JPS5824644Y2 - Positioning fastening bolt with fall prevention - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a bolt for positioning and fastening with a drop-off prevention function.

Generally, when connecting two fastened parts with a bolt and nut in a narrow space, the bolt is secured to one of the fastened parts in some way, such as by clipping it, so that the bolt does not fall off during work. Usually, the bolt insertion hole of the member to be fastened is made a blank hole, and the nut is tightened from one side.

The fixing methods commonly used to prevent this from falling off are:
A method is used in which the bolt shaft is press-fitted into the bolt insertion hole of one of the fastened members and then peeled off.

However, like the bearing cap attachment part on the crankshaft side of the connecting rod used in engines,
In cases where the bolt itself also has the effect of positioning the connecting rod base and bearing cap, the bolt insertion holes of the connecting rod base and bearing cap, which are fastened members, must both have eutectic precision. A fitting insertion hole is required.

Therefore, in the past, the bolt insertion holes in the connecting rod base and bearing cap were precision-machined to form a mating insertion hole, and the shaft of the bolt was precision-machined to become a mating shaft, and the lower part of the mating shaft neck was A chevron-shaped serration is provided on the shaft, and fixing and positioning are performed simultaneously by press-fitting and fitting the serration portion and the fitting shaft portion into the fitting insertion hole.

However, the accuracy of the outer diameter of the serrations is limited to approximately 9.1 mm, and during the preliminary pressure work with a constant press-fitting force, the bolt head bearing surface does not come into complete contact with the connecting rod base bearing surface, and then Even if the nut is tightened to a constant torque during assembly work, the bolt seating surface may not be completely attached to the connecting rod base seating surface, creating a gap. had.

For this reason, it is extremely difficult to carry out pre-compression work using a constant press-in force, which increases costs due to adjustment of the press-in force and confirmation inspection after press-fitting, and causes problems such as nuts loosening and falling off during use.

The present invention solves these drawbacks, namely, the shaft part following the bolt head is precisely machined to form a high-precision fitting shaft, and the bolt is attached to the outer periphery of the lower neck of the fitting shaft part. Provide a relief groove in contact with the head seat.

A plurality of protrusions that are in contact with this relief groove and have a certain width in the axial and circumferential directions, and whose top portion is slightly larger than the fitting shaft diameter and whose bottom portion is equal to the fitting shaft diameter, are arranged on the same circumference. By providing them at intervals, the bolt can be reliably fixed in the fitting hole of the fastened member by press-fitting with a constant pressure, with the bolt head seat always in complete contact with the fitting hole seating surface. , the positioning of the two fastened members during assembly is accurate, and the bolt can be obtained by rolling.

Hereinafter, the present invention will be explained in detail based on an embodiment of a connecting rod bolt shown in the drawings.

Fig. 1 is a front view of a connecting rod bolt according to the present invention, and Fig. 2 is a side view thereof. An escape groove 2 is provided.

In contact with this relief groove 2, a plurality of protrusions 3 whose top portions 3' are slightly larger than the shaft diameter of the fitting shaft 5 and have widths in the axial and circumferential directions are installed on the same outer periphery of the fitting shaft 5. They are provided at equal intervals on the circumference.

The top 3' of this protrusion 3 is a cross section perpendicular to the axis, that is, in FIG.
As shown in FIG. 3(a), an enlarged side view of the
It forms a concentric arc.

Furthermore, a fitting shaft 5 on the opposite side of the relief groove 2 is in contact with the protrusion 3.
, there are provided recesses 4 whose bottom portions 4' are slightly smaller than the shaft diameter of the fitting shafts 5, and whose axial and circumferential widths are approximately equal to those of the projections 3, equal to the number of projections 3.

The bottom 4' of this recess 4 is a section perpendicular to the axis, that is, in FIG.
As shown in FIG. 3(b), an enlarged side view of the
It forms a concentric arc.

Further, following this recess 4, there is a fitting part 5' of the fitting shaft 5, and at the tip of the fitting part 5' there is a screw 6 provided with a screw 6 having an outer diameter smaller than the outer diameter of the fitting part 5'. There is pestle 7.

With the configuration as described above, by forging the recess 4 on the fitting shaft 5, the excess wall of the recess 4 can be easily forged as the protrusion 3.

