JPH0245964Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention relates to a terminal screw for a terminal that is often used in electrical equipment such as small switches and allows for contact with electric wires without using a cable eye or the like.

[Prior art and its problems] Conventional terminal screws of this type include, for example, No. 9 terminal screws.
The devices shown in FIGS. 1 to 12 are known. In the figure, the terminal screws are a tightening screw 10 and a screw 10.
It is composed of a square plate-shaped washer 20 fitted together with a spring washer 21. Tightening screw 10
A screw head 1, a threaded part 3 extending from the screw head 1 through a narrow diameter part 2, and a collar 4 provided near the threaded part 3 of the narrow diameter part 2 and having a diameter D1 slightly larger than the threaded part 3. It is equipped with On the other hand, the washer 20 is a square flat plate made of steel plate, and the diameter D of the flange 4 of the screw 10 is in the center.
A through hole 11 with a diameter D2 slightly smaller than 1 is bored. And on the lower surface side, a protrusion 12 extending from each of the four sides of the square toward the center of the through hole 11.
is provided. This protrusion 12 is extruded from the upper surface side of the washer 20 so that it has a rectangular cross-section and a so-called wedge-like shape in which the height increases successively from the center side to the four edges. The washer 20 can be fitted into the screw 10 by fitting and inserting the spring washer 21 into the screw 10, then inserting the washer 20 and driving it into the flange 4.
This can be done by passing through the through hole 11 while deforming it.

This type of terminal screw is subject to regulations such as UL standards. One test is to insert a connecting wire into a terminal, wind it around a screw, tighten the screw 10 with a constant torque, and then pull out the connecting wire. However, the terminal screw with this configuration has a protrusion 1 of the washer 20.
As mentioned above, since the shape of No. 2 is wedge-shaped with a rectangular cross section, the amount of penetration into the wire changes depending on the position where the connecting wire is inserted and wound (the size of the winding diameter). Even with the same tightening torque, it is not possible to obtain a uniform pulling speed, which means there is a lot of variation, and if the tightening torque is too high, the wire may break, so the tightening torque must be adjusted. There was a drawback that it was difficult to ensure the reliability of the connection state only by controlling the tightening torque.

[Purpose of invention]

The purpose of this invention is to eliminate the above-mentioned conventional drawbacks, eliminate the risk of disconnection of the connected wire under a specified tightening torque, increase the pulling force, and ensure stable and reliable connection with less variation. Our goal is to provide high terminal screws.

[Key points of the idea]

The key points of this invention are, in order to achieve the above-mentioned purpose, to use a head-mounted tightening screw with a narrow diameter section in the middle, and a spring washer that is loosely fitted into the narrow diameter section so that its movement is restrained in the axial direction. A terminal screw comprising a washer in the form of a square flat plate, and a wedge-shaped protrusion is provided on the upper surface side of the washer, extending from each of the four sides of the outer edge to the inside of the outer diameter of the screw head and being higher on the outside. , the above-mentioned protrusions are arranged 2 times on each of the four sides.
Each strip is provided with a trapezoidal cross-sectional shape, and they are spaced at intervals more than twice the width of the protruding strips, so that when the tightening torque of the tightening screw is excessive, it can be pulled out without cutting. The goal is to increase the amount of information and reduce variation.

[Example of idea]

Figures 1 to 8 are views showing an embodiment of the terminal screw according to this invention, and in the figures, the
The same parts as those of the conventional type in the figures are given the same reference numerals to correspond, and the differences will be explained. This embodiment is different from the conventional type in that two protrusions 13 are provided on each of the four sides of the washer 20 on the lower surface side, and the cross-sectional shape thereof is trapezoidal. To explain in detail, first, the trapezoidal cross-sectional shape of the protrusions is not symmetrical, and the inclination to the plane perpendicular to the bottom surface is 30 degrees on the inside (opposite side) of the two ridges, and 15 degrees on the outside. Next, the width E of the top side of the protruding ridge 13 and the distance L between the two ridges
is L/E>2, and the height H of the protrusion (the highest point on the outside) and the width E of the top side are each selected to have a relationship of E/L=0.5 to 1. As mentioned above, each protrusion 13 is formed such that the outer edge of the washer is higher and the inner side is lower so that H>K, and the connecting wire is connected to the screw 10.
When the wire is tightened, an inward force is applied, and as the diameter of the connecting wire increases, the bite becomes deeper. These dimensions and shapes are the result of repeated experiments and are based on the difference in strength between the steel material used for the washer 20 and the steel material constituting the connecting wire 30. In other words, in the case of L/E≦2, the connection wire 30 is overwhelmingly disconnected due to pulling out, and the cross section is made into the trapezoid mentioned above, and the height H and width E are set to H/E.
By setting the value to 0.5 to 1, the screw 10 has better bite when tightening, and stress concentration is reduced, so that the pulling force of the connecting wire 30 is significantly increased and variation is reduced. The above results are compared with the conventional type in FIG. 8, where the horizontal axis shows the tightening torque T of the screw 10, and the vertical axis shows the pulling force P of the connecting wire 30. As is clear from the figure, between the two, the pull-out force was increased approximately twice, and the variation was reduced by half. Therefore, the fear of breakage is eliminated, and only by controlling the tightening torque of the screw 10, including automation of assembly, a connection state with reduced variation and enhanced pulling force can be obtained.

[Effect of idea]

According to this invention, protrusions are provided on the lower surface of the square flat washer extending from each side of the outer edge, the cross-sectional shape is trapezoidal, and the protrusions are arranged in pairs at intervals of at least twice the width. By setting
It is possible to provide highly reliable terminal screws with reduced variation and increased connection strength simply by controlling the tightening torque.

[Brief explanation of the drawing]

Figures 1 to 8 show an embodiment of the terminal screw according to this invention, in which Figure 1 is a side view showing a cross section of the main part, Figure 2 is a rear view of the main part, and Figure 3 is a view similar to that shown in Figure 2. 4 is a plan view of the main part, FIG. 5 is a sectional view taken along the - line in FIG. is the 6th
8 is a diagram showing the effect of the embodiment, FIGS. 9 to 12 show an example of a conventional terminal screw, FIG. 9 is a side view showing a cross section of the main part, and FIG. 1
0 is a plan view of a main part, FIG. 11 is a side view showing a partial cross section of FIG. 10, and FIG. 12 is a sectional view taken along the line - in FIG. 10. 1...Screw head, 2...Small diameter portion, 10...Tightening screw, 13...Protrusion, 20...Washi, 21...
Spring washer.

Claims (1)

[Claims for Utility Model Registration] 1. A head-mounted tightening screw having a narrow diameter portion in the middle, and a square flat plate that is loosely fitted into the narrow diameter portion together with a spring washer so that its movement in the axial direction is restricted. A terminal screw having a wedge-shaped protrusion that is perpendicular to the four sides on the lower surface side of the washer, extends to the inside of the outer diameter of the screw head, and is higher on the outside. A terminal screw characterized in that two threads are provided on each of the four sides of the washer, and the cross section thereof is formed into a trapezoid. 2. A terminal screw as set forth in claim 1 of the utility model registration claim, characterized in that the distance between the protrusions on each side of the washer is at least twice the width of each protrusion.