JPH0976082A - Method and equipment for welding cross bar steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely join crossing reinforcing bar by bringing the lower face of one reinforcing bar into press-contact with the upper face of the other reinforcing bar, applying vibration near the contact part so as to rub the contact face and thereby pressure-welding the joining faces through the frictional heat and the pressing force. SOLUTION: A signal is transmitted to a servo amplifier in accordance with a prescribed oscillation frequency and amplitude, thereby vibrating a hydraulic cylinder 72 for vibration in accordance with the prescribed oscillation frequency and amplitude, and also vibrating linearly in the horizontal direction a horizontal reinforcing bar 2 held by a clamping means 71. Then, a hydraulic cylinder for upsetting is actuated by its controller, bringing a vertical reinforcing bar 1 into contact with the horizontal reinforcing bar 2 and pressurizing it by a prescribed welding pressure. As a result, frictional heat is generated on the joining face at the intersection 3, with the vertical reinforcing bar 1 pressure- welded to the horizontal reinforcing bar 2. Upon the elapse of a set vibration time, a signal is made zero from the signal generating part to the servo amplifier, stopping the operation of the hydraulic cylinder 72 for vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for joining crossed steel bars for joining intersecting points of intersecting deformed reinforcing bars when, for example, a reinforcing bar lattice of a reinforcing bar concrete structure is manufactured.

[0002]

2. Description of the Related Art In recent years, with the increase in the size of reinforced concrete structures, the structural strength of reinforced concrete has been increased by using a reinforcing bar grid in which deformed steel bars of high strength and large diameter are joined in a grid pattern. . When manufacturing this rebar grid,
There is a great demand for cross-joining methods and joining devices that are safe, labor-saving, and have excellent working environments.

[0003] Conventionally, as a method of joining a cross joint of crossed steel bars such as a reinforcing bar grid, from a simple method of fixing the intersection with a wire, an arc welding method, an upset butt welding method, a flash butt welding method or the like at the intersection point. The resistance welding method is used for welding. As the arc welding method,
Covered arc, gas shield arc welding, etc. are applied, which is a method of welding while filling a crossing intersection with molten metal. In recent years, a gas shield arc welding device is mounted on a robot arm for automatic welding. The upset butt welding method is a method in which electric current is applied to a joint portion of cross-shaped deformed steel bars under pressure to generate jule heat at the joint portion, and when the temperature reaches a temperature at which joining is possible, pressure is applied and melt-bonding is performed. In the flash butt welding method, an electric current is applied to a pair of cross-shaped steel bars to be joined, and a short circuit and a discharge are alternately repeated at the joining point to heat the joining point and pressure is applied when the joining temperature is reached. Is a method of joining.

Further, when the joint surfaces of the two objects to be welded are rotated relative to each other under pressure, the relative rotational speed is set to zero when the joint parts reach an appropriate high temperature due to frictional heat generation. A method of joining rebars by a rotary friction welding method in which the applied pressure is increased by pressure welding is also disclosed in, for example, Japanese Utility Model Laid-Open No. 4-50447 and Japanese Utility Model Laid-Open No. 61-136011.

In the method disclosed in Japanese Utility Model Laid-Open No. 4-50447, a reinforcing rod and a male screw rod are welded to both sides of a square steel plate by rotary friction welding to form a pile head joint metal. 61-13
In the method disclosed in Japanese Patent No. 6011, a male screw machined to a required size in advance is crimped to a rebar end to be joined by a rotary friction welding method, and the male screw is a coupler having a female screw.
It is screwed to and the deformed bar is joined.

[0006]

However, in the method of fixing the intersections of the cross-shaped deformed steel bars with wires, almost no joint strength can be expected and the seismic performance is poor.

The method of joining the intersections of cross-shaped deformed steel bars by arc welding has poor joining efficiency, and for example, the time required to form one cross joint is about 500 seconds. Further, in the gas shield arc welding using a welding robot, the welding time for forming one cross joint is about 180 seconds or more, and the welding efficiency for forming many cross joints is poor. .

[0008] When joining an intersection of deformed steel bars by the upset butt welding method, a large amount of electric power is required to heat the intersection, so that the diameter of the reinforcing bar is restricted to a relatively narrow range. When joining intersections of deformed steel bars by flash butt welding, it is possible to join large-diameter reinforcing bars because it can be joined with less electric power than in the case of the upset butt welding method, but it is possible to join when there are many joined parts. It cannot be applied to the joining of cross joints such as a grid-shaped rebar lattice having a large number of intersections, because the current flowing through the parts is shunted at each joined portion, and the current required for flashing cannot be obtained.

