Electrotinning electrolyte circulating system and control method

Abstract

The invention belongs to the technical field of electrotinning equipment, and discloses an electrotinning electrolyte circulating system which comprises a tin dissolving tank and a control device, a tin adding pipeline, an outer circulating pipeline and an inner circulating pipeline are arranged at the top of the tin dissolving tank, and the inner circulating pipeline of the control device pumps electroplating liquid at the top of the tin dissolving tank of the control device into the bottom of the tin dissolving tank; the control method comprises the following steps: step 1, a tin dissolving circulation system starting step; 2, stopping the tin dissolving circulation system, and adding tin; according to the tin dissolving circulating system, closed-loop control that the rotating speed of the variable-frequency circulating pump is automatically adjusted in real time to keep the flow (flow velocity) in the tin dissolving tank unchanged is adopted, so that tin particles in the tin dissolving tank are prevented from being flushed to the settling tank and wasted, and tin dissolving balance is prevented from being damaged to cause rise of the tin loss rate.

Description

Technical Field

[0001] The invention belongs to the technical field of electrotin plating equipment, and in particular relates to an electrotin plating electrolyte circulation system and a control method. Background Art

[0002] At present, there are two technical deficiencies in the tin dissolving process of electroplated tinplate production: first, the stencil is easily clogged, resulting in huge cost waste and quality loss and other adverse consequences; second, as the tin particles are dissolved, the flow rate will increase, and the oxygen flow rate will also need to be changed artificially due to the production of different products. These two points (increased flow rate and changes in oxygen flow rate) will cause waste of tin particles and an increase in tin loss rate.

[0003] In the tin dissolving process of electroplating tinplate production, there are two stages that are prone to clogging the stencil:

[0004] During the dissolution process, these tin particles are lifted by the high-speed, bottom-up liquid and suspended to a higher position above the stencil. These tin particles are dissolved into tin ions (Sn2+) and become less. After a period of time, the circulation needs to be stopped to replenish the tin particles. When the circulation is stopped, several tons of tin particles lose the support of the liquid and smash down to the stencil at a very fast speed at a higher position. This is the first stage that is easy to block the stencil.

[0005] After replenishing the tin particles, it is necessary to start the circulation to dissolve the tin. At this time, the tin particles that leaked to the bottom of the stencil and the tin particles that were previously brought to the bottom of the stencil by the self-circulation will be pushed to the stencil from bottom to top by the high-speed liquid. This is the second stage that is easy to clog the stencil.

[0006] Once the stencil is clogged, there are only two solutions: one is to take out the tons of tin particles in the tin dissolving tank, remove the stencil from the tin dissolving tank, and then poke or drill thousands of stencil holes one by one, and then reinstall the stencil and tin particles; the other is to adjust the tin dissolving parameters and continue to dissolve the tin to slowly dissolve the tin particles in the stencil holes.

[0007] Obviously, the first approach requires a lot of manpower, material resources and 1 day of time. At this time, the tin dissolving system cannot work at all, and the production line cannot get any tin ion supply and will shut down quickly, so this approach is generally not adopted. The second approach also takes several hours to 1 day, and there is still a small amount of tin ion supply to the production line, but there is also the possibility of product quality defects, forced speed reduction or even shutdown. In addition, at this time, oxygen will gather under the stencil in large quantities. These excess oxygen will inevitably oxidize the expensive tin ions (Sn2+) in the solution that will be used for electroplating into worthless or even harmful tin mud to product quality, resulting in great cost waste and quality loss.

[0008] In short, it takes a lot of time to deal with the blockage of the stencil, during which time there is the possibility of product quality defects, forced speed reduction or even shutdown, which will also cause huge cost waste and quality loss.

