JPH0419032A - Reference pin with resistance against electric erosion - Google Patents

Abstract

PURPOSE:To prevent slackening and generation of wear and/or chipping resulting therefrom by forming an adhesive layer on the thread surfaces at a protrusion of the head of a reference pin, in which the head, intermediate part, and base are connected serially, and by providing the base with a recess in which part of the intermediate part is fitted tightly. CONSTITUTION:An electrical erosion resistant reference pin 1 consists of a head 2, an intermediate part 3 made of non-conductive material, and a base 4, which are connected serially. The head 2 has a protrusion 2a protruding toward the base 4 and equipped with threads 2b, wherein an adhesive layer 2c is formed on the surfaces of the threads 2b, and the intermediate part 3 has a through hole 3a penetrated by the protrusion 2a while the base 4 has a screw hole 4a to engage with the threads 2b on the protrusion 2a. Further the base 4 is provided with a recess 4b in which part of the intermediate part 3 is fitted tightly. Thus an electrical erosion resistant reference pin is obtained, wherein slack of mechanical components with one another is well precluded along with generation of wear and/or chipping resulting therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an electrolytic corrosion-resistant reference pin. More specifically, the present invention relates to an electrolytic corrosion-resistant reference pin used for positioning workpieces such as press parts.

[Prior Art] Conventionally, reference pins have been used in a wide range of industries to accurately hold workpieces in predetermined positions (for example, Japanese Utility Model Application Publications No. 62-29238 and No. 63-7).
(See Publication No. 4239).

The conventional reference pin 01) is, for example, SCH315 (SC
Chromium molybdenum MtlA materials (JISG
4105), 345C and other carbon steel materials for machine structures (J
Steel reference pins made of ISG 405] or the like are commonly used either as they are or after being hardened. Therefore, when used near the spot welding point for spot welding of conductive workpieces such as steel plates, the current flowing from the spot electrode will spark through the workpiece to the pin, resulting in electrolytic corrosion. There is a disadvantage that melting damage occurs on the pins.

As reference pins that avoid this drawback, reference pins with a ceramic layer formed on the surface (see Japanese Patent Application Laid-open No. 63126682) have been proposed, but as a reference pin with better electrolytic corrosion resistance, Reference pins such as those shown in FIGS. 2-3 are also conceivable, which combine metal and non-conductive materials such that the pins are non-conductive.

The reference pin 01) shown in FIG. 2 has a head Oz with a screw hole (12a), an intermediate opening with a through hole (13a) in the center, and a protrusion (1, 1) with a threaded part (14b). 4a
) and a protrusion (14a).
is formed by passing through the through hole (23a) and screwing into the screw hole (12a). As the material for the head (12) and the base (2), the above-mentioned carbon steel for mechanical structure is used, and as the material for the middle zone, a non-conductive material such as ceramic such as 513N4 is used.

However, this reference pin (II) easily gets caught in the boundary between the head (+21 and the base side), and as a result, the loosened head 02 in particular) and the intermediate part 03 when the workpiece is attached or detached. It is prone to wear and damage that may be caused by.

The reference pin (21) shown in FIG. 3 also has a similar configuration to that in FIG. a protrusion (24) with a middle part made of a flexible material and a threaded part (24b)
a), and the protrusion (24a) passes through the through hole (23a) and is formed by screwing into the screw hole (22a), and the threaded portion screwing into the screw hole (22a). (24b) is provided with an adhesive layer <24c). Further, as the material for the head and the base, alloy tool steel such as 5KDII (JIS G 4404), which has a higher hardness than carbon steel for machine structures, is used.

However, even in this reference pin (2υ), the threading between the head and the base (end) becomes loose, causing wear and damage at the boundary between the head and the intermediate part.

[Problems to be Solved by the Invention] The present invention has been made in view of the problems of the conventional electrolytic corrosion-resistant reference pins, and prevents the loosening of component parts and the occurrence of wear and damage caused by this. The purpose is to provide an electrical corrosion resistant reference pin.

[Means for Solving the Problems] The present invention provides a reference pin, which has a head, an intermediate portion made of a non-conductive material, and a base connected in series, and is used for positioning a workpiece, The head part has a protruding part in which a threaded part is formed protruding in the direction toward the base, an adhesive layer is formed on the surface of the threaded part, and the intermediate part has a through hole penetrated by the protruding part. The present invention also relates to an electrolytic corrosion-resistant reference pin in which the base portion has a tapped hole that engages with the threaded portion of the protruding portion, and the base portion further includes a recess portion into which a portion of the intermediate portion is tightly fitted.