In addition, Japanese Utility Model Laid-Open No. 4-50447 and Japanese Utility Model Publication Sho 61.
The method of joining rebars by rotational friction disclosed in Japanese Patent Publication No. -136011 is applicable to butt joints because the entire rebars to be joined are mechanically rotated around the axis, but joints of deformed steel bars are joined. Not applicable in case.

The present invention has been made in order to solve the above disadvantages, and a method for joining crossed steel bars, which can form a cross joint of steel bars reliably in a short time and can obtain a joint having good performance, and The purpose is to obtain a joining device.

[0011]

A method for joining crossed steel bars according to the present invention is a method for joining crossed steel bars, which joins steel bars or round bars having the same diameter or different diameters to a cross joint,
The lower surface of one steel bar or round bar is brought into pressure contact with the upper surface of the other steel bar or round bar, and vibration is applied to the vicinity of the contact portion of the upper and lower steel bars or round bars, and the contact surface of the upper and lower steel bars or round bar due to the vibration. Are rubbed, and the joining surfaces of the upper and lower steel bars or round bars are pressed by the generated friction heat and pressure.

Joining pressure P for bringing the above-mentioned joining end faces into pressure contact
In the range of 25 N / mm ² to 75 N / mm ² , and the vibration amplitude A =
0.5 mm to 5 mm, frequency f = 50 Hz to 250 Hz,
Range where the product P · A · f of the welding pressure P, the amplitude A and the frequency f exceeds a curve showing a constant value, with the amplitude A = 0.5 mm and the frequency f = 50 Hz when the welding pressure P is 75 N / mm ^2. When the joining pressure P is 25 N / mm ² , the amplitude A = 5 mm and the frequency f = 215 Hz are used as the reference, and the product P · A · f of the joining pressure P, the amplitude A and the frequency f exceeds the curve showing a constant value. It is desirable to set it in a range that does not exist. At this time, it is advisable to set the vibration time of the end portion within the range of 5 seconds to 60 seconds.

The cross bar joining apparatus according to the present invention has a holder, a pressurizing means, and a vibration generating means, and joins cross bars that have the same diameter or different diameters or round bars to a cross joint. In the joining device, the holder holds the pressurizing means and the vibration generating means, and is positioned at the cross joint part of the steel bar or round bar, and the pressurizing means is fixed to the lower part of the upper frame of the holder by the hydraulic pressure for upsetting. It has a cylinder, and presses one steel bar or round bar from the surface opposite to the joining surface to bring it into pressure contact with the joining surface of the other steel bar or round bar, and the vibration generating means crosses either one. It is characterized in that vibration is applied to the vicinity of the joint surface of the steel bar or the round bar.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a joining device for joining a steel bar or a round bar to a cruciform joint comprises a holder, a pressing means and a vibration generating means. The holder has a pair of legs and an upper frame, a pressurizing means is fixed to the lower part of the upper frame, a vibration generating means is fixed to one leg, and the steel bar is formed by the pair of legs. Alternatively, the pressurizing means and the vibration generating means are positioned and fixed at the cross-joint portion of the round bar. The pressurizing means has an upsetting hydraulic cylinder fixed to the upper frame of the holder, and presses one intersecting steel bar or round bar from the surface opposite to the joining surface to join the other steel bar or round bar. It is pressed against the surfaces and a bonding pressure is applied to the bonding surfaces. The vibration generating means is composed of an electro-hydraulic servo mechanism and linearly vibrates the joining surface of any one of the steel bars or round bars crossing each other at a predetermined amplitude and frequency. Then, the joining pressure P applied by the pressurizing means and the vibration applied by the vibration generating means generate frictional heat on the joint surface of the steel bar or round bar crossed, and the frictional heat generated causes the joint surface to be in a semi-molten state for joining. The pressure P is applied to bring the joint surfaces into pressure contact.

