JP2000204672A - Splice plate for high-tensile bolt frictional joint of material with different strength - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a splice plate which stably provides a high slip factor, for use in making a high-tensile bolt frictional joint with a member of different strength. SOLUTION: An integral splice plate 2 is formed by welding together steel members which differ in surface hardness, in such a manner that the ratio of the higher surface hardness of the frictional mating surface of the splice plate 2 to the smaller surface hardness of a steel member of different strength which is to be joined to the splice plate is 1.2 or more. The frictional mating surface with the higher surface hardness has concentric projecting and recessed portions formed by rolling in a region around a bolt hole therein, with the radius of the region being preferably twice the radius of the bolt hole, and with the projecting and recessed portions on a radial cross section taking the form of continuous or discontinuous mountains. The surface projecting and recessed portions are produced by rolling, with the angle of each projecting part being 50 to 120 degrees and the radius of curvature of the end of each projecting part 1 being 0.1 mm or less, and with the height from the surface of the steel plate prior to rolling to the end of each projecting part 1 being 0.2 to 1.0 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a splice plate for high-strength bolt friction joining used for friction joining of steel structures in buildings, bridges, and the like, and particularly to a splice plate for joining different-strength materials. It is about. The splice plate of the present invention is inexpensive and can stably obtain a frictional joint surface with a high slip coefficient,
By using this, the joining efficiency is improved, the number of bolts can be reduced, and the safety of the steel structure can be increased.

[0002]

2. Description of the Related Art When joining steel materials in series in the fields of construction, bridges, etc., so-called high-strength bolts are joined by joining steel materials to be joined, attaching steel contact plates on both sides thereof, and tightening with bolts. Friction welding is commonly employed. And the steel material used as an attachment plate is called a splice plate.

According to the design and construction guidelines of the Architectural Institute of Japan in friction welding of high-strength bolts, the friction surface, which is important for the joining strength, is a good red rust surface with black scale removed and a slip coefficient of 0.1.
It is stated that it is necessary to perform a treatment exceeding 45 and to check the slip coefficient by a slip proof test. In the field of bridges, there is a statement in the Road Bridge Specification and Commentary (Japan Road Association) that a slip coefficient of 0.4 or more should be obtained.

[0004] Usually, it is known that, in a good red rust state, the slip coefficient exceeds 0.45, and the slip resistance test is often omitted. However, a slip coefficient of about 0.6 may be obtained in the red rust state, but the rust generation state varies depending on environmental factors, steel material composition, and the like, and thus the dispersion is large.

[0005] It is clear that the higher the slip coefficient of the frictional joint surface is, the higher the joining strength is, the more preferable it is. In addition to the method of producing red rust on the steel material surface, as shown in JP-A-51-52628, In addition, there has been proposed a method of forming irregularities by shot blasting or the like prior to application, or a method of spraying a corrosion-resistant metal on a joint surface as shown in JP-A-1-206104. However, in the conventional method, not only can not form a sufficient roughness, there is a large variation in the shape of the unevenness, there is a limit to the slip coefficient obtained,
There was a problem that a slip coefficient exceeding a certain value could not be obtained.

On the other hand, as disclosed in Japanese Patent Application Laid-Open No. Hei 8-209809, the surface hardness ratio between the steel material to be joined and the splice plate is specified, and the surface layer is subjected to projection processing to significantly reduce the slip coefficient. An improved bonding structure is disclosed. However, the splice plate is usually a single steel material, and as long as it is used, for example, in the case of joining different-strength materials not less than in a girder flange in the bridge field, the surface hardness ratio with the splice plate is different. Therefore, there has been a problem that the joint strength is limited to a member having a lower slip coefficient.

[0007] In connection with the surface roughness (irregularity),
In JP-A-6-57828, 3 to 10 mm is applied over a range in which the fastening force of the bolt hole exerts an influence on the frictional joint surface.
Preferably, a convex part having a height of about 5 to 6 mm is integrally formed,
There is disclosed a splice plate in which blade-like protrusions having a height of about 1 to 3 mm are formed on the protrusions. However, 3-1
It is extremely difficult to integrally mold a projection having a height of 0 mm (preferably around 5 to 6 mm). Even when such a projection and a blade-like projection are formed on a scale,
When the surface hardness of the steel material to be joined (base material) is harder than that of the splice plate side, there is a problem that the protrusion cannot sufficiently penetrate and does not become a resistance to slip.