[Function] The electrolytic corrosion-resistant reference pin of the present invention has a screw hole formed in the base. In general, the optimal dimensions of the head shape are limited due to the operability of attaching and detaching the processed product, whereas the dimensions of the base shape can be set relatively freely. Therefore, the threading length between the protrusion and the screw hole can be set to a sufficient length that does not cause loosening within the limit range of the jig for attaching the reference pin.

Further, since an adhesive layer is formed on the threaded surface of the protrusion, the threaded surface and the inner surface of the screw hole are firmly fixed.

Furthermore, since the base is formed with a recess into which a portion of the intermediate portion is tightly fitted, by tightening the protruding portion into the screw hole, the intermediate portion is press-fitted into the recess, and the intermediate portion, base, and head are pressed into place. There is no looseness between the parts, and the effect of preventing loosening, wear, and chipping is even more reliable.

[Example] Next, an example of the electrical corrosion resistant reference pin of the present invention will be described based on the drawings.

FIG. 1 is an explanatory diagram showing an example of the electrical corrosion-resistant reference pin of the present invention.

As shown in FIG. 1, the electrical corrosion resistant reference pin (1
) has a head (2) and an intermediate part (3) made of a non-conductive material.
) and a base (4) are connected in series, and the head (2) extends in the direction toward the base (4) with a protrusion (2a) on which a threaded portion (2b) is formed. An adhesive layer (2C) is formed on the surface of the threaded part (2b), and the intermediate part (3) has a through hole (3) penetrated by the protruding part (2a).
a), and the base (4) has a threaded portion (2) of the protrusion (2a).
b), and has a screw hole (4a) to be screwed into the base (4a).
) into which a part of the intermediate portion (3) is tightly fitted.
) is formed.

There is no particular limitation on the material of the head (2) and base (4), and commonly used chromium-molybdenum steel, carbon steel for machine structures, alloy tool steel, etc. can be used, but wear-resistant An alloy tool steel such as SMDII is preferable because of its excellent properties.

There is no particular limitation as to the non-conductive material used for the intermediate part (3), and commonly used 5i3Na, N203
, ZrO2 or the like can be used.

The threaded length of the threaded portion (2b) and the threaded hole (4a), that is, the threaded depth, needs to be long enough to suppress the occurrence of loosening.

There is no particular limitation on the material of the adhesive layer formed on the surface of the threaded portion (2b), and epoxy adhesive or the like can be used.

As a result of manufacturing an electrolytic corrosion-resistant reference pin having such a configuration and using it in the welding process of automobile parts where electrolytic corrosion occurs, it was found that
Even after several months of use, no loosening or breakage was observed, and wear was significantly reduced compared to the conventional reference pins shown in Figures 2 and 3. It was confirmed that no damage to the pin was observed, and the amount of wear was O (less than the lower limit of measurement).

[Effects of the Invention] The present invention provides an electrolytic corrosion-resistant reference pin in which loosening of component parts and occurrence of abrasion and chipping caused by this are prevented, thereby stably preventing the occurrence of electrolytic corrosion. Therefore, the durability of the reference pin is 280 times more than that of steel, and the need to replace the reference pin is achieved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of the electrical corrosion-resistant reference pin of the present invention,
FIGS. 2 and 3 are explanatory diagrams showing different examples of conventional electrical corrosion-resistant reference pins, respectively. (Main symbols in the drawing) (1), Electrolytic corrosion reference pin (2): Head (2a): Projecting part (2b): Threaded part (2c): Adhesive layer (3): Middle part (3a): Through hole (4): Base (4a): Screw hole (4b): Concave part E] times Electrolytic corrosion resistant reference pin leaf 2811 Do-f---111- 13a I4b 148 2a 2B8. ,,: 24b 4C 4a

Claims (1)

[Claims] 1 A reference pin used for positioning a workpiece, in which a head, an intermediate part made of a conductive material, and a base are connected in series, and the head protrudes in the direction toward the base and is screwed. an adhesive layer is formed on the surface of the threaded part, the intermediate part has a through hole penetrated by the protrusion, and the base part has a threaded part of the protrusion. An electrolytic corrosion-resistant reference pin having a screw hole to be screwed into the pin, and further having a recess formed in the base portion into which a portion of the intermediate portion is tightly fitted.