CN102935552B - Flash welding forming method of constructional steel thin-wall ring member - Google Patents

Abstract

The invention discloses a flash welding forming method of a structural steel thin-walled ring. The steps include: loading a D-shaped ring blank with an opening into a welding machine, starting the welding machine to close the opening of the preheated ring blank, A voltage of 7V-18V is applied between the two poles, so that the left and right end faces at the opening of the ring blank pass through a current density of 15A/mm ² ～220A/mm ^2. The flash current heats up and melts to form a lintel and explodes to form a flash; the flash of the ring blank The burning speed is 3.6mm~7.2mm/s, and the right end face of the driving ring blank is accelerated to the left end face at an initial speed of 2.5mm/s~4.0mm/s and an acceleration of 1.0mm/s ² ～2.0mm/s ² Feed movement, so as to ensure that the distance between the left and right end faces is ≤ 7mm; after the flashing is completed, the right straight edge of the ring blank is driven to move to the left straight edge at high speed, and the left, right, and The right end faces collide together to form a flash welded thin-walled ring, which is kept under pressure for 10s to 30s under the action of the upsetting force. The method can make the flash process go on continuously and stably, thereby improving the quality of the weld seam.

Description

Flash Welding Forming Method of Structural Steel Thin-walled Ring

technical field

The invention relates to a welding method, in particular to a flash welding forming method of a structural steel thin-walled ring.

Background technique

With the increasing demand for rings in industries such as aviation, aerospace, ships, gas turbines, wind energy, nuclear energy, and bearings, rings formed by traditional rolling methods not only waste a lot of materials due to large machining allowances and low material utilization , but also keeps the cost of ring parts high. The ring parts produced by the flash welding process have less machining allowance, high material utilization rate, and greatly reduce the cost, which is conducive to the development of ring forming technology in the direction of precision forming technology.

The Chinese invention patent specification CN 1233548A published on November 3, 1999 discloses a flash welding process for aluminum alloy wheels of automobiles and motorcycles. The technological process adopted for the wheels is: pretreatment → welding condition setting → clamping workpiece → flashing → upsetting → holding pressure → loose clamp → trimming, which solves the technical problem of welding and forming aluminum alloy wheel rings, and the wheels are thin-walled rings. However, in the process of welding thin-walled rings such as structural steel thin-walled rings by flash welding, if the distance between the two ends of the ring blank weld is not well controlled, the flash will stop, which will affect the continuous process of welding and the quality of the weld. , In severe cases, it will cause the weldment to be scrapped.

Contents of the invention

The technical problem to be solved by the present invention is to provide a flash welding forming method of structural steel thin-walled rings by keeping a certain distance between the two ends of the weld during welding. To carry out, thereby improving welding quality.

In order to solve the above-mentioned technical problems, the flash welding forming method of structural steel thin-walled rings according to the present invention, its technical solution includes the following steps:

Put the structural steel D-shaped ring blank with opening into a flash butt welding machine with a power of 1000KVA, so that the straight sides on the left and right sides of the opening are respectively clamped by the electrodes on the left and right sides of the welding machine. The device is clamped with a clamping force of 5KN ~ 8KN;

Apply a voltage of 7 to 18V between the electrodes on the left and right sides of the flash butt welding machine, start the moving platen to drive the clamping device on the right side to move in parallel on the machine base, so that the left and right sides of the D-shaped ring blank opening The right two ends contact quickly and then separate quickly to form intermittent flashes to preheat the left and right two ends. After the left and right two ends contact and separate 45 to 75 times, each power-on time is 0.02s. , and the right two ends are heated to 1180±20°C respectively;

Start the welding machine to drive the right straight edge of the D-shaped ring blank to move toward the left straight edge to close the opening of the ring blank, and apply a welding voltage of 7V to 18V between the two stages of the welder to make the The small contact points on the left end face and the right end face of the opening of the ring billet are heated and melted by a flash current with a current density of 15A/mm ² ~ 220A/mm ² , forming a liquid lintel connecting the metals at both ends and blasting to a high speed. The external injection forms a flash, and the burning speed of the flash between the left and right end surfaces is 3.6mm/s～7.2mm/s; then drive the right end surface at the opening of the ring blank to the left end surface at a speed of 2.5mm/s～4.0mm/s The initial speed of mm/s and the acceleration of 1.0mm/s ² ~ 2.0mm/s ² are used for accelerated feed motion, and the liquid lintel is continuously formed between the left end surface and the right end surface and continuously blasted, and the left end surface and the right end surface are continuously blasted. The distance between the surfaces is ≤7mm, and the flashing process continues until the predetermined flashing allowance of 15mm to 25mm is reached after 3s to 5s of flashing time. covered by a thin layer of molten metal;

Drive the right straight edge of the D-shaped ring blank to move to the left straight edge at a high speed of 80mm/s~120mm/s, so that the upsetting force of the right and left end faces after flash sintering is 9KN~15KN Impacted together under the action, the ring blank is upset into a flash welded thin-walled ring;

The thin-walled ring is disassembled from the welding machine after maintaining the pressure for 10s to 30s under the action of the upsetting force.