When joining steel bars or round bars crossed in this way, the joining pressure P for bringing the joining surfaces into pressure contact is 25
Make sure that the joint surface is pressure welded in the range of N / mm ² to 75 N / mm ² . Also, the joining pressure P is set in the range of 25 N / mm ² to 75 N / mm ² , and the vibration applied to the end of the deformed steel bar or round bar is amplitude A = 0.5 mm to ⁵ mm and frequency f = 50 Hz or 250 Hz.
Amplitude A = 0.5 when the joining pressure P is 75 N / mm ²
mm, frequency f = 50 Hz, joint pressure P and amplitude A
And the product of frequency f, P · A · f, exceeds the curve showing a constant value, and the amplitude A when the joining pressure P is 25 N / mm ^2.
= 5 mm, frequency f = 215 Hz as a reference, the product of the joint pressure P, the amplitude A and the frequency f, P · A · f, is set within a range that does not exceed a constant value. The amount of heat applied is increased to reliably bring the joining surface into a semi-molten state, prevent the molten metal from sagging, and form a good joint in a short time.

Further, the vibration time of the joint portion is set in the range of 5 seconds to 60 seconds to prevent the total amount of heat generated from becoming insufficient or excessive.

[0017]

1, 2 and 3 show an embodiment of the present invention. FIG. 1 is a top view, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. 3 is a sectional view taken along line BB of FIG. It is a figure. As shown in the figure, a welding device 4 for welding an intersection 3 of rebars 1 and 2 which intersect vertically and horizontally has a holder 5, a pressing means 6 and a vibration generating means 7. The holder 5 has a pair of legs 51, a plurality of upper frames 52 stretched over the pair of legs 51, and a pedestal 53 provided below the pair of legs 51. As shown in FIG. 2, a guide groove 54 cut out in accordance with the pitch of the reinforcing bar 1 arranged in the longitudinal direction is provided at the lower end of the pair of leg portions 51 in parallel with each other and the lower end of the pedestal 53. Having a pair of legs 5
As shown in FIG. 3, at the lower end along the longitudinal direction of 1,
It has a guide groove 55 that fits into the reinforcing bar 2 arranged in the lateral direction. The pressurizing means 6 has an upset hydraulic cylinder 61 attached to the center of the lower surface of the upper frame 52 of the holder 5 provided at the upper part of one guide groove 54. The upper surface of the vertical reinforcing bar 1 is pressed and pressed against the upper surface of the horizontal reinforcing bar 2.

As shown in the block diagram of FIG. 4, the vibration generating means 7 is a clamping means 71 for gripping the transverse reinforcing bar 2.
And a displacement detector 74 such as a differential transformer for detecting the amount of movement of the electro-hydraulic servo valve 73 and the hydraulic cylinder 72. The vibration generator 7 is connected to the vibration controller 8 and the hydraulic unit 9. Vibration control section 8 for controlling the operation of the vibration generating means 7.
An input unit 81 for inputting the vibration frequency f, the amplitude A and the vibration time T, and a signal generation unit 8 for generating a control signal at the vibration frequency f, the amplitude A and the vibration time T input by the input unit 81.
2 and a feedback amplifier 84 for amplifying the displacement signal from the servo amplifier 83 and the displacement detector 74. An upset hydraulic cylinder 61 is connected to the hydraulic unit 9 via an upset hydraulic cylinder control unit 10. As shown in FIGS. 1 and 3, the vibration generating means 6 is attached inside the one leg portion 41 at a position spaced apart from the upsetting hydraulic cylinder 61 by a certain distance, and vibrates the rebar 2 in the lateral direction. .

When welding the rebars 1 and 2 intersecting with each other in the joining device 1 constructed as described above at the intersection 3, first, the upsetting hydraulic cylinder 61 of the pressurizing means 6 is retracted and the upsetting is performed. The holder 5 is arranged above the rebars 1 and 2 so as to come to the position of the intersection 3 where the hydraulic cylinder 61 joins, and the tip end of the leg portion 51 is attached to the backing plate 11 and the surface plate under the rebars 1 and 2, for example It is fixed by a lock mechanism such as a magnetic attraction plate or a vacuum attraction plate. And the intersection 3 of the horizontal rebar 2
It is gripped by the clamp means 71 of the vibration generating means 7 which is arranged at a position separated by a predetermined distance from or above the intersection.