[0009] In addition, as the tin dissolving reaction proceeds, the tin particles in the tin dissolving tank are gradually consumed, that is, the weight of the tin particles in the tin dissolving tank gradually decreases over time. In the fixed-frequency pump circulation system currently commonly used in the market, because the speed of the fixed-frequency pump is constant, as the weight of the tin particles in the tin dissolving tank decreases, the resistance of the tin dissolving system also decreases, and the flow rate (flow rate) in the tin dissolving tank will naturally increase. Furthermore, due to process requirements, the oxygen flow rate will need to be changed artificially due to different products produced, which will also affect the flow rate (flow rate) in the tin dissolving tank. The increase in flow rate will not only cause some tin particles to be washed into the precipitation tank and wasted, but also destroy the balance of tin dissolving, causing the tin consumption rate to increase. The decrease in flow rate may also destroy the balance of tin dissolving, causing the tin consumption rate to increase. Summary of the invention

[0010] In order to solve the above problems existing in the prior art, the present invention aims to provide a control method for a tin electroplating electrolyte circulation system.

[0011] The technical solution adopted by the present invention is:

[0012] A tin electroplating electrolyte circulation system comprises a tin dissolving tank, wherein the top of the tin dissolving tank is respectively provided with a tin adding pipeline, an external circulation pipeline and an internal circulation pipeline, wherein the internal circulation pipeline extracts the electroplating solution at the top of the tin dissolving tank into the bottom thereof, and the external circulation pipeline extracts the electroplating solution at the top of the tin dissolving tank into a plating solution storage tank, wherein the plating solution storage tank is provided with a liquid supply pipeline, wherein the plating solution storage tank is connected to the internal circulation pipeline through the liquid supply pipeline, wherein a liquid discharge pipeline is provided near the middle of the tin dissolving tank, wherein the tin dissolving tank is connected to the external circulation pipeline through the liquid discharge pipeline, and wherein the plating solution storage tank receives the electroplating solution from the production line and outputs it into the production line after circulating and adding tin;

[0013] The external circulation pipeline is provided with an external circulation automatic valve, an external circulation flowmeter and a sedimentation tank in sequence according to the flow direction of the electroplating solution; the tin adding pipeline is provided with a tin adding hopper and a tin adding automatic valve; the liquid unloading pipeline is provided with a liquid unloading valve; the liquid supply pipeline is provided with a liquid supply pump, and the internal circulation pipeline is provided with a circulation flow control device, a mixer and an internal circulation flowmeter in sequence according to the flow direction of the electroplating solution, one input end of the mixer is connected to the oxygen supply pipeline, and the oxygen supply pipeline is provided with an oxygen regulating valve.

[0014] Furthermore, the circulation flow control device is a variable frequency circulation pump.

[0015] Furthermore, the circulation flow control device includes a fixed-frequency circulation pump, a bypass pipeline is connected between the top of the tin dissolving tank and the internal circulation pipeline, the bypass pipeline is provided with a bypass regulating valve, and the bypass pipeline is connected to the internal circulation pipeline near the output end of the fixed-frequency circulation pump.

[0016] On the other hand, two control methods are designed according to the different design structures of this circulation system.

[0017] A control method for a tin electroplating electrolyte circulation system comprises the following steps:

[0018] Step 1: Start the tin dissolving circulation system

[0019] Step 11: Continuously transfer the plating solution in the plating solution storage tank to the tin dissolving tank

[0020] Step 12: When the tin dissolving liquid level meter detects that the liquid level in the tin dissolving tank or the flow rate of the external circulation flow meter reaches a preset value, the circulation flow control device is started to control the flow rate of the electroplating solution to gradually increase over time until the flow rate reaches the preset value and then maintain the preset flow value unchanged.

[0021] Step 13: Open the oxygen regulating valve, mix the oxygen and the plating solution in the mixer, and then transport them to the tin dissolving tank to react with the tin particles.