During the flashing process, the relationship between the initial feed speed, the flashing acceleration and the flashing burning speed of the right end at the opening of the D-shaped ring blank to the left end face is as follows:

$V_1\≤V_0+\sqrt{14a},$ In the formula:

V ₁ ——flashing burning speed (mm/s);

V ₀ ——Initial velocity (mm/s) when the right end of the opening of the D-shaped ring blank is fed to the left end during the flashing process;

a——flash acceleration (mm/s ² );

The structural steel is preferably 38CrA alloy.

The axial cross-sectional dimension of the ring is at most 65mm×30mm.

Compared with the prior art, the beneficial effects of the present invention are as follows:

In the flash welding forming method of structural steel thin-walled rings according to the present invention, the distance between the left end face and the right end face of the opening of the D-shaped ring blank must be less than or equal to a certain value during the welding process, so as to ensure that the contact points are continuously melted and burned. The flash blasts out, which is necessary for molten metal to form lintels. For the flash butt welding machine with a power of 1000KVA used in the present invention, under the given process parameters, this certain value is equal to 7mm, therefore, the distance between the left end face and the right end face must be ≤ 7mm to ensure the flash The process continues to improve the welding quality; if the distance between the left end face and the right end face is greater than 7mm, the molten metal will not be able to form a lintel, resulting in an open circuit during the flash process, which will cause the flash to stop, affect the welding progress and may cause welding The piece is scrapped.

During the flashing process, since the feed speed V ₂ of the right end face of the D-shaped ring blank opening to the left end face gradually increases with time, and the flash burning speed V ₁ is constant under the given process parameters Therefore, V ₂ < V ₁ at the initial stage of flashing, the distance between the left end face and the right end face increases continuously, and when the distance between the left end face and the right end face = 7mm, it reaches the point where the molten metal forms a lintel Critical value, V ₂ =V ₁ ; if you continue to flash under the condition of V ₂ <V ₁ at this time, the distance between the left end face and the right end face will be >7mm, and the distance between the left end face and the right end face Just can't form lintel and produce open circuit, flashing stops. Therefore, when the distance between the left end face and the right end face reaches 7mm, the flashing must be continued under the condition of V ₂ >V ₁ , so that the distance between the left end face and the right end face can be gradually reduced, so that the flashing process It can be carried out continuously and stably until the contact surface of the left and right end surfaces is covered by a very thin layer of molten metal until the flashing process ends.

Assuming that the initial speed of feeding the right end face to the left end face is V ₀ , then:

Formula ①: V ₂ =V ₀ +at;

Since the distance lost by the flashing of the left and right end faces is V ₁ t, the feed distance of the right end face to the left end face is To make the distance between the left end face and the right end face ≤ 7mm, then:

Formula ②: $V_{1}t-(V_{0}t+\frac{1}{2}{\mathrm{at}}^2)\&le;7$

When the distance=7mm between the left end face and the right end face reaches the critical value of molten metal forming a lintel, then:

Formula ③: V ₂ =V ₁

From the above formulas ① to ③, it can be deduced that:

Therefore, during the flashing process, if the initial feed speed flash acceleration and flash burning speed from the right end face to the left end face at the opening of the D-shaped ring blank meet Thus, the flash welding process of the ring can be performed continuously and stably, and a welded portion with good performance can be obtained.

Taking the structural steel thin-walled ring with the grade of 38CrA as an example, after heat treatment, the room temperature tensile properties of the welded part of the alloy thin-walled ring were tested, and the tensile strength was 825MPa (greater than the design requirement of 796.5MPa), and the elongation after fracture was 7 % (greater than 6% of the design requirements).

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is a schematic diagram of loading a D-shaped ring blank into a flash butt welding machine.

Figure 2 is a schematic diagram of the flashing stage of the D-ring blank.

Fig. 3 is a schematic diagram after flashing at the opening of the D-ring blank.

Fig. 4 is a schematic diagram of upsetting at the opening of the D-shaped ring blank.

Fig. 5 is a schematic diagram of a thin-walled ring formed by welding.