In this state, a predetermined vibration frequency f, an amplitude A and a vibration time T are input and set in the input section 81 of the vibration control section 8, and a predetermined joining pressure P is set in the upsetting hydraulic cylinder control section 10. Then, the operation of the vibration generating means 7 is started. When the operation of the vibration generator 7 is started, the signal generator 82
Sends a signal Vi corresponding to the set vibration frequency f and amplitude A to the servo amplifier 83. The servo amplifier 83 converts the sent signal Vi into a current I and sends it to the electro-hydraulic servo valve 73. The electro-hydraulic servo valve 73 moves the main spool by the sent current, changes the flow direction of the pressure oil sent to the vibration hydraulic cylinder 72, and moves the piston of the vibration hydraulic cylinder 72. The amount of movement of the vibration hydraulic cylinder 72 is detected by the displacement detector 74, amplified by the amplifier 84 and sent to the servo amplifier 83 as a feedback signal Vf, and the signal Vi and the feedback signal Vf are compared and calculated. , Closed-
Make up the system. Therefore, by sending the signal Vi corresponding to the predetermined vibration frequency f and the amplitude A to the servo amplifier 83, the vibration hydraulic cylinder 72 is made to have the predetermined vibration frequency f.
According to the amplitude A, the horizontal reinforcing bar 2 held by the clamp means 71 is horizontally vibrated in a straight line. Since the horizontal reinforcing bar 2 is thus vibrated, the reinforcing bar 2 can be easily vibrated at an arbitrary frequency.

When the horizontal vibration of the rebar 2 is started by the vibration generating means 7 as described above, the upset hydraulic cylinder 61 is operated by the upset hydraulic cylinder control unit 10 to move the vertical rebar 1 in the horizontal direction. The reinforcing bars 2 are brought into contact with each other and pressurized with a predetermined joining pressure P. Friction heat is generated at the joint surface at the intersection 3 by the joining pressure P and the vibration of the horizontal reinforcing bar 2, and the vertical reinforcing bar 1 is pressed against the horizontal reinforcing bar 2. When the vibration time T set in the input section 81 of the vibration control section 8 has elapsed, the signal Vi sent from the signal generating section 82 to the servo amplifier 83 is set to zero to stop the operation of the vibration hydraulic cylinder 72.

When the longitudinal rebar 1 is joined to the horizontal rebar 2 at the intersection 3, the frictional heat generated per unit time at the joint surface is the joint pressure P, the frequency f of the rebar 2 vibration and the amplitude A. Depends on And to melt the joint surface,
It is necessary that the product P · A · f of the welding pressure P, the vibration amplitude A, and the frequency f, which corresponds to the amount of work due to the friction of the joint surfaces, be equal to or greater than a certain limit value.

For example, the amount of heat Qm required to turn 1 gram of mild steel into a semi-molten state from room temperature to 1500 ° C is 1500 ° C of mild steel.
Qm = 0.17 × 1500 (cal)
become. However, the heating value Qm is 150 for the heating temperature just below the melting point of mild steel.
Since the temperature is 0 ° C., the latent heat of fusion is omitted. Then, for example, the heat quantity Q required to heat the reinforcing bar 2 having the diameter d of the contact surface to the semi-molten state by the capacity up to the depth Lcm is Q = (7.8
・ Π ・ d ²・ L ・ Qm) / 4. Here, 7.8 is the specific gravity of mild steel. If now the ^{L = 0.7cm, Q = 1392πd 2} /4
become. It is necessary to give this required heat quantity Q as the heat quantity Qf generated by friction at the intersection 3 of the reinforcing bars 1 and 2.

The heat quantity Qf generated by friction is Qf = (k
・ F ・ A ・ f ・ t). Where k is the coefficient of friction, F
Is a pressing force, and t is a vibration time. Since the required heat quantity Q is given by the heat quantity Qf generated by this friction, (k · F · A ·
become ^{f · t) = 1392πd 2/} 4. Bonding pressure P is P = F
/ Is given by ([pi] d ^2/4), when a k = 1/100, from the above equation, the bonding pressure P is, P = (1392 × 100) / (A · f ·
given by t).

Here, when the appropriate time of the vibration time of the reinforcing bar 2 is in the range of 5 seconds to 60 seconds, the joining pressure P is P = 27840 /
The range is from (A · f) to P = 2320 / (A · f).