On the other hand, as shown in Japanese Patent Application Laid-Open No. 9-165826 filed earlier, the present inventors compacted a knurled piece around the bolt hole concentrically around the bolt hole. By rolling, a concavo-convex pattern was imparted, and a splice plate in which the hardness of the convex portions was harder than that of the steel plate to be joined was devised, thereby achieving an epoch-making improvement in the slip coefficient. However, as shown in FIG.
It is a rotating radial or twill shape, and in the rolling of the pattern using a rotary processing machine, if it does not always follow the same trajectory,
In some cases, the once formed uneven shape was crushed. Also, in order to obtain resistance to sliding by making the convex portion bite into the steel plate to be joined, it has been pointed out in the above-mentioned publication that the tip of the convex portion is preferably sharp. In order to sharpen the tip of the convex part in), the rolling pieces need to exactly follow the same trajectory during the rolling process, and it is necessary to remarkably increase the processing accuracy of the rolling pieces and the processing jigs. The time required for processing also required a considerably long time, and there was a problem in terms of productivity.

[0009]

SUMMARY OF THE INVENTION According to the present invention, when frictionally joining different-strength materials with high-strength bolts, a splice plate having a different surface hardness of the friction-joining surface is welded in accordance with the friction-joining, thereby improving the hardness of the friction-joining surface. It is an object of the present invention to provide a splice plate that exhibits a stable and high slip coefficient by always maintaining a certain ratio or more and forming reasonable unevenness at low cost.

[0010]

According to the present invention, the ratio of the surface hardness of the frictionally joined surface of the splice plate to the surface hardness of the steel material to be joined is set to at least 1.2, The inventors have found that the above problems can be solved by providing surface irregularities around the holes, and have made the present invention.

That is, the gist of the present invention is as follows.

(1) In a splice plate used as an attachment plate when frictionally joining different-strength materials with high-strength bolts, the surface hardness of the friction-joined surface and the surface hardness of the steel material to be joined are not a single steel material. Steel materials having different surface hardnesses are welded so that the ratio of the larger and smaller ones becomes 1.2 or more, and of the splice plates or the steel materials to be joined, the surface hardness of the friction joining surface is reduced. A high-strength bolt of different strength material characterized by forming concavities and convexities in the cross section in the radial direction concentric with the bolt hole around the bolt hole on the surface of the frictional joint surface on the larger side. Splice plate for friction welding.

(2) The splice plate for high-strength bolt friction joining of a different-strength material according to (1), wherein the irregularities are formed by rolling.

(3) The angle of the projection of the unevenness is 50 to 1
Any one of (1) to (2), wherein the angle is 20 degrees and the radius of curvature at the tip of the convex portion is 0.2 mm or less.
A splice plate for high-strength bolt friction joining of a material having different strength according to the above item.

(4) The height of the projections of the irregularities is increased at a constant rate or stepwise toward the outer side in the radial direction, and the innermost and outermost parts with respect to the difference between the innermost and outermost radii of the uneven area. (1) to (1), wherein the ratio of the height of the convex portion from the surface of each steel plate is 0.10 or less.
The splice plate for high-strength bolt friction joining of a different-strength material according to any one of (3).

(5) The radius of curvature of the concave portion of the concave and convex is 0.
(1) to (4), which are not less than 2 mm.
The splice plate for high-strength bolt friction joining of a different strength material according to any one of the above.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Conventionally, in order to increase the slip coefficient of a steel material, a method of increasing the surface roughness of a frictional joint surface by shot or grid blast has been generally adopted. However, in blasting or the like, the surface roughness, that is, the difference in height of the surface irregularities depends on the type of steel and shot grains, but is at most about 150 μm, and the increase in the slip coefficient due to this is naturally limited. However, according to the study of the present inventors, in order to increase the slip coefficient with the same surface roughness, it is necessary to increase the hardness (surface hardness) of the friction joining surface on the side with the larger surface roughness. It has been found. This is presumably because the hard and rough surface irregularities bite into the relatively soft and low-friction friction surface. Even if rough irregularities are provided on the side where the surface hardness is small, the irregularities are crushed and the bite is insufficient. Also, when the surface roughness on the side with the higher surface hardness is smaller than the surface roughness on the side with the lower surface hardness, the bite is insufficient and a high slip coefficient cannot be stably obtained.

