2a is a side view showing the handle joint welded to the end of the threaded rod according to the present invention; Fig. 2 b
is a front view of the same. 3 to 8 are views of the threaded rod end portion showing other embodiments, in which a is a side view and b is a front view. 1...Threaded rod, 1a...Disk-shaped flange part, 1
b...Outer surface of the disc-shaped flange part, 1c...threaded rod threaded part, 1d...threaded rod unthreaded part, 1e...threaded rod projection part, 1f...root part of the disc-shaped flange part, 1
g...Bearing inner circumference corner, 1h...Protrusion, 1i...
groove-shaped cut portion, 1j... disc-shaped protrusion, 5... thrust bearing, 9... flat handle joint,
10...Concave depression.

Claims (1)

[Claims] 1. A substantially disk-shaped flange portion 1a formed by plastic working is provided at one end of the threaded rod 1, and a flat handle joint 9 with a hole formed approximately in the center is attached to the outer surface 1b of the disk-shaped flange portion. A pantograph type jack that is welded together in an upright position. 2. The pantograph type jack according to claim 1, wherein the disk-shaped flange portion 1a has a concave recessed portion 10 formed in the center of its outer surface. 3. The pantograph type jack according to claim 1, wherein the disc-shaped flange portion 1a has at least three protrusions 1e formed on the outer periphery of its root shaft. 4. The pantograph type jack according to claim 1, wherein the disc-shaped flange portion 1a is provided with a protrusion portion 1h on its outer surface. 5. The pantograph type jack according to claim 1, wherein the disc-shaped flange portion 1a is provided with a groove-shaped cutout portion 1i in the diametrical direction on its outer surface.