Detailed ways

To implement the flash welding forming method of structural steel thin-walled rings according to the present invention, it is necessary to provide flash butt welding machines, manipulators and other equipment. The specific implementation of the method will be described in detail below by taking the structural steel whose material grade is 38CrA in my country as an example:

The main chemical element content (percentage by weight) of the alloy is: C content 0.34%-0.42%, Mn content 0.50%-0.80%, Si content 0.17%-0.37%, S content ≤ 0.015%, P content ≤0.025%, Cr content 0.08%～1.10%, Ni content ≤0.40%, Cu content ≤0.25, balance Fe.

The flash welding forming process steps of the alloy thin-walled ring are as follows:

Step 1: Install the computer. As shown in Figure 1, the 38CrA alloy D-shaped ring blank with openings is loaded into a flash butt welding machine with a power of 1000KVA. The opening 110 has a left end face 111 on the side corresponding to the left straight side 101 , and a right end face 112 on the side corresponding to the right straight side 102 . During installation, put the left side straight edge 101 of the D-shaped ring blank into the left clamping device 10 of the flash butt welding machine, and the upper clamp 11 and the lower clamp 12 (electrode clamp 10) of the left clamping device 10 ) clamp the left straight side 101 from the upper and lower end surfaces of the left side straight side 101 respectively, and the clamping force is 5KN～8KN; put the right side straight side 102 of the D-shaped ring blank into the right side of the flash butt welding machine In the side clamping device 20, the upper and lower clamps 21 and 22 (electrodes) of the right clamping device 20 respectively clamp the right side straight side 102 from the upper and lower end surfaces of the right side straight side 102, and the clamping force It is 5KN～8KN, so that the upper and lower end surfaces and the front and rear end surfaces of the left straight side 101 and the right side straight side 102 are respectively aligned. The left clamping device 10 is installed on the fixed platen 30 of the flash butt welding machine, the right clamping device 20 is installed on the movable platen 40 of the flash butt welder, and the fixed platen 30 and the movable platen 40 are installed On the base of the flash butt welding machine, the movable platen 40 can drive the clamping device 20 on the right side to move back and forth in parallel on the base toward the fixed platen 30 to open or close the opening 110 of the D-ring blank.

Step 2: Preheat. Apply a voltage of 7-18V between the left lower clamp 12 (electrode) and the right lower clamp 22 (electrode) of the flash butt welding machine, and start the moving platen 40 to drive the right clamping device 20 on the machine base The upper and lower parallel movement makes the left end face 111 and the right end face 112 at the opening 110 of the D-shaped ring blank quickly contact and separate quickly, forming intermittent flashes to preheat the left end face 111 and the right end face 112, the opening 110 is closed and After being separated for 45-75 times, the left end surface 111 and the right end surface 112 are respectively heated to 1180±20° C. for 0.02 s each time.

Step 3: Glitter. As shown in Figure 2, start the movable platen 40 to drive the right clamping device 20 to move towards the fixed platen on the machine base, so that the left end face 111 and the right end face 112 at the opening 110 of the D-shaped ring blank contact the rear opening 110 In the closed state; apply a welding voltage of 7V to 18V between the two stages of the flash butt welding machine, and the small contact points on the left end surface 111 and the right end surface 112 will flash due to the current density of 15A/mm ² to 220A/mm ² The current passes through to form a resistance and generate heat. The metals at these contact points are quickly melted to form a liquid "lining" connecting the metals at both ends. These liquid "linings" are blasted under the combined action of electricity, heat, and force, and are sprayed outward at high speed. A flash is formed, and the burning speed of the flash between the left and right end surfaces is 3.6 mm/s to 7.2 mm/s; after that, the moving platen 40 moves toward the direction of the fixed platen so that the right end face 112 at the opening 110 of the D-shaped ring blank The left end face 111 performs an accelerated feed motion with an initial speed of 2.5 mm/s to 4.0 mm/s and an acceleration of 1.0 mm/s ² to 2.0 mm/s ² . lintel" and continuous blasting, the distance between the left end face 111 and the right end face 112 is always kept ≤ 7mm, and the flashing process continues until the predetermined flashing allowance of 15 mm to 25 mm is reached after 3s to 5s of flashing time, and the flashing When the process is over, as shown in Figure 3, the two end surface contact surfaces of the left end surface 111' and the right end surface 112' after flash firing are covered by a layer of very thin molten metal, and the temperature of the two end surface contact surfaces reaches the melting point of the metal, and tends to stable and even.

During the flashing process, in order to keep the flashing process going on continuously and stably, the initial feed speed and flashing acceleration from the right end face 112 to the left end face 111 at the opening 110 of the D-shaped ring blank should match the flashing burning speed, namely:

$V_1\&le;V_0+\sqrt{14a},$ In the formula:

V ₁ ——flashing burning speed (mm/s);

V ₀ ——Initial velocity (mm/s) when the right end of the opening of the D-shaped ring blank is fed to the left end during the flashing process;

a——flash acceleration (mm/s ² );

Since the power of the flash butt welding machine is a certain value, after setting the welding parameters, the energy applied by the flash butt welding machine to the welding end face during the flashing process is also a certain value. Therefore, in the case of a given material, the flash burning speed And flash acceleration is also a certain value.