[0022] Step 2: Stop the tin dissolving circulation system and add tin

[0023] Step 21, closing the oxygen regulating valve to stop supplying oxygen to the tin dissolving tank;

[0024] Step 22, stopping the liquid feed pump and stopping supplying the plating solution to the tin dissolving tank;

[0025] Step 23, controlling the flow rate of the plating solution to gradually decrease to zero through a circulation flow control device;

[0026] Step 24, opening the liquid unloading valve to unload the plating solution in the tin dissolving tank into the plating solution storage tank;

[0027] Step 25, when the tin dissolving tank level meter detects that the liquid level in the tin dissolving tank is lower than the preset value, the liquid unloading is completed, and the tin adding automatic valve is opened to add tin into the tin dissolving tank.

[0028] Furthermore, in step S11, the plating solution in the plating solution storage tank is transported to the tin dissolving tank, and the tin adding automatic valve and the liquid unloading valve need to be closed, the external circulation automatic valve is opened, and the liquid feeding pump is started.

[0029] Furthermore, in step S12, the circulation flow control device is a variable frequency circulation pump, which runs at a relatively low speed at the initial start-up, and then gradually increases its speed as time goes by, and its speed is closed-loop controlled according to a pre-set time-flow. The flow is detected in real time by an internal circulation flow meter, and the set flow gradually increases with time until the flow reaches a certain predetermined value and the predetermined flow value is maintained unchanged.

[0030] Furthermore, in step S23, the speed of the variable frequency circulation pump is gradually reduced, and its speed is closed-loop controlled according to the pre-set time-flow. The flow is detected in real time by the internal circulation flow meter. The set flow is gradually reduced over time until the flow is zero.

[0031] A second control method for a tin electroplating electrolyte circulation system comprises the following steps:

[0032] Step 1: Start the tin dissolving circulation system

[0033] Step 11: Continuously transfer the plating solution in the plating solution storage tank to the tin dissolving tank

[0034] Step 12: When the tin dissolving liquid level meter detects that the liquid level in the tin dissolving tank or the flow rate of the external circulation flow meter reaches a preset value, the circulation flow control device is started to control the flow rate of the electroplating solution to gradually increase over time until the flow rate reaches the preset value and then maintain the preset flow value unchanged.

[0035] Step 13: Open the oxygen regulating valve, mix the oxygen and the plating solution in the mixer, and then transport them to the tin dissolving tank to react with the tin particles.

[0036] Step 2: Stop the tin dissolving circulation system and add tin

[0037] Step 21, closing the oxygen regulating valve to stop supplying oxygen to the tin dissolving tank;

[0038] Step 22, stopping the liquid feed pump and stopping supplying the plating solution to the tin dissolving tank;

[0039] Step 23, controlling the flow rate of the plating solution to gradually decrease to zero through a circulation flow control device;

[0040] Step 24, opening the liquid unloading valve to unload the plating solution in the tin dissolving tank into the plating solution storage tank;

[0041] Step 25, when the tin dissolving tank level meter detects that the liquid level in the tin dissolving tank is lower than the preset value, the liquid unloading is completed, and the tin adding automatic valve is opened to add tin into the tin dissolving tank.

[0042] Furthermore, in step S11, the plating solution in the plating solution storage tank is transported to the tin dissolving tank, and the tin adding automatic valve, the liquid unloading valve, the external circulation automatic valve, the internal circulation regulating valve, and the bypass regulating valve are closed. The liquid feed pump is started to continuously transport the plating solution in the plating solution storage tank to the tin dissolving tank.

[0043] Furthermore, in step S12, the fixed-frequency circulation pump is started, and the opening of the inner circulation regulating valve is gradually and slowly increased, while the opening of the bypass regulating valve is gradually and slowly decreased. Closed-loop control is performed according to a pre-set time and flow rate. The flow rate is detected in real time by an inner circulation flow meter, and gradually increases with time until the flow rate reaches a preset value and then the preset flow rate value is maintained unchanged.

