JPH0417544A - Machining method for screw hole for grounding terminal of casting component - Google Patents

Abstract

PURPOSE:To disperse with a marking operation on the occasion of machining a screw hole, by providing a material with grooves crossing each other in the shape of the cross while forming a round hole at a point of intersection of these grooves and by machining the screw hole with the point of intersection of the grooves or the round hole used as the center of a lower hole. CONSTITUTION:A seat 6 for fitting a grounding terminal not shown in the Figure is formed in projection on the inside of a bracket 1 and a screw hole 5 is machine in the center of this projecting seat 6. Grooves 3 each having a U-shaped section and being about 1mm wide and deep are formed in the fore end face of the projecting seat of a material 2 so that they cross each other in the shape of the cross, and a round hole 4 being wider and deeper than the grooves, in short, is formed at a point of intersection of these grooves 3. The point of intersection of the grooves 4 or the round hole 4 is used as the center of a lower hole of the screw hole 5, and the lower hole and the screw hole 5 are machined with either of them used as the center. According to this constitution, not only a marking operation is dispensed with, but also run-off of the fore end of a drill on the occasion of machining the lower hole is prevented, and besides the center of the seat can be aligned easily with the center of the screw hole when the central part of the projecting seat is machined.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a processing method that enables the processing of screw holes for ground terminals that do not require positional accuracy of cast parts without the need for drilling work.

[Conventional technology]

When drilling a screw hole for a ground terminal in a cast part, generally first mark the center position of the pilot hole on the material based on the drawing, dent it with a punch, and then use this as the center to drill the pilot hole and the screw hole. I was trying to process it.

[Problem to be solved by the invention]

Not only does the above method require a lot of work to drill, but the unevenness of the surface of the casting material makes it easy for the tip of the drill to slip away when drilling the pilot hole, and when making a screw hole in the center of the protruding seat, the accuracy of the casting is compromised. If the position of the seat deviates within the allowable accuracy range, the center of the seat and the center of the screw hole may deviate to an extent that can be seen at a glance, resulting in an unsightly appearance.

In order to eliminate the above-mentioned drawbacks, the present invention provides a method for machining a screw hole for a ground terminal in a cast part, which allows the screw hole for a ground terminal that does not require positional accuracy to be machined without scribing. The purpose is to

[Means to solve the problem]

In order to achieve the above object, the present invention provides narrow cross-shaped grooves 3 in the material 2 of the cast part 1, and if necessary, forms a suitable round hole 4 at the intersection of the grooves 3. In this method, the threaded hole 5 is machined using the intersection of the grooves 3 or the round hole 4 as the center of the pilot hole.

[Effect]

By using the round hole 4 at the intersection of the grooves 3 as the center of the pilot hole, marking work is not only unnecessary (it also prevents the tip of the drill from escaping when drilling the pilot hole, and also allows the screw hole 5 to be placed in the protruding seat). 6, the center of the seat 6 and the center of the screw hole 5 can be easily aligned.

〔Example〕

1 to 6 show embodiments of the present invention. These figures show a cast metal bearing bracket (cast metal part) for a rotating electric machine and its material 2, and a seat 6 for attaching a grounding terminal (not shown) is formed protruding from the inner surface of the bracket 1.
A screw hole 5 is machined in the center of this protruding seat 6. Narrow grooves 3 with a width and depth of approximately 1 mm, each having a U-shaped cross section (a ■-shaped cross section is also acceptable), are formed on the tip surface of the protruding seat of the material 2, crisscrossing each other in a cross shape. This will form a suitable round hole 4 that is wider and deeper than the groove 3. The intersection of the grooves 3 or the round hole 4 is used as a pilot hole center for the screw hole 5, and the pilot hole and the screw hole 5 are machined using these as centers.

According to the above-mentioned embodiment, not only does the drilling work described in the conventional technique become unnecessary, but also the tip of the drill is prevented from escaping when drilling the pilot hole, and the center of the seat 6 and the center of the screw hole 5 can be easily aligned. You can also do it.

Although the case of the bracket 1 has been described in the above embodiment, the present invention is not limited to this. The present invention is also useful when applied to drill holes, screw holes, etc. other than the ground terminal screw hole 5, which do not require positional accuracy.

〔Effect of the invention〕

According to the present invention, in the method of machining a screw hole for a ground terminal in a cast part, narrow cross-shaped grooves are provided in the material of the cast part, and if necessary, a suitable round hole is formed at the intersection of the grooves. Since the threaded hole is machined using the intersection of the grooves or the round hole as the center of the pilot hole, it not only eliminates the need for the sharpening work described in the conventional technology, but also prevents the tip of the drill from running out when drilling the pilot hole. In addition, when processing the center of the protruding seat, the center of the seat and the center of the screw hole can be easily aligned.

[Brief explanation of drawings]

Fig. 1 is a front view of an embodiment of the invention, Fig. 2 is a longitudinal sectional view of Fig. 1, Fig. 3 is an enlarged front view of the main part of Fig. 1, and Fig. 4 is a longitudinal sectional view of Fig. 3. , Figure 5 is a front view after processing of Figure 1,
FIG. 6 is a longitudinal sectional view of FIG. 5. 1... Casting part, 2... Material, 3... Groove, 4...
・Round hole, 5...screw hole. Figure 1 Figure 2 Figure 5 Figure 6

Claims (1)

[Claims] 1) Provide narrow cross-shaped grooves in the material of the cast part, and if necessary, form a suitable round hole at the intersection of these grooves, and use the intersection of the grooves or the round hole as the center of the pilot hole to insert a screw hole. A method for machining screw holes for ground terminals in cast parts.