For this reason, in the present invention, first, the ratio of the surface hardness of the frictional joint surface of the splice plate to the surface hardness of the steel material to be joined is set to 1.2 or more. Needless to say, the higher the surface hardness ratio is, the more preferable it is. On the other hand, some surface layer hardening treatment, for example, quenching or induction hardening is particularly effective for quenching only the surface layer. However, in the field of bridges, splice plates are very large, and if the above-mentioned hardening treatment is performed before cutting or bolt hole drilling, subsequent cutting and bolt hole drilling become difficult, and hardening treatment after cutting and bolt hole drilling is also performed. However, in practice, it is extremely difficult to implement in practice, such as when distortion occurs, and particularly when induction hardening is performed, a large-scale equipment is required.
On the other hand, the number of bolts connected per joint in the bridge field is several hundred, and if the slip coefficient can be stably improved even if the slip coefficient is 10 to 20%, the number of bolts connected can be reduced accordingly. In consideration of such a case, the hardness ratio is set to 1.2 or more. The term “surface hardness” as used herein particularly refers to the side on which the surface hardness is large also provides rough irregularities as described later, and means the hardness of the convex portion from the viewpoint of biting.

Next, the surface roughness of the splice plate and the steel material to be welded must be larger (coarse) on the side having the higher surface hardness of the friction welding surface than the other, for the reasons described above. Needless to say, the larger the surface roughness of the side with the larger surface hardness (the coarser the surface), the more preferable it is. Should be 0.2mm
The above is preferred.

It is not necessary that the surface hardness ratio or the surface roughness be a problem on the entire surface of the frictional joint, and at least the bolt hole is taken into consideration in consideration of the region where the fastening force (contact pressure) of the bolt is exerted. May be any area up to twice the radius of the bolt hole.

From such a viewpoint, the surface irregularities are provided concentrically around the bolt holes. This is extremely rational in consideration of the fact that the fastening force of the bolt extends concentrically around the bolt hole. In addition, the concentric shape has no anisotropy with respect to slip and is effective not only when uniaxial tension is applied but also when bending and shear components are added to the steel material.

The concentric concavo-convex shape around the bolt hole is a continuous or intermittent chevron in a radial cross-section such that the protruding portion sufficiently bites into the steel material to be joined and has resistance to slip. When the cross section in the radial direction is mountain-shaped, it means that the uneven processing pattern viewed from the upper surface is ring-shaped, and the rolling piece can always follow the same locus. For this reason,
The rolling process, in particular, the formation of the projections becomes extremely easy, and the rolling time can be reduced. Further, it is easy to sharpen the angle of the convex portion and to reduce the radius of curvature at the tip of the convex portion, and it is possible to define the details of the uneven shape as a component in the present invention. In these respects,
Concentric radial cross section (ring shape when viewed from above)
Is the most preferred shape.

Here, since the above-mentioned unevenness of the frictional joint surface is not necessarily the entire surface processing, it is not exactly defined by the surface roughness, but the projection must be projected higher than the surface of the splice plate. As described above, in order to enjoy the effect more sufficiently than the conventional blast processing as described above, it is meaningful that the height of the convex section is higher than the convex section height 0.2 mm obtained by the blast processing or the like. is there. vice versa,
If it exceeds 1.0 mm, the margin for improving the slip coefficient is small, although the processing load increases in terms of the ease of processing the irregularities and the processing time. From the above, the height of the convex portion is 0.2 to
Desirably, it is 1.0 mm.

