JPH065121Y2 - Finger joint for vertical connection of skeleton structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a means for improving the joint performance of a finger joint used in a longitudinal joint for structural timber.

[Conventional technology]

Conventionally, finger joints have been generally adopted as a longitudinal joint method for the structure of wood together with scarf joints due to their excellent workability, and the method is, for example, inward from the opposite end faces of plywood to the opposite plate face direction of plywood. Such that the finger portions are provided by making parallel cuts obliquely intersecting, and the finger portions that mesh with each other are joined together by an adhesive (see Japanese Utility Model Publication No. 58-45051).
Alternatively, a finger joint in which the abutting surface of the wood is in the plate thickness direction and is engraved in parallel in the width direction (JP-A-57-66)
901) and the like are known.

[Problems to be solved by the invention]

Among those described in the prior art, in the former case, when the material is plywood because the cutter enters diagonally, the tip of the finger part is not chipped and wrinkles do not occur, but the tilt direction of the finger is plywood. Since it is engraved in parallel with the facing plate surface, the fingers at both end positions reach the side faces of the plywood in particular, the outer ends of the fingers arrive, and the fingers become short, so there is a limit to the increase in the bonding area, and Since the joint portion is short, stress concentration is likely to occur and there is a limit to improvement in strength. Also, in the latter, since the length of the fingers is limited by the plate thickness, the latter also has a limit in the adhesive area and the joint portion and stress concentration is likely to occur. However, due to its short length, it had a problem of poorer joining performance than the scarf joint.

The present invention has been made in view of the above problems of the conventional technique, and an object of the present invention is to sufficiently increase the bonding area and the bonding length, and therefore to reduce stress concentration. An object of the present invention is to provide a finger joint for structural longitudinal connection of wood, in which generation is suppressed and a specific strength with the material strength can be expected to be as high as 94% to 96%.

[Means for solving problems]

The present invention will be described with reference to the drawings. The side surfaces of the finger joint portions 1 engraved in parallel are inclined from each other in the direction perpendicular to the butt facing end face of the wood from the front surface to the back surface side of the wood. The scarf shape is used, and the length of the bonded portion in the butting direction is increased.

〔Example〕

The inclination ratio of the finger joint part 1 in the present invention is 1.
It was desirable to form it in a scarf shape of 0, and good results could be obtained. With respect to the bending performance of the timbers joined according to the present invention, the results of the tests carried out at the Hyogo Prefectural Industrial Experiment Station will be described in detail below. The degree to which the finger joint 1 is tilted in a scarf shape as shown in FIG. Ratio of thickness to plate thickness The test results for samples with gradually increasing slope values of 0.5, 1.0, and 1.5 are shown in Table 1 below, and various types of adhesives such as resorcinol-phenol, epoxy, and urethane were used. In any case, the specific strength at the inclination ratio of 1.0 (inclination angle of 45 °) is 94 to 96% of the material strength, which is a large value, and the value of the conventional finger joint (inclination ratio of 0). It is much larger than 74-90%.

Since the specific strength reached the maximum value at the inclination ratio of 1.0, it was not necessary to make the inclination ratio higher than that and the yield was good.

Further, it was found from the test results that, when the inclination ratio is 1.0, there is little variation in the specific strength among the adhesives, so that stable bonding performance can be obtained regardless of the type of the adhesive.

Further, the relationship between the slope ratio and the specific strength based on the above-mentioned various tests is illustrated as follows.

Relationship between effective ratio of specific strength and slope ratio [Advantages of the Invention] Since the present invention is configured as described above, since each finger is provided in the abutting direction at a right angle to the abutting facing end surface of the wood, each finger must be surely formed to be long. Since the stress is dispersed over the long joint portion, the stress concentration generated at the joint portion is relaxed, the adhesive area is increased, the side surface of the finger joint portion 1 itself is loosened, and ideal adhesive joint is possible. There is little variation in specific strength between adhesives, stable bonding performance can be obtained regardless of the type of adhesive, and even adhesives suitable for factories where the adhesive conditions such as temperature are well controlled, and difficult to manage sites Adhesives applied to etc. can be applied to both of them universally, and workability is excellent, and it is possible to make vertical joints for structures with high strength reliability. It can also be used for joining (longitudinal connection) the outermost layer of the laminated lumber of large cross-section lumber that requires a large amount of force.

[Brief description of drawings]

FIG. 1 is a plan view of the present invention, FIG. 2 is a side view, and FIG. 3 is an enlarged view of the joint portion of FIG. 1 ... Finger joint

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shozo Shimizu 108 Kasawa, Yamazaki-cho, Shishiwa-gun, Hyogo Prefecture 2 (56) Reference JP-A-57-66901 (JP, A) U) Actual public Sho 58-45051 (JP, Y2)

Claims (1)

[Scope of utility model registration request] 1. A finger joint part 1 formed by obliquely arranging the side surfaces of fingers engraved in parallel from the front surface of the wood toward the rear surface side in a direction perpendicular to the butt-opposing end surface of the wood and the direction perpendicular to the butt-opposing end surface of the wood. The scarf-shaped finger joint for vertical connection.