Preheat flash butt welding method

Abstract

The present invention discloses a preheat flash butt welding method including fixture clamping, flash flattening stage, preheating stage, continuous flashing stage, upset stage and reset stage, and controls the advance and retreat of the moving fixture in the flash flattening stage, preheating stage and continuous flashing stage according to the relationship between the welding current and the threshold current, and determines the flash flattening starting point according to the distance between the moving fixture and the stationary fixture when the welding current is larger than the threshold current for the first time in this stage, and similarly determines the starting point of continuous flashing in the continuous flashing stage. The present invention can automatically determine the flash flattening starting point, more accurately realize the flash flattening, and avoid material waste, and controls the advance and retreat of the moving fixture and the amount of further preheat compression according to the relationship between the welding current and the threshold current in the preheating stage, so that the preheating is stable, the material consumption is small, the advance speed of the continuous flashing stage is proportional to the flashing distance, and the effect of accelerating the flashing is generated, and the energy accumulation is fast, the flashing is not easily interrupted, and the material consumption is small, and ensures that the optimal flashing speed is reached at the end of the flashing.

Description

[Technical Field]

[0001] The present invention relates to machining techniques, and more particularly to a preheat flash butt welding method. [Background technology]

[0002] Marine anchor chains and mooring anchor chains are chains that connect anchors to ship hulls or marine engineering equipment. With the increasing demand for marine resources around the world and the destruction of marine resource exploration and oil production facilities and mooring units due to poor sea conditions and natural weather, such as tsunamis, hurricanes, and frequent earthquakes in the seas in recent years, the demand for high-level mooring chains for marine engineering is constantly increasing. With the progress of marine development, the operation of mooring units such as new marine platforms and related marine engineering structures is beginning, and the demand for high-level mooring chains as an essential safety component for marine oil production and mining equipment fixing devices is becoming increasingly greater.

[0003] Chinese Patent No. 201080048430.0 discloses a flash butt welding method for rail steel that limits the heat-affected width of the weld joint head to 27 mm or less by specifying the current flow time during the preheating process, thereby preventing significant impact on the rail's structural performance. Chinese Patent No. 201910407841.7 discloses a flash butt welding method for hard alloy cutting tools. During preheating before welding, the workpiece ports are contacted and separated multiple times until all ports are heated to the rated temperature, limiting the current flow time each time. For intermittent flash butt welding, the initial speed and acceleration of the moving clamp are set to accelerate forward movement, and the upset speed is adopted only after a predetermined flash remaining amount is reached. However, the preheating step is not adjusted to meet actual working conditions. For example, the preheating process cannot control the threshold current, resulting in interruption of the flash step due to insufficient temperature, resulting in alternating subsequent flash steps and preheating, further resulting in uncontrollable fusion length. The flash acceleration stage is not adjusted to the actual melting situation, which is likely to affect the quality of the welded joint. Summary of the Invention [Problem to be solved by the invention]

[0004] OBJECT OF THE INVENTION: The object of the present invention is to provide a preheat flash butt welding method that adjusts according to actual working conditions. [Means for solving the problem]

[0005] Technical solution: The preheating flash butt welding method according to the present invention includes a jig clamping stage, a flash flattening stage, a preheating stage, a continuous flashing stage, an upset stage, and a reset stage. In the flash flattening stage, the advancement and retreat of the moving jig is controlled based on the relationship between the welding current i and the threshold current I in each of the flash flattening stage, the preheating stage, and the continuous flashing stage. In the flash flattening stage, when the welding current is greater than the threshold current for the first time in this stage, the flash flattening starting point is determined based on the distance between the moving jig and the stationary jig, and similarly the continuous flash starting point in the continuous flashing stage is determined.

[0006] Furthermore, the flash planarization step comprises: A step (2.1) of energizing the electrodes; a step (2.2) of determining the start point of flash flattening, in which the moving jig advances at a speed of ν0, and when the welding current i becomes greater than I for the first time, the moving jig stops, determining the start point of flash flattening, and at this time, setting the distance i0 between the moving jig and the stationary jig at the start of flash flattening to =1; Step (2.3) in which the moving jig retreats at a speed of -ν0 until i≦I when i>I, and advances at a speed of ν0 until i>I when i≦I, thereby achieving flush flattening; Determine the flush flattening distance and check if the current distance l between the moving jig and the stationary jig is > i0-L a (L a is the flash flattening length), the process returns to step (2.3) and the flash flattening stage ends in step (2.4).

[0007] Furthermore, the preheating step Step (3.1) of setting n to 0, The moving jig advances at a speed of ν1, and when i > I, it continues to advance by a preheating compression amount Δp at a speed of ν1 so as to bring the end faces of the two workpieces to be welded into closer contact. Step (3.2) Step (3.3) where the moving jig stops for a time t1 Step (3.4) where the moving jig retreats at a speed of -ν1 until i ≤ I The moving jig is at time t s Step (3.5) of stopping n := n + 1, and when n < N (N is the rated number of preheating times), it returns to (3.2), and conversely, step (3.6) of ending the preheating stage.