As described above, it is necessary to make the projections high and sharp and to make the hardness of the projections harder than the surface hardness of the steel material to be welded in order to bite into the steel material to be welded. However, it is not necessary to increase the hardness over the entire cross section of the splice plate, and from the viewpoint of biting into the steel material to be joined, at least の of the height of the projection from the tip of the projection.
It is good if it is hard.

The method of increasing the surface hardness is generally the easiest to quench, but as described later, if a process for forming irregularities is performed by a rolling method or the like, even a hard material can be easily formed. Since processing is possible, it is possible to process even a steel material after quenching. It is more costly to perform the quenching process in the state of a large steel material.
This is advantageous in terms of productivity.

Further, when the hard region extends over the entire cross section of the steel material, the wear of the drill increases when the bolt hole is drilled, which may adversely affect the drilling. Desirably, only the surface layer has the required hardness and the inner layer is relatively soft. Or,
It is desirable to harden by an induction hardening treatment capable of quenching only the surface layer after the unevenness processing. However, when drilling the bolt holes using a laser processing machine or the like, the present invention is not limited thereto, and the entire cross section may be hard.

In the case where the improvement in slip coefficient may be small, as in the case of a bridge, for example, it is not necessary to perform aggressive surface hardening treatment, and a higher strength steel (for example, HT490) than the steel plate to be joined is used. HT570, HT69
0, HT780, etc.).

As described above, in addition to the case where the high strength steel is used for the splice plate and the case where the strength is higher than the steel plate to be joined by performing the surface hardening treatment, as an additional effect, The board thickness is usually
It is possible to make the plate thickness, which is said to be half the thickness of the steel plate to be joined, thinner, and together with the reduction of the number of bolts due to the improvement of the slip coefficient, the weight of the splice plate can be significantly reduced. This makes it possible to significantly improve the workability at the site.

Next, a processing method for forming irregularities will be described.

The method of forming the irregularities is preferably a rolling method. In a method such as mechanical cutting, the convex part is the same or lower than the steel sheet surface before processing, so in order to make the convex part higher than the steel sheet surface, the entire friction welding must be processed, Costly and expensive. In this regard, according to the rolling method, since irregularities are formed by pressing,
Since the convex portion is raised and the convex portion is always higher than the surface of the steel sheet before processing, desired unevenness can be formed by partial processing. In addition, according to the rolling method, metal scraps and metal powder are not generated, and the load on a tool (in the case of rolling, a rolling piece) is not only small, but also it can be processed into a hard material. There are advantages. As described above, the ability to form a roll on a hard material also makes it possible to process a steel material having sufficient hardness before processing, which is extremely advantageous in terms of manufacturing cost.
This is not possible with mechanical cutting methods in terms of tool wear.

Further, it is desirable that the processing region in which irregularities are formed concentrically with the bolt hole around the bolt hole by rolling to cover a region having a radius at least twice the radius of the bolt hole from the center of the bolt hole. . A wider rolling area is better as it has no adverse effect on the slip coefficient, but it is better. However, the surface pressure due to bolt fastening is higher at the periphery of the bolt hole and sharply decreases outward, so the productivity of the rolling process is higher. From the standpoint of cost, cost, etc., it is sufficient if the radius is five times the radius of the bolt hole. However, in actuality, it is often fastened with multiple bolts, so if it interferes with the adjacent bolt holes and the rolling process around it, or if the splice plate protrudes, irregularities are naturally formed within the range Will be done.

It should be noted that the unevenness processing need not necessarily be performed on the entire surface of the region, but may be performed partially. The term “part” refers to an interrupted chevron shape, rather than a continuous chevron shape in the radial direction (referred to as full-surface processing). Since a small pressure is required, not only is processing efficiency advantageous, but also processing can be performed with a small-sized apparatus such as a portable type that can be processed on site. Of course, the slip coefficient is slightly inferior to that of the entire surface processing, but it does not matter at all depending on the application and the target slip coefficient. Therefore, the slip coefficient may be determined in consideration of the processing efficiency and the like according to the purpose.