[0044] Furthermore, in step S23, the opening of the bypass regulating valve is gradually and slowly increased, and the opening of the inner circulation regulating valve is gradually and slowly decreased, and the closed-loop control is performed according to the pre-set time-flow. The flow is detected in real time by the inner circulation flow meter. The set flow gradually decreases with the passage of time until the flow is zero. At this time, the opening of the inner circulation regulating valve is zero, that is, closed, and then the fixed-frequency circulation pump is stopped.

[0045] The beneficial effects of the present invention are:

[0046] 1. The tin dissolving circulation system of the present invention adopts a closed-loop control that automatically adjusts the speed of the variable frequency circulation pump in real time to keep the flow rate (flow velocity) in the tin dissolving tank unchanged, thereby preventing the tin particles in the tin dissolving tank from being washed into the precipitation tank and wasted, and preventing the balance of the tin dissolving from being destroyed to cause an increase in the tin loss rate.

[0047] 2. The tin dissolving circulation system of the present invention adopts a closed-loop control for adjusting the opening degree of the inner circulation regulating valve and the opening degree of the bypass regulating valve to keep the flow rate (flow velocity) in the tin dissolving tank unchanged, thereby preventing the tin particles in the tin dissolving tank from being washed into the precipitation tank and wasted, and preventing the tin dissolving balance from being destroyed to cause an increase in the tin loss rate;

[0048] By setting up an internal circulation flow meter, an internal circulation regulating valve, a bypass regulating valve and controlling the opening degree of the internal circulation regulating valve and the bypass regulating valve in two stages, the flow of the tin dissolving tank is controlled according to the pre-set time and flow rate to avoid stencil blockage. During the tin dissolving process, a closed-loop control is adopted to automatically adjust the opening degree of the internal circulation regulating valve and the bypass regulating valve in real time to keep the flow (flow rate) in the tin dissolving tank unchanged, thereby avoiding the waste of tin particles being washed into the precipitation tank and maintaining the balance of tin dissolving. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of the overall structure of the first embodiment of the present invention;

[0050] Figure 2 It is a schematic diagram of the overall structure of the second embodiment of the present invention.

[0051] Figure numerals; among them, 1, tin dissolving tank; 2, sedimentation tank; 3, plating solution storage tank; 4, oxygen regulating valve; 5, mixer; 6, internal circulation flow meter; 7, liquid supply pump; 8, liquid unloading valve; 9, variable frequency circulation pump; 10, external circulation flow meter; 11, external circulation automatic valve; 12, tin adding bucket; 13, tin adding automatic valve; 14, tin dissolving level meter; 15, fixed frequency circulation pump; 16, bypass regulating valve; 100, tin adding pipeline; 200, external circulation pipeline; 300, liquid unloading pipeline; 400, liquid supply pipeline; 500, oxygen supply pipeline; 600, internal circulation pipeline; 700, bypass pipeline. DETAILED DESCRIPTION

[0052] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0053] Example 1

[0054] like Figure 1 As shown, a tin electroplating electrolyte circulation system comprises a tin dissolving tank 1, the top of the tin dissolving tank 1 is respectively provided with a tin adding pipeline 100, an external circulation pipeline 200 and an internal circulation pipeline 600, the internal circulation pipeline 600 extracts the electroplating solution on the top of the tin dissolving tank 1 into the bottom thereof, the external circulation pipeline 200 extracts the electroplating solution on the top of the tin dissolving tank 1 into a plating solution storage tank 3, the plating solution storage tank 3 is provided with a liquid supply pipeline 400, the plating solution storage tank 3 is connected to the internal circulation pipeline 600 through the liquid supply pipeline 400, the tin dissolving tank 1 is provided with a liquid discharge pipeline 300 near the middle, the tin dissolving tank 1 is connected to the external circulation pipeline 200 through the liquid discharge pipeline 300, the plating solution storage tank 3 receives the electroplating solution from the production line and outputs it into the production line after circulating and adding tin;