[0008] The continuous flash stage includes: Step (4.1) of determining the starting point of the continuous flash, where the moving jig advances at a speed of ν3, and when i ≤ I, the moving jig stops, determines the starting point of the continuous flash, and at this time, sets the distance i1 between the moving jig and the stationary jig at the start of the continuous flash to = l. Step (4.1) When i > I, until i ≤ I, the moving jig

Number

Number

Number

Number

Number

number

[0009] The upsetting step comprises: Set t to 0, and the initial distance between the moving jig and the stationary jig at the start of upset

number

number

number

[0010] The reset step comprises: A step (6.1) of releasing the moving jig and the stationary jig; The moving jig returns to the initial position and the welding process ends (step 6.2). [Effects of the Invention]

[0011] The beneficial effects are as follows: Compared with the prior art, the notable advantages of the present invention are as follows: 1. In the flash flattening stage, the present invention automatically determines the starting point of flash flattening based on the electrode position where the welding current is first greater than the threshold current, thereby more accurately achieving flash flattening and avoiding material waste. 2. In the preheating stage, the advancement and retreat of the moving jig and the amount of further preheat compression are controlled based on the relationship between the welding current i and the threshold current I, resulting in stable preheating and low material consumption. 3. The advancement speed of the successive flashing stages is proportional to the flashing distance, thereby accelerating the flashing, resulting in fast energy accumulation, less flash interruption, and less material consumption, and ensuring that the optimal flashing speed is reached at the end of the flashing stage. 4. The present invention automatically identifies the welding start position and ensures consistent length after welding. 5. The flash flattening stage of the present invention avoids the problems of uneven heating and flash discontinuity caused by uneven or inconsistent end faces of the workpieces to be welded. 6. The number of preheating stages can be controlled to increase consistency of input energy, reduce material loss, and ensure the continuous progress of subsequent successive flashings. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a flowchart of the present invention. [Figure 2] FIG. 1 is a typical electrode position signal diagram during preheat flash butt welding. [Figure 3] FIG. 1 is a typical current signal diagram during preheat flash butt welding. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present invention will be further described below in conjunction with the drawings.

[0014] The welding parameters related to the preheat flash butt welding method described in the present invention are the welding current i, the current distance l between the moving jig and the stationary jig, and the initial distance l between the moving jig and the stationary jig at the start of flash flattening.

number

number

number

number

[0015] The specific steps are as follows:

[0016] (1) Jig clamping: The pair of workpieces to be welded are clamped in a moving jig and a stationary jig separated by l0 (80 mm), and the current distance l between the moving jig and the stationary jig and the welding current i are monitored in real time during welding.

[0017] (2) Flash flattening stage: (2.1) Apply electricity to the electrodes.

[0018] (2.2) Determine the flash flattening starting point: The moving jig advances at a speed of ν0 (1 mm / s), and when the welding current i reaches > (450 A) for the first time, the moving jig stops. The flash flattening starting point is determined. At this time, the distance between the moving jig and the stationary jig at the start of flash flattening is

number

[0019] (2.3) If i > I(450A), the moving jig retreats at a speed of -ν0 (-1 mm / s) until i ≦ I(450A), and if i ≦ I(450A), the moving jig advances at a speed of ν0 (1 mm / s) until i > I(450A), and flush flattening begins.

[0020] (2.4) Determine the flush flattening distance, and determine the current distance l between the moving jig and the stationary jig.

number

[0021] (3) Preheating stage: (3.1) Set n = 0.

[0022] (3.2) The moving jig moves forward at a speed of ν1 (10 mm / s), and when i>I (450 A), it continues to move forward by Δp (0.5 mm) at a speed of ν1 (10 mm / s) to bring the end faces of the two workpieces to be welded into closer contact, as shown by s1 in Figure 2.

[0023] (3.3) The moving jig stops for time t1 (2 s), as shown by s2 in FIG.

[0024] Until (3.4) i ≤ I (450 A), the moving jig retreats at a speed of -ν1 (-10 mm / s), as shown by s3 in FIG. 2.

[0025] (3.5) The moving jig stops for a time t2 (1 s), as shown by s4 in FIG. 2.

[0026] (3.6) n := n + 1. When n < N (9), it returns to (3.2), and conversely, the preheating stage ends.