FIG. 1 is a cut perspective view showing an example of a knurled rolled portion around a bolt hole in the splice plate of the present invention. FIG. 1A is an example in which a cross-sectional shape of a radial projection 1 around a bolt hole of a splice plate 2 has a continuous mountain-like uneven shape, and FIG.
Shows an example in which the cross-sectional shape of the radial convex portion 1 around the bolt hole forms an intermittent mountain-shaped uneven shape.

The angle of the convex portion is set to 50 so that the convex portion sufficiently penetrates the steel plate to be joined and has resistance to slip.
１２０120 degrees and the radius of curvature at the tip of the convex portion is 0.2 mm
It is desirable to make the following. The reason is that the convex angle is 1
When the angle is larger than 20 degrees, the bite into the steel plate to be joined is insufficient. On the other hand, when the angle of the convex portion is smaller than 50 degrees, not only the rolling becomes difficult but also the convex portion is easily broken. is there. It is clear that the sharper the tip of the projection is, the more preferable it is in terms of biting into the steel plate to be joined. Here, the basis for setting the radius of curvature of the tip of the convex portion to 0.2 mm or less is based on the results of the slip test of the present inventors.

It should be noted that the height of the unevenness is not necessarily the same over the entire processing region. FIG. 2A shows that the height of the convex portion 1 is increased at a constant rate or stepwise toward the outer peripheral portion. This takes into account the surface pressure distribution around the bolt hole due to bolt fastening. In FIG. 2B,
The difference between the outermost and innermost radii (R-
ratio (Hh) to the height difference (Hh) of the convex portion to r)
By setting / (R-r) to 0.10 or less, it is possible to secure sufficient penetration into the steel plate to be joined and improve the slip coefficient even on the outside where the surface pressure is low. (Hh) / (R
If -r) exceeds 0.10, the projections cannot contact the entire surface of the steel plate to be joined, and the effect of imparting irregularities cannot be enjoyed. Therefore, the upper limit was set to 0.10.

Although the concave portions of the concave and convex do not contribute to the improvement of the slip coefficient, it is desirable that the radius of curvature of the concave bottom is 0.2 mm or more from the viewpoint of the fatigue characteristics and fracture toughness of the splice plate. Since the concave processing by rolling receives compression,
Although somewhat advantageous against fatigue, a recess with a small radius of curvature is equivalent to having a sharp notch and may be problematic depending on usage conditions.

Furthermore, in the case of bolt joining of different strength materials which are particularly targeted by the present invention, there are cases where it is difficult to secure a surface hardness ratio particularly with a splice plate made of a single steel material. For this reason, steel materials capable of ensuring a sufficient surface hardness ratio corresponding to each of the steel materials to be joined having different strengths are welded and joined to form a single splice plate. Since the joining strength is restricted to the smaller surface hardness ratio through the slip coefficient, the side with the larger surface hardness ratio has the advantage of 10%.
0% cannot be enjoyed. Conversely, in order to secure a predetermined surface hardness ratio at the friction-joined surfaces of the steel plates to be joined having different strengths, an excessive hardening treatment must be performed over the entire surface of the splice plate in some cases.

On the other hand, the splice plate according to the present invention is formed by welding a steel material having an appropriate surface hardness ratio to each of the different strength materials to be joined. Problems can be avoided.

[0039]

EXAMPLES In order to exemplify the usefulness of the present invention, surface irregularities and protrusion hardness of a splice plate were imparted according to the present invention, and the slip coefficient was measured using a test piece as shown in FIG. As shown in FIG. 3, the steel to be joined is SM490.
A different material of A steel 4 and SM570Q steel 5 was used, and F10T high strength bolt 6 was used as a bolt. The splice plate 3 in which steel materials having different surface hardnesses are welded by the welding wire 7 is according to the present invention.

Table 1 shows examples of the present invention, and Table 2 shows comparative examples. In the case of the knurl rolled material, the surface hardness is 0.1 mm below the top of the convex portion of three peaks in the thickness (depth) direction in a cross section cut out from a preliminary test piece manufactured in the same lot. Average value of hardness measured at three points at 1 mm pitch. In the case of shot blast material, three points at 0.1 mm pitch in the thickness direction from 0.1 mm below the surface of frictional joint surface at three cross sections of the same lot material It is the average value of the measured hardness. Since Examples 1 to 4 all have an appropriate frictional joint surface unevenness and hardness ratio based on the present invention,
The above high slip coefficient is exhibited.