[0055] The external circulation pipeline 200 is provided with an external circulation automatic valve 11, an external circulation flowmeter 10 and a sedimentation tank 2 in sequence according to the flow direction of the electroplating solution; the tin adding pipeline 100 is provided with a tin adding bucket 12 and a tin adding automatic valve 13; the liquid unloading pipeline 300 is provided with a liquid unloading valve 8; the liquid supply pipeline 400 is provided with a liquid supply pump 7, and the internal circulation pipeline 600 is provided with a circulation flow control device, a mixer 5 and an internal circulation flowmeter 6 in sequence according to the flow direction of the electroplating solution, one input end of the mixer 5 is connected to the oxygen supply pipeline 500, and the oxygen supply pipeline 500 is provided with an oxygen regulating valve 4.

[0056] A tin adding hopper 12 is arranged above the tin dissolving tank 1, and the tin adding hopper 12 is used to temporarily store the tin particles to be added to the tin dissolving tank 1. An automatic tin adding valve 13 is arranged between the tin adding hopper 12 and the tin dissolving tank 1, and the automatic tin adding valve 13 is controlled by a control device to open and close.

[0057] An external circulation automatic valve 11 and an external circulation flow meter 10 are provided on the pipeline connecting the tin dissolving tank 1 and the settling tank 2. The external circulation automatic valve 11 is controlled by the control device to open and close. The external circulation flow meter 10 transmits the measured flow value to the control device. The liquid feed pump 7 delivers the plating liquid in the plating liquid storage tank 3 to the tin dissolving tank 1 through the mixer 5 and the internal circulation flow meter 6. As the liquid feed pump 7 continuously delivers the plating liquid, the plating liquid in the tin dissolving tank 1 flows through the pipeline at the top of the tin dissolving tank 1, the external circulation automatic valve 11, the external circulation flow meter 10, the settling tank 2, and finally returns to the plating liquid storage tank 3, thereby realizing external circulation.

[0058] The tin dissolving tank 1 extracts the plating solution at the top of the tin dissolving tank 1 through the variable frequency circulation pump 9 and transports it to the mixer 5 and the internal circulation flowmeter 6 to the bottom of the tin dissolving tank 1, thereby realizing self-circulation, that is, internal circulation. The variable frequency circulation pump 9 is variable frequency, and its speed is adjustable and controllable, rather than constant. The internal circulation flowmeter 6 measures the flow of the plating solution in the pipeline and transmits the flow value to the control device.

[0059] There is mutual plating solution exchange between the production line and the plating solution storage tank 3 so that the whole system provides high-concentration plating solution to the production line, and the production line delivers low-concentration plating solution to the plating solution storage tank 3 .

[0060] A liquid unloading pipeline is arranged in the middle of the tin dissolving tank 1 and leads to the plating solution storage tank 3. A liquid unloading valve 8 is arranged on the pipeline. The opening and closing of the liquid unloading valve 8 is controlled by a control device. The power of liquid unloading comes from gravity.

[0061] The oxygen regulating valve 4 controls the flow of oxygen entering the mixer 5, and the oxygen regulating valve 4 is controlled by a control device.

[0062] The tin dissolving tank 1 is provided with a tin dissolving liquid level meter 14, which is used to detect the liquid level in the tin dissolving tank 1 and transmit the liquid level detection value to the control device. The tin dissolving tank 1 is provided with a mesh plate.