In addition, since the diameter of the portion between the adjacent protrusions 3 and 3 and between the recesses 4 and 4 is the diameter of the fitting shaft equal to the outer diameter of the fitting portion 5', it is easy to form the fitting shaft 5 by rolling. It is easy to manufacture the rolling piece to be used, and the protrusion 3 and the recess 4 are formed by uneven rolling, and the under-neck groove 2 and the fitting part 5' are finished, that is, the entire fitting shaft 5 is made of a contracted rolling piece. , can be simultaneously formed by a method of simultaneous cold rolling after heat treatment.

Therefore, it is possible to obtain a connecting rod bolt with high dimensional accuracy of 0.04 mm or less at the protrusion 3 and 0.02 mm or less at the fitting portion 5'.

Furthermore, if a connecting rod bolt constructed and formed in this manner is used to assemble a connecting rod as shown in FIG. Connecting to hole 11
The fitting part 5' of the rod bolt is fitted and inserted, and the protrusion 3 is inserted into the connecting rod base 9 of the fitting insertion hole 11.
is press-fitted into a position close to the fitting insertion hole seating surface 12 of the connecting rod bolt seating surface 8 and the fitting insertion hole seating surface 1.
It is in close contact with 2.

At this time, a portion of the top 3' of the protrusion 3 is pushed into the relief groove 2 in contact with the protrusion 3, so that the tightening torque can be reduced.

Thereafter, the fitting insertion hole 13 of the connecting rod bearing cap 10 is inserted into the fitting portion of the connecting rod bolt that protrudes from the connecting rod base 9.

Furthermore, by screwing the hexagonal nut 14 into the screw 6 of the threaded rod 7 of the connecting rod bolt protruding from the connecting rod bearing cap 10 and tightening it, the connecting rod base 9 and the connecting rod bearing cap 10 are accurately connected. Can be assembled.

As detailed above, the connecting rod bolt according to the present invention has a high precision, that is, a protrusion accuracy of 0.04 rru'n.
Connecting with a mating accuracy of 0.02mm or less
This is a rod bolt.

There is no need for finish grinding of the mating shaft or finish machining of the relief groove under the neck.

Improved efficiency of preliminary press-fitting work and eliminates the need for confirmation inspection after press-fitting.

Due to the cold heading process after heat treatment, a hardened surface layer is formed on the entire fitting shaft such as relief grooves, protrusions, fitting parts, etc., improving fatigue strength.

Positioning, fixing, and tightening are reliable, and there are no problems such as loosening of nuts or falling off of bolts during use.

The effect is very strong. In the examples, we have explained bolts for connecting rods, but the bolt shaft itself is a high-precision fitting shaft with a positioning effect, and can be used for all fastening applications that require prevention of falling off. Of course, it can be used for bolts.

[Brief explanation of drawings]

Fig. 1 is a front view of a connecting rod bolt according to the present invention, Fig. 2 is a side view, and Fig. 3(a) is an X of Fig. 1.
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FIG. 3 is an assembled view of the connecting rod showing the rod bolt in use. 1...Bolt head, 2...Escape groove, 3...Protrusion, 3'...
... (protrusion) top, 4 ... recess 4 ... (recess) a
In 5...Mating shaft, 5'...Mating part, D...Protrusion 3
and the protrusion 3 and the part between the recesses 4, 6...screw, 7...screw rod, 8...seat surface, 9...connecting rod base, 10...connecting rod Rod bearing cap, 11... Fitting insertion hole, 12... Fitting insertion hole seating surface, 13... Fitting insertion hole, 14... Hexagonal nut.

Claims (1)

[Scope of utility model registration request] A relief groove is provided on the outer periphery of the lower part of the neck of the fitting shaft portion following the bolt head, in contact with the bolt head seating surface, and has a certain width in the axial direction and circumferential direction in contact with the relief groove, and the top thereof is A plurality of protrusions that are slightly larger than the fitting shaft diameter and whose bottom portions are equal to the fitting shaft diameter are provided at equal intervals on the same circumference, and further adjacent to the protrusions and whose bottom portions are slightly smaller than the fitting shaft diameter; A bolt for positioning and fastening to prevent falling off, characterized in that the bolt is provided with a recess whose axial and circumferential widths are approximately equal to those of the protrusion.