On the other hand, in Comparative Examples 5 to 8, since one or more of the constituent elements of the present invention are out of the range of the present invention, the slip coefficient is generally low. That is,
In Comparative Example 5, since the splice plate was a single steel plate (in this comparative example, the same steel plate as the steel plate to be joined (1)), the hardness ratio was insufficient for the steel plate to be joined (1). Is low. Comparative Example 6 has a low slip coefficient because the surface unevenness is shot blasting instead of knurling and the surface roughness of the frictionally bonded surface on the relatively hard side is smaller than the other. Further, in Comparative Example 7, since the unevenness processing is mechanical cutting,
The slip coefficient is low because the convex portion is lower than the steel plate surface (the convex portion tip does not protrude from the steel plate surface). Comparative Example 8
Since the radius of curvature at the tip of the convex portion formed by knurling is large, bite into the steel material to be joined is insufficient, and the slip coefficient is low.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

According to the present invention, a stable and high slip coefficient can be easily obtained. As a result, it can be provided as a structural member for improving the reliability of a high-strength bolt friction joint in the field of construction, bridges, and the like, and its industrial value is high.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cutaway perspective view showing one embodiment of a knurled rolled portion of the present invention, in particular, FIG. 1 (a) is a chevron having a continuous radial cross-sectional shape, and FIG. It is the figure which showed the case where the Yamagata eggplant did.

FIG. 2 is a view showing a splice plate of the invention according to claim 4 of the present invention, wherein (a) is a cutaway perspective view and (b) is a cross-sectional view of (a).

FIG. 3 is a view showing a shape of a test body used for measuring a friction coefficient.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Convex part 2 Splice plate 3 Bolt hole center line 4 Steel material to be joined (SM490A steel in this example) 5 Steel materials to be joined having different strengths (SM5 in this example)
6 high strength bolt 7 welding line r innermost radius R outermost radius h innermost convex height H outermost convex height

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuyoshi Uno 20-1 Shintomi, Futtsu City Within the Technology Development Division of Nippon Steel Corporation (72) Inventor Atsuhiko Yoshie 1 Kimitsu, Kimitsu City Nippon Steel Corporation F term in Tsu Works (reference) 2E125 AA01 AB12 AC15 AG03 AG12 BB01 BB09 BB22 BB33 BC01 BD01 BD07 BE05 BF01 CA05 CA06 CA14 CA72 CA94 DA01 DA03

Claims (5)

[Claims] 1. A splice plate used as an attachment plate when frictionally joining different-strength materials to high-strength bolts,
Instead of a single steel material, weld steel materials with different surface hardness so that the ratio of the surface hardness of the friction-joined surface to the large and small surface hardness of the joined steel material is 1.2 or more. And, of the splice plate or the steel material to be joined, around the bolt hole on the surface of the frictional joint surface on the side with the greater surface hardness of the frictional joint surface, concentrically with the bolt hole, and its radial cross-sectional shape A splice plate for high-strength bolt friction joining of different-strength materials, wherein the splice plate forms a continuous or interrupted mountain-shaped unevenness. 2. The splice plate according to claim 1, wherein the irregularities are formed by rolling. 3. The method according to claim 1, wherein the angle of the convex portion of the unevenness is 50 to 120 degrees, and the radius of curvature of the convex portion tip is 0.2 mm or less. Splice plate for high strength bolt friction joining of different strength materials. 4. A method according to claim 1, wherein the height of the projections is higher or lower at a constant rate toward the outer side in the radial direction, and the innermost and outermost parts are respectively different from the innermost and outermost radii of the uneven area. The ratio of the height of the projections from the surface of the steel sheet is 0.10
4. The method according to claim 1, wherein:
A splice plate for high-strength bolt friction joining of different-strength materials according to the above item. 5. A curvature radius of a concave portion of the unevenness is 0.2 mm.
The method according to any one of claims 1 to 4, wherein
A splice plate for high-strength bolt friction joining of a material having different strength according to the above item.