[0063] The control method of the tin dissolving circulation system of the present embodiment 1 comprises the following steps:

[0064] Step 1: Start-up phase of the tin dissolving circulation system:

[0065] Step 11, close the tin adding automatic valve 13, close the liquid unloading valve 8, and open the external circulation automatic valve 11. Start the liquid feeding pump 7 to continuously transport the plating liquid in the plating liquid storage tank 3 to the tin dissolving tank 1;

[0066] Step 12, when the tin dissolving liquid level meter 14 detects that the liquid level in the tin dissolving tank 1 reaches a certain value and (or) the flow rate of the external circulation flow meter 10 reaches a certain value, the variable frequency circulation pump 9 is started. The variable frequency circulation pump 9 runs at a relatively low speed at the initial start-up, and then gradually increases the speed as time goes by. The speed is closed-loop controlled according to a preset time-flow rate. The flow rate is detected in real time by the internal circulation flow meter 6. The set flow rate gradually increases with the passage of time until the flow rate reaches a certain preset value and then keeps the preset flow rate value unchanged;

[0067] In this step, the flow rate in the tin dissolving tank 1 is slowly increased according to a pre-set time-flow relationship, rather than reaching the maximum instantly from zero, so that the tin particles of different sizes under the stencil rise slowly one after another to approach the stencil, and then pass through the stencil, rather than all the tin particles being shot upward and squeezed toward the stencil like a shotgun, causing the stencil to be blocked.

[0068] Step 13, open the oxygen regulating valve 4, mix the oxygen and the plating solution in the mixer 5, and then transport them to the tin dissolving tank 1 to react with the tin particles. During the tin dissolving reaction, the speed of the variable frequency circulation pump 9 is automatically adjusted in real time according to the value detected by the internal circulation flow meter 6 to maintain the flow rate (flow rate) in the tin dissolving tank 1 constant;

[0069] In addition, during the tin dissolving process, as the tin dissolving reaction proceeds, the tin particles in the tin dissolving tank 1 are gradually consumed, that is, the weight of the tin particles in the tin dissolving tank 1 gradually decreases over time. In the fixed-frequency pump circulation system currently commonly used on the market, because the speed of the fixed-frequency pump is constant, as the weight of the tin particles in the tin dissolving tank 1 decreases, the resistance of the tin dissolving system also decreases, and the flow rate (flow rate) in the tin dissolving tank 1 will naturally increase. Moreover, due to process requirements, the oxygen flow rate will need to be artificially changed due to different products produced, which will also affect the flow rate (flow rate) in the tin dissolving tank 1. The increase in flow rate will not only cause part of the tin particles to be washed to the precipitation tank 2 and wasted, but also destroy the balance of tin dissolving and cause the tin consumption rate to increase, and the decrease in flow rate may also destroy the balance of tin dissolving and cause the tin consumption rate to increase. The internal circulation flowmeter 6 detects the flow in real time, and adjusts the speed of the variable frequency circulation pump 9 in real time according to the detection value of the internal circulation flowmeter 6 and the predetermined value of the internal circulation flow to achieve the stability of the internal circulation flow, that is, the closed-loop control of the detection value of the internal circulation flowmeter 6 is achieved by adjusting the speed of the variable frequency circulation pump 9;

[0070] Step 2: Add tin particles, that is, stop the tin dissolving circulation system

[0071] As the tin dissolving reaction proceeds, the tin particles in the tin dissolving tank 1 are gradually consumed. When the tin particles are consumed to a certain extent, tin particles need to be added.

[0072] Step 21, closing the oxygen regulating valve 4 to stop supplying oxygen to the tin dissolving tank 1;

[0073] Step 22, stop the liquid supply pump 7, and stop supplying the plating solution to the tin dissolving tank 1;

[0074] Step 23, gradually reduce the speed of the variable frequency circulation pump 9, and the speed is closed-loop controlled according to the pre-set time and flow rate. The flow rate is detected in real time by the internal circulation flow meter 6. The set flow rate is gradually reduced over time until the flow rate is zero. At this time, the variable frequency circulation pump 9 enters a stopped state;

[0075] In this step, the tin particles that were originally lifted by the high-speed, bottom-up liquid and suspended at a higher position above the stencil will slowly lower their height due to the gradual decrease in the liquid flow rate until they slowly fall onto the stencil, instead of being blocked by the stencil due to the sudden stop of the fixed-frequency pump circulation system currently used in the market.

