JPS6020273Y2 - Tube cap - Google Patents

Description

[Detailed description of the invention] This invention is a tube cap that integrates each half with screws.
This invention mainly relates to the improvement of caps used in ring-shaped discharge lamps.

Generally, as shown in Figs. 1 and 2, the current discharge lamp cap has a semicircular arc-shaped cap body 1 and a lid body 2 made of resin.
It has a structure in which each half of the cap is fastened with screws 3.

The base body 1, which is one half of the base, has a thick wall portion 4 in the center thereof, and four base pins 5 are inserted and fixed into the thick wall portion 4.

Further, a through hole 6 through which the screw 3 is passed is formed in the center of the thick portion 4.

In addition, there is a screw 3 in the center of the lid body 2, which is the other half of the cap.
A screw hole 7 is provided in which the lid body 2 is screwed, and after aligning the lid body 2 with the base body 1, the screw 3 is passed through the through hole 6 and screwed into the screw hole 7. A lid body 2 is fastened to 1.

By the way, the cap body 1 and the lid body 2 are usually made of thermosetting resin such as Yurya resin, but since the nature of the resin is hard, it is difficult to use self-tapping screws as the screws 3 for fastening. is difficult.

For this reason, the threads are cut during the molding of the cap, and although commercially available coarse thread screws can be used to fasten the cap, the thread cutting during the molding of the cap significantly impedes work efficiency. There was a drawback.

Furthermore, if the screws 3 are tightened too tightly, there is a risk that the outer shell parts of the cap body 1 and lid body 2 will crack, so in order to ensure sufficient mechanical strength, the wall thickness of these parts must be increased. Therefore, material costs were high, making it difficult to reduce costs.

The present invention improves and eliminates the above-mentioned conventional drawbacks, and provides a tube cap in which each half of the cap is made of thermoplastic resin and each half is fastened with a slit-shaped self-tapping screw. .

That is, the present invention uses a thermoplastic resin such as PBT (polybutylene terethalate) resin that has good heat resistance, light resistance, and chemical resistance to insecticides. For example, as shown in FIG. 3, the base body 8 and the lid body 9 are formed into halves.

This thermoplastic resin is flexible and mechanically strong, so the thickness of the outer shell portions 8 and 9 of the base body 8 and the lid body 9 may be thin, for example, about 1 mm.

Then, the cap body 8 and the lid body 9 are fastened together with a self-tapping screw 11 having a slit 10 in the axial direction from the tip of the screw.

In addition, 12 in FIG. 3 is a thick part of the base body 8, 13 is a through hole for screw insertion that penetrates the thick part 12, 14 is a base pin,
15 is a screw hole provided in the lid body 9.

As shown in FIG. 4, the slit 10 of the self-tapping screw 11 is provided with a force of, for example, 4 t relative to the cross-sectional area of the screw.

The axial length L of the slit 10 is longer than the length 1 of the tightening margin m screwed into the screw hole 15 of the self-tapping screw 11.

When the self-tapping screw 11 is provided with the slit 10 in this way, and the self-tapping screw 11 is inserted into the through hole 13 and tightened into the screw hole 15, the contact area between the self-tapping screw 11 and the screw hole 15 is the same as that without the slit 10. 1, it will be approximately 3 if there is a slit 10, and the tightening torque of the tapping screw 11 will be reduced by this decrease.

Further, since the lid body 9 is made of thermoplastic resin and has flexibility, there is almost no fear of damage even if the tapping screw 11 is tightened more than necessary.

In fact, the outer shell portion 8' of the cap body 8 and the lid body 9.

When the wall thickness of 9' was made simple, the tightening torque of the tapping screw 11 was preferably about 0.8 to 1.0 kg-am.

In addition, if the length of the slit 10 is made shorter than the tightening margin m of the self-tapping screw 11, the tightening torque at the final tightening will become too large as in the conventional case, and the groove of the screw head will be crushed. It becomes necessary to use it, which increases the cost.

Therefore, the length of the slit 10 must be sufficiently longer than the length of the interference portion m.

Further, since the tightening torque of the tapping screw 11 can be reduced by forming the slit 10, an inexpensive screw that is not hardened can be used, and costs can be effectively reduced.

The present invention is not limited to the cap for a ring-shaped discharge lamp, but can also be applied to caps for other types of discharge lamps, such as straight-tube discharge lamps.

As explained above, according to the present invention, the tightening torque of the tapping screw is reduced, so there is no damage to the cap or crushing of the head of the tapping screw itself, and stable automatic screw tightening is possible.

In addition, since each half of the cap is made of thermoplastic resin, its flexibility can be used to reduce the thickness of each half without worrying about damage due to force when tightening, reducing material costs. Moreover, since there is no need for thread cutting, it is actually possible to reduce costs by about 30% compared to conventional caps.

[Brief explanation of the drawing]

Figure 1 is a side sectional view of a conventional cap, Figure 2 is Figure 1 A-A
FIG. 3 is a cross-sectional view of essential parts showing an embodiment of the base according to the present invention, and FIG. 4 is an enlarged cross-sectional view taken along line B--B in FIG. 3. 8... Cap body (half piece), 9... Lid body (half piece), 10... Slit, 11...
・Tapping screw, m...Tightening allowance part.

Claims (1)

[Scope of utility model registration request] Each half of the cap is shaped with thermoplastic resin, and each half is made of
A tube cap characterized by being fastened with a self-tapping screw having a slit in the axial direction extending from the tip of the screw to a length longer than the tightening margin.