JPH02129402A - Sheet metal connection by screw in cooking machine - Google Patents

Abstract

PURPOSE:To prevent a screw from losing its effect because of expansion of a burring diameter when another part is attached to a sheet-metal-made-part through screw connection by forming the burring part at the top of an indentation having a conical or spherical shape. CONSTITUTION:A tap tightening screw 13 is screwed through self-tapping to a burring part 14 of a sheet metal body 11 via a hole 16 made in a resin body 12. When torque is applied to the screw, the sheet metal body 11 is subjected to the force in the B-direction. In this case, however, since a burring part 14 of the sheet metal body 11 is formed at the top of an indentation 15 having a conical shape, the force in the B-direction is dispersed as the force in the direction, which reduces the diameter of the burring part 14. Accordingly, the burring part 14 tends to tighten the threaded part of the screw 13, thereby preventing the screw 13 from losing its effect.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for screwing thin sheet metals used in cooking machines and the like.

BACKGROUND OF THE INVENTION Conventional screw connections between so-called thin sheet metal and other parts, such as the outer shell of a cooking machine, are as shown in FIGS. 7 and 5.

For example, in the case of a screw connection between the sheet metal bore 1 and the resin body 2, the burring part 3 is entirely formed on the sheet metal body 1, and the resin body 2
A tag tie 1 to a screw 5tjtM is inserted into the hole 4, and the burring portion 3 of the sheet metal body 1 is tightened with the screw.

However, with this type of structure, tap-tight screws [
If the tightening of 5 is made a little stronger, the self-tapped screw thread of the burring part 3 of the sheet metal body 1 may be deformed, causing screw looseness.This is for the following reason.

In other words, tap tight screw 6', yJ4 fat body 2
4 kA and insert it into the bar ring part 3 of the sheet metal body 1, the screw is tapped while self-tapping the inner diameter metal of the bar ring part 3, and advances until the screw head of the tight screw comes into contact with the resin body 2, and at this time. , the propulsion torque of the screw increases at pj. At this time, it can be determined that the screw connection has been completed. However, when the hole 4 of the resin body 2 is larger than the screw diameter, the part of the claw sheet metal body 1 that is not in contact with the resin body 2, that is, the outer circumference of the burring part 3 of the sheet metal body 1, is damaged in the axial direction (input direction) by tightening the screw. ), and even after screw tightening is completed, the screw is deformed with a force comparable to the screw's propulsion torque, so the inner diameter of the burring part expands and the screw thread deforms and breaks before it is possible to determine whether screw tightening is complete, causing the screw to become damaged. It was to be.

Therefore, the present invention is designed to self-tap a thin sheet metal so that even when the screws are fully tightened, the sheet metal will not be deformed by a force comparable to the driving torque for screw tightening.

A means for solving the problems and a technical means of the present invention for solving the above-mentioned problems is that the periphery of the burring portion of the thin sheet metal is lowered one step in a conical or spherical shape.

action The effect of this technical means is as follows.

That is, when the screw head comes into contact with the resin body and screw tightening is completed, a force acts on the sheet metal body to deform it in the axial direction, as in the conventional example. However, since the outer periphery of the burring part is lowered one step in a conical shape, when it is deformed in the axial direction, a force acts to reduce the inner diameter of the burring part. Therefore, the force that bites into the screw acts to increase the breaking strength.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

In FIGS. 1 and 2, reference numeral 11 denotes a sheet metal body made of thin sheet metal, and a resin body 12 is fitted around the outer periphery of this sheet metal body 11 and fixed at several locations with taptight screws 13. To explain this screw tightening part in detail, a burring part 14 having an inner diameter smaller than the thread diameter of the taptight screw 13 is formed in the sheet metal body 11 at the apex of a recess 16 that is conically or spherically recessed from the surface of the sheet metal body 11. 1, and the outer diameter of this recess 16 is the same as that of the resin body 12.
The diameter is set to be approximately the same as the diameter of the hole 16.

A hole 16 is formed in the resin body 12, and the hole diameter is larger than the thread diameter of the taptight screw 13.

Generally speaking, this diameter must be made larger as the number of screws tightened increases to absorb dimensional deviations between pitches.

Next, the operation of the configuration of this embodiment will be explained. The taptight screw 13 is passed through the hole 16 of the resin body 12 and self-tapped to the burring part 14 of the sheet metal body 11 to perform screw tightening, and when the screw head 17 comes into contact with the resin body 12, the screw tightening is completed. Further, when a rotational force is applied to the screw, a force is applied to the sheet metal body 11 in the axial direction (direction B). However, since the burring part 14 of the sheet metal body 11 is formed at the apex of the conical recess 15, the force in the axial direction (direction B) is applied to the center direction C direction of the burring part 14,
That is, the force is dispersed in a direction that reduces the inner diameter of the burring portion 14. Therefore, the burring part 14 is fully tightened at the threaded part of the taptight screw 13, and as in the conventional example, the inner diameter of the burring part 14 expands due to the deformation of the sheet metal body 11 due to the axial force of the screw, which is equal to the driving torque of the screw. There is no possibility that screw looseness will occur due to a certain degree of rotational force.

Next, another embodiment of the present invention will be described. FIG. 3 shows another embodiment, in which the sheet metal body 1
A hole 19 smaller than the thread diameter of the Taptight screw 13 is provided at the apex of the 16° recess of the hole 1, and the Taptight screw 13 is tightened in this hole 19. This configuration also provides the same effects as those of the above-mentioned embodiments, and has the effect that the sheet metal body 11 can be easily processed.

Effects of the Invention As is clear from the description of the embodiments described above, the present invention provides a method for connecting a burring part of a sheet metal part made of thin sheet metal with a conical or spherical recess when another part is screwed to the burring part. Because it is formed at the apex, even after screw tightening is completed, the sheet metal part will not be deformed by the same rotational force as the screw's propulsion torque, the burring diameter will expand, and screw looseness will not occur.

Furthermore, since there is a large difference between the torque when the screw is being propelled and the torque when screw tightening is completed, there is also the effect that it is possible to reliably determine whether screw tightening is complete.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of the main parts showing a cooking machine according to an embodiment of the present invention, Fig. 2 is an enlarged view of the same, Fig. 3 is an enlarged view of the main parts showing another embodiment of the invention, and Fig. 4 is an enlarged view of the main parts. The figure is a vertical cross-sectional view of a main part of a conventional cooking machine, and FIGS. 5a and 5b are enlarged views of the same. 11...Sheet metal body 12...Resin body 13...Tap tight screw% 14...
... Burring part, 16... Conical depression. Name of agent: Patent attorney Shigetaka Awano and 1 other person
--42! Gold:r:F- Figure (OJ) (b)

Claims (2)

[Claims] (1) A thin sheet metal part having a cylindrical hole formed therein and a screw for connecting other parts to the cylindrical hole, the cylindrical hole being arranged at the apex of a conical or spherical recess in the thin sheet metal part. A screw connection method for thin sheet metal such as machines. (2) The method of screwing together thin sheet metals for cooking machines and the like according to claim 1, wherein the hole is arranged at the apex of the conical or spherical recess of the thin sheet metal component.