[0076] Step 24, opening the liquid unloading valve 8 to unload the plating solution in the tin dissolving tank 1 into the plating solution storage tank 3;

[0077] Step 25 , when the tin dissolving liquid level meter 14 detects that the liquid level in the tin dissolving tank 1 is lower than a certain value, the liquid unloading is completed, and at this time, the tin adding automatic valve 13 is opened to add tin into the tin dissolving tank 1 .

[0078] The tin dissolving circulation system adopts a closed-loop control that automatically adjusts the speed of the variable frequency circulation pump 9 in real time to keep the flow rate (flow velocity) in the tin dissolving tank 1 unchanged, thereby preventing the tin particles in the tin dissolving tank 1 from being washed into the precipitation tank 2 and wasted, and also preventing the tin dissolving balance from being destroyed to cause an increase in the tin loss rate.

[0079] Embodiment 2:

[0080] like Figure 2 As shown, a tin electroplating electrolyte circulation system comprises a tin dissolving tank 1, the top of the tin dissolving tank 1 is respectively provided with a tin adding pipeline 100, an external circulation pipeline 200 and an internal circulation pipeline 600, the internal circulation pipeline 600 extracts the electroplating solution on the top of the tin dissolving tank 1 into the bottom thereof, the external circulation pipeline 200 extracts the electroplating solution on the top of the tin dissolving tank 1 into a plating solution storage tank 3, the plating solution storage tank 3 is provided with a liquid supply pipeline 400, the plating solution storage tank 3 is connected to the internal circulation pipeline 600 through the liquid supply pipeline 400, the tin dissolving tank 1 is provided with a liquid discharge pipeline 300 near the middle, the tin dissolving tank 1 is connected to the external circulation pipeline 200 through the liquid discharge pipeline 300, the plating solution storage tank 3 receives the electroplating solution from the production line and outputs it into the production line after circulating and adding tin;

[0081] The external circulation pipeline 200 is provided with an external circulation automatic valve 11, an external circulation flowmeter 10 and a sedimentation tank 2 in sequence according to the flow direction of the electroplating solution; the tin adding pipeline 100 is provided with a tin adding bucket 12 and a tin adding automatic valve 13; the liquid unloading pipeline 300 is provided with a liquid unloading valve 8; the liquid supply pipeline 400 is provided with a liquid supply pump 7, and the internal circulation pipeline 600 is provided with a circulation flow control device, a mixer 5 and an internal circulation flowmeter 6 in sequence according to the flow direction of the electroplating solution, one input end of the mixer 5 is connected to the oxygen supply pipeline 500, and the oxygen supply pipeline 500 is provided with an oxygen regulating valve 4.

[0082] The circulation flow control device includes a fixed-frequency circulation pump 15 , a bypass pipeline 700 is connected between the top of the tin dissolving tank 1 and the internal circulation pipeline 600 , the bypass pipeline 700 is provided with a bypass regulating valve 16 , and the bypass pipeline 700 is connected to the internal circulation pipeline 600 near the output end of the fixed-frequency circulation pump 15 .

[0083] A tin adding hopper 12 is arranged above the tin dissolving tank 1, and the tin adding hopper 12 is used to temporarily store the tin particles to be added to the tin dissolving tank 1. An automatic tin adding valve 13 is arranged between the tin adding hopper 12 and the tin dissolving tank 1, and the automatic tin adding valve 13 is controlled by a control device to open and close;

[0084] An external circulation automatic valve 11 and an external circulation flow meter 10 are arranged on the pipeline connecting the tin dissolving tank 1 and the sedimentation tank 2. The external circulation automatic valve 11 is controlled by the control device to be opened and closed. The external circulation flow meter 10 transmits the measured flow value to the control device. The liquid feed pump 7 transports the plating liquid in the plating liquid storage tank 3 to the tin dissolving tank 1 through the mixer 5 and the internal circulation flow meter 6. As the liquid feed pump 7 continuously transports the plating liquid, the plating liquid in the tin dissolving tank 1 flows through the pipeline on the top of the tin dissolving tank 1 in turn through the external circulation automatic valve 11, the external circulation flow meter 10, the sedimentation tank 2, and finally returns to the plating liquid storage tank 3, thereby realizing external circulation.