Further, as a result of investigating various conditions necessary for joining with good joint performance, an appropriate joining pressure P is 25 N / m.
It was found to be in the range of m ² (260 kgf / cm ² ) to 75 N / mm ² (770 kgf / cm ² ). That is, when the joining pressure P is less than 25 N / mm ² , the predetermined joining strength cannot be obtained due to insufficient crimping even if the temperature of the joining surface rises due to frictional heat, and the joining pressure P is 75 N / mm 2. ^If it exceeds ² , the whole bonding surface becomes a rough bead, which is not a preferable condition.

Further, the relative displacement amount of the joint surfaces of the reinforcing bars 1 and 2, that is, the amplitude A of vibration was properly in the range of 0.5 mm to 5 mm. That is, if the amplitude A is less than 0.5 mm, the friction surface becomes too small, and it is difficult to obtain the friction heat necessary for joining in a short time, and the softening region becomes too large to obtain a good joint. I couldn't. Also, the amplitude A
If is larger than 5 mm, misalignment is likely to occur at the joint surface and the dimensional accuracy is not good.

Further, the frequency f of vibration is 50 Hz to 250
Hz was in the proper range. That is, it was confirmed that when the frequency is 50 Hz or less, the heating time becomes long, the width of the heating zone becomes large and the performance of the joint deteriorates, and when the frequency exceeds 250 Hz, a normal and smooth joint cannot be obtained. .

Further, the vibration time t of the reinforcing bar 2 varies depending on the size of the reinforcing bar 2 and the required joining strength level, but the range of 5 to 60 seconds is an appropriate time. That is, when the vibration time t is less than 5 seconds, the joint end surface does not rise to the temperature distribution required for joining, a good joint is not obtained, and the vibration time t is
If it exceeds 60 seconds, the friction surface at the joint will overheat,
This is because the heat-affected zone becomes too large and causes material deterioration.

Therefore, the above-mentioned P = 27840 / (A · f) showing the relationship between these various conditions, the welding pressure P for obtaining the heat quantity Q required for welding in the semi-molten state, the amplitude A and the frequency f.
From the range of P to 2320 / (Af), as shown in FIG. 5, the limit for obtaining good joint performance is that the joining pressure P is 25
N / mm ² (260 kgf / cm ² ) to 75 N / mm ² (770 kgf / cm ² ) in the range of vibration amplitude A = 0.5 mm to ⁵ mm, frequency f = 50 Hz
From 250Hz to 250Hz, when the joining pressure P is 75N / mm ² , the amplitude A = 0.5mm and the frequency f = 50Hz are used as the reference. The range exceeds the curve A shown, and the joining pressure P is 25 N / mm ²
With the amplitude A = 5 mm and the frequency f = 215 Hz as the reference, the condition shown in the range of the range where the product P · A · f of the joint pressure P and the amplitude A and the frequency f does not exceed the curve B showing a constant value is optimal. It was a condition.

As a result of setting the conditions for joining in a semi-molten state as described above, a good joint can be obtained with a short vibration time of 5 to 60 seconds, and a good joint is not limited to the welding posture. Can be obtained.

Further, the cooling may be either forced cooling or natural cooling, but if forced cooling is performed in the case of forced cooling, the joint surface becomes too hard and the elongation characteristics become insufficient. Therefore, it is preferable to appropriately control the cooling time. .

Although the above embodiment has described the case where the reinforcing bar 2 is vibrated in the horizontal direction, it may be vibrated in any direction. Further, the vibration may be linear vibration or vibration that draws an arcuate or elliptical locus. Further, although the above-described embodiment has been described with respect to the case where the reinforcing bars 1 and 2 are joined to form the cross joint, the same applies to the case where the steel bars or round bars having the same diameter or different diameters are joined to the cross joint. Can be pressed together.

[0034]

As described above, according to the present invention, one of the steel bars or the round bar is vibrated at a predetermined amplitude and frequency while pressing the joining part at the intersection of the steel bars or the round bar, and the joining pressure P and the vibration are applied. Since frictional heat is generated on the joint surface and the joint surface is pressed by the joint pressure P while the joint surface is in a semi-molten state by the generated frictional heat, the joint surface is pressure-welded, so that crossed steel bars or round bars can be reliably joined. it can.

Further, since one of the steel bars or the round bar is vibrated when forming the cross joint, the vibration can be easily vibrated and the amplitude A and frequency f of the vibration can be arbitrarily changed.