Step 4: Upsetting. As shown in Figure 4, after the flashing is over, the movable platen 40 drives the clamping device 20 on the right side to move at a high speed of 80 mm/s to 120 mm/s in the direction of the fixed platen on the machine base, and the D-ring blank is flashed. After sintering, the two ends of the left end face 111' and the right end face 112' collide together under the action of an upsetting force F of 9KN ~ 15KN, and the molten metal and metal oxides between the two ends are all pushed out to the surface of the workpiece. The two contact surfaces of the surface 111' and the right end surface 112' are plastically deformed so that the metal on the two end surfaces is in close contact with the metal, and the D-shaped ring blank is formed by upset forging into a flash welded thin-walled ring 200 as shown in Figure 5. The thin-walled ring 200 has a welding portion 201 .

Step 5: Hold the pressure. Hold the welded thin-walled ring 200 under the action of upsetting force for 10s-30s, and then disassemble it from the flash butt welding machine after the weld seam is fully combined.

The 38CrA structural steel thin-walled ring welded by the above method has a maximum axial cross-sectional size of 65mm×30mm, where 65mm refers to the height of the ring along the axial direction, and 30mm refers to the wall thickness of the ring along the radial direction.

Claims (4)

1. a flash welding manufacturing process for constructional steel thin-wall ring, is characterized in that, comprise the following steps:

It is the flash butt welder of 1000KVA that the structural steel D shape ring base of band opening is put into power, and the straight flange of its opening part arranged on left and right sides is clamped with the clamping force of 5KN ~ 8KN by the electroded clamping device of the arranged on left and right sides of described welding machine respectively;

The voltage of 7 ~ 18V is applied between the arranged on left and right sides electrode of described flash butt welder, starting mobile platen drives clamping device left and right on support in right side to move in parallel, the left and right both ends of the surface of D type ring base opening part are contacted rapidly, separate rapidly again, form interrupted flash of light and preheating is carried out to left and right both ends of the surface, described left and right both ends of the surface contact and separately after 45 ~ 75 times, each conduction time 0.02s, described left and right both ends of the surface are heated to 1180 ± 20 DEG C respectively;

The right side straight flange starting described welding machine driving D shape ring base moves towards straight flange direction, left side and the opening of described ring base is closed, apply the weldingvoltage of 7V ~ 18V at two interpolars of described welding machine, make the fine contact point on the left side of described ring base opening part and right side be 15A/mm by current density ²~ 220A/mm ²exothermic melting after flashing current, formation connects the liquid lintel of two ends metal and outwards sprays formation flash of light at a high speed after there is explosion, and the flash of light scaling loss speed between described left and right both ends of the surface is 3.6mm/s ~ 7.2mm/s; Then the right side of described ring base opening part is driven towards left side with the initial velocity of 2.5mm/s ~ 4.0mm/s and 1.0mm/s ²~ 2.0mm/s ²acceleration do accelerate feed motion, constantly liquid lintel and continuous explosion is formed between described left side and right side, distance≤7mm between described left side and right side, flash of light process lasts carries out, until reach predetermined flash loss 15mm ~ 25mm after the flash time of 3s ~ 5s, flash of light process terminates, and by motlten metal that one deck very thin is covered between the left side after being burnt and right side by flash of light;

The right side straight flange of D type ring base is driven to move in straight flange direction to the left with the speed of 80mm/s ~ 120mm/s high speed, make described burnt by flash of light after the upset force effect at 9KN ~ 15KN of right side and left side under impinge upon together with, described ring base is configured as flash welding thin-walled ring by upset;

Described thin-walled ring takes apart from welding machine after pressurize 10s ~ 30s under the effect of upset force.

2. the flash welding manufacturing process of constructional steel thin-wall ring according to claim 1, is characterized in that, described flash of light scaling loss speed meets the following conditions:

in formula:

V ₁---flash of light scaling loss speed (mm/s);

V ₀---in flash of light process, the right side of D type ring base opening part is to the initial velocity (mm/s) during the feeding of left side;

A---flash of light acceleration (mm/s ²).

3. the flash welding manufacturing process of constructional steel thin-wall ring according to claim 1, is characterized in that: described structural steel is 38CrA.

4. the flash welding manufacturing process of the constructional steel thin-wall ring according to any one of claims 1 to 3, is characterized in that: the axial cross section size of described ring is maximum is 65mm × 30mm.