[0027] (4) Continuous flash stage: (4.1) Determine the starting point of continuous flashing: The moving jig moves forward at a speed of ν3 (2 mm / s). When i > I (450 A), the moving jig stops, determining the starting point of continuous flashing. At this time, the initial distance between the moving jig and the stationary jig at the start of continuous flashing

Number

[0028] (4.2) When i > I (450 A), until i ≤ I (450 A), the moving jig

Number

Number

[0029] (4.3) Determine the distance of continuous flashing,

Number

Number

number

[0030] (5) Upset Phase: (5.1) Set t = 0, and set the initial distance between the moving jig and the stationary jig at the start of the upset.

number

[0031] (5.2) The moving jig advances at an upset speed of ν4 (35 mm / s) and performs charge upset. At this time, t≧t u The currently elapsed time t continues to be recorded until it reaches (0.2 s), which is shown as s5 in FIG.

[0032] (5.3) The welding current is switched off.

[0033] (5.4) The moving jig is upset at a speed of ν4 (35 mm / s).

number

[0034] (5.5) Moving jig

number

[0035] (6) Reset phase: (6.1) Release the moving fixture and stationary fixture.

[0036] (6.2) The moving jig returns to the initial distance l0 (80 mm) and the welding process ends. [Explanation of symbols]

[0037] In the figure, s1 - forward, s2 - heating, s3 - backward, s4 - balance, s5 - powered upset, s6 - powered upset

Claims

1. 1. A preheat flash butt welding method comprising:

1. A preheating flash butt welding method comprising: a jig clamping stage, a flash flattening stage, a preheating stage, a continuous flashing stage, an upset stage, and a reset stage; wherein the advancement and retreat of the movable jig is controlled based on the relationship between the welding current i and a threshold current I in each of the flash flattening stage, the preheating stage, and the continuous flashing stage; and wherein the flash flattening starting point is determined based on the distance between the movable jig and the stationary jig when the welding current is greater than the threshold current for the first time in this flash flattening stage; and similarly, the starting point of continuous flashing in the continuous flashing stage is determined.

2. The flash planarization step comprises: A step (2.1) of energizing the electrodes; In the step (2.2) of determining the flush flattening starting point, the moving jig is moved to v 0 When the welding current i becomes greater than I for the first time, the moving jig stops and determines the starting point of flash flattening. At this time, the distance between the moving jig and the stationary jig at the start of flash flattening is [Equation 25] Step (2.2) to set = l; When i>I, the moving jig moves to -ν 0 When i≦I, the moving jig moves backward at a speed of v 0 a step (2.3) of flash flattening by advancing at a speed of Determine the flush flattening distance, and the current distance l between the moving jig and the stationary jig is [Equation 26] (L a is the flush flattening length), go back to step (2.3) and [0000] 2. The method of claim 1, further comprising the step (2.4) of terminating the flash flattening step if

3. The preheating step comprises: Step (3.1) of setting n to 0; The moving jig is ν 1 When i>I, the speed of the workpiece is increased to bring the end faces of the two workpieces into closer contact with each other. 1 Step (3.2) of continuing to advance by the preheat compression amount Δp at a speed of The moving jig moves at time t 1 a stopping step (3.3); Until i≦I, the moving jig moves to -ν 1 Step (3.4) of retreating at a speed of The moving jig moves at time t 2 a stopping step (3.5); and a step (3.6) of returning to (3.2) if n:=n+1 and n<N (where N is the rated number of preheats), and terminating the preheating step if n=N.

4. The successive flash steps include: A step (4.1) of determining the starting point of successive flashes, in which the moving jig is moved to v 3 When the speed of the moving jig reaches i>I, the moving jig stops and determines the starting point of the continuous flash. At this time, the distance between the moving jig and the stationary jig at the start of the continuous flash is [0000] Step (4.1) to set = l; If i>I, the moving jig moves until i≦I. [0000] When i≦I, the moving jig moves backward at a speed of [Equation 30] (4.2) a step of continuously flashing forward at a speed of Determine the distance of successive flashes, [Equation 31] In the case of , return to (4.2) and [Equation 32] When the moving jig is ν 3 It moves forward at a uniform speed of [Equation 33] Step (4.3) when L b is the melting length, [Equation 34] 2. The method of claim 1, further comprising the step (4.3) of:

5. The upsetting step comprises: Set t to 0, and set the initial distance between the moving jig and the stationary jig at the start of upsetting. [Equation 35] Step (5.1) to set = l; The moving jig is ν 4 and perform charge upset, and at this time, t≧t u (t u (5.2) continuing to record the currently elapsed time t until A step (5.3) of switching off the welding current; The moving jig is ν 4 at a speed of [Equation 36] (L c (5.4) moving forward to the point (where ∇ is the upset length); The moving jig moves at time t m (t m is the upset sustain time) [Equation 37] 2. The method of claim 1, further comprising the step (5.5) of remaining stationary at the welding point.

6. The reset step comprises: A step (6.1) of releasing the moving jig and the stationary jig; 6. The preheat flash butt welding method according to claim 1, further comprising a step (6.2) in which the moving jig returns to the initial position and the welding process is completed.

Images