When forming the cruciform joint in this way, as a condition for obtaining the amount of heat Q required for joining in a semi-molten state, the joining pressure P for press-contacting the joining end faces is 25 N.
/ Mm ² to 75 N / mm ² , with vibration amplitude A = 0.5 mm
Amplitude A = 0.5 mm, frequency f = when joining pressure P is 75 N / mm ² in the range of 5 mm, frequency f = 50 Hz to 250 Hz
A range in which the product P · A · f of the joint pressure P, the amplitude A and the frequency f exceeds a curve showing a constant value with 50 Hz as a reference,
When the joint pressure P is 25 N / mm ² , the amplitude A = 5 mm and the frequency f = 215 Hz are used as a reference, and the product P · A · f of the joint pressure P, the amplitude A and the frequency f does not exceed the curve showing a constant value. By doing so, the amount of heat generated per unit time due to the friction of the joint surface can be increased, the joint surface can be reliably melted, and a good joint can be formed in a short time. Therefore, the work efficiency of joining can be significantly improved. Moreover, since the joining is performed in a semi-molten state, a good joint can be obtained regardless of the welding posture.

Further, the vibration time of the steel bar and the round bar is changed from 5 seconds.
By setting the range to 60 seconds and preventing the total amount of heat generated from becoming insufficient or excessive, it is possible to stably form a highly reliable cross joint in a short time.

[Brief description of drawings]

FIG. 1 is a top view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of the embodiment.

FIG. 3 is a sectional view taken along line BB of the above embodiment.

FIG. 4 is a block diagram showing a vibration generating means of the above embodiment.

FIG. 5 is a characteristic diagram showing a relationship between a joining pressure P and a vibration frequency f × amplitude A.

[Explanation of symbols]

 1, 2 Reinforcing bar 3 Intersection 4 Joining device 5 Holder 6 Pressurizing means 7 Vibration generating means 8 Vibration control section 9 Hydraulic unit 61 Upset hydraulic cylinder 71 Clamping means 72 Vibration hydraulic cylinder 73 Electro-hydraulic servo valve 74 Displacement detection vessel

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location E04C 5/04 E04C 5/04 E04G 21/12 105 E04G 21/12 105E (72) Inventor Kiyoteru Hirabayashi 3-16-20-203 Nishioi, Shinagawa-ku, Tokyo

Claims (4)

[Claims] 1. A method for joining crossed steel bars, wherein steel bars or round bars having the same diameter or different diameters are joined to a cross joint,
The lower surface of one steel bar or round bar is brought into pressure contact with the upper surface of the other steel bar or round bar, and vibration is applied to the vicinity of the contact portion of the upper and lower steel bars or round bars, and the contact surface of the upper and lower steel bars or round bar due to the vibration. And a joining surface of upper and lower steel bars or round bars is pressed by frictional heat and pressure generated. 2. A bonding pressure P for bringing the bonding surfaces into pressure contact.
In the range of 25 N / mm ² to 75 N / mm ² , and the vibration amplitude A =
0.5 mm to 5 mm, frequency f = 50 Hz to 250 Hz,
Range where the product P · A · f of the welding pressure P, the amplitude A and the frequency f exceeds a curve showing a constant value, with the amplitude A = 0.5 mm and the frequency f = 50 Hz when the welding pressure P is 75 N / mm ^2. When the joining pressure P is 25 N / mm ² , the amplitude A = 5 mm and the frequency f = 215 Hz are used as the reference, and the product P · A · f of the joining pressure P, the amplitude A and the frequency f exceeds the curve showing a constant value. The method for joining crossed steel bars according to claim 1, which is in a range that does not exist. 3. The method for joining crossed steel bars according to claim 2, wherein the vibration time of the joining surface is set in the range of 5 seconds to 60 seconds. 4. A joining device for crossed steel bars, comprising a holder, a pressurizing means, and a vibration generating means, and joining steel bars or round bars having the same diameter or different diameters to a cross joint, wherein the holder is a pressing means. And the vibration generating means are held and positioned at the cross joint part of the steel bar or round bar, and the pressurizing means has an upsetting hydraulic cylinder fixed to the lower part of the upper frame of the holder. Is pressed from the surface opposite to the joining surface to bring it into pressure contact with the joining surface of the other steel bar or round bar, and the vibration generating means vibrates in the vicinity of the joining surface of either one of the steel bars or round bars that crosses each other. A joining device for crossed steel bars, which is characterized by giving