[0085] The tin dissolving tank 1 extracts the plating solution on the top of the tin dissolving tank 1 through the fixed-frequency circulation pump 15 and transports it to the internal circulation regulating valve, the mixer 5, the internal circulation flowmeter 6 to the bottom of the tin dissolving tank 1, thereby realizing self-circulation, that is, internal circulation. The fixed-frequency circulation pump 15 is conventionally fixed-frequency, and its speed is non-adjustable and constant, that is, it has only two states: start and stop. The internal circulation flowmeter 6 measures the flow of the plating solution in the pipeline and transmits the flow value to the control device. The internal circulation regulating valve can adjust the opening size, and its opening size is controlled by the control device.

[0086] A bypass pipe is provided, one end of which is connected to the outlet of the fixed frequency circulation pump 15 and the other end is connected to the tin dissolving tank 1. A bypass regulating valve 16 is provided on the bypass pipe. The bypass regulating valve 16 can adjust the opening size, and the opening size is controlled by the control device.

[0087] There is mutual plating solution exchange between the production line and the plating solution storage tank 3 so that the whole system provides high-concentration plating solution to the production line, and the production line delivers low-concentration plating solution to the plating solution storage tank 3 .

[0088] A liquid unloading pipeline is arranged in the middle of the tin dissolving tank 1 and leads to the plating solution storage tank 3. A liquid unloading valve 8 is arranged on the pipeline. The opening and closing of the liquid unloading valve 8 is controlled by a control device. The power of liquid unloading comes from gravity.

[0089] The oxygen regulating valve 4 controls the flow of oxygen entering the mixer 5, and the oxygen regulating valve 4 is controlled by a control device.

[0090] The tin dissolving tank 1 is provided with a tin dissolving liquid level meter 14, which is used to detect the liquid level in the tin dissolving tank 1 and transmit the liquid level detection value to the control device. The tin dissolving tank 1 is provided with a mesh plate.

[0091] The control method of the tin dissolving circulation system of Example 2 comprises the following steps:

[0092] Step 1: Start-up phase of the tin dissolving circulation system:

[0093] Step 11, close the tin adding automatic valve 13, close the liquid unloading valve 8, open the external circulation automatic valve 11, close the internal circulation regulating valve, open the bypass regulating valve 16, start the liquid feeding pump 7, and continuously transport the plating liquid in the plating liquid storage tank 3 to the tin dissolving tank 1;

[0094] Step 12, when the tin dissolving liquid level meter 14 detects that the liquid level in the tin dissolving tank 1 reaches a certain value and (or) the flow rate of the external circulation flow meter 10 reaches a certain value, the fixed frequency circulation pump 15 is started, and the opening degree of the internal circulation regulating valve is gradually and slowly increased, and the opening degree of the bypass regulating valve 16 is gradually and slowly decreased. Closed-loop control is performed according to the pre-set time and flow rate. The flow rate is detected in real time by the internal circulation flow meter 6. The set flow rate gradually increases with the passage of time until the flow rate reaches a certain predetermined value and then keeps the predetermined flow rate unchanged;

[0095] In this step, the flow rate in the tin dissolving tank 1 is slowly increased according to the pre-set time-flow relationship, rather than reaching the maximum from zero in an instant, so the tin particles of different sizes under the stencil rise slowly and approach the stencil one after another, and then pass through the stencil, rather than all the tin particles being shot upward and squeezed toward the stencil like a shotgun, thereby clogging the stencil;

[0096] Step 13, open the oxygen regulating valve 4, mix the oxygen and the plating solution in the mixer 5 and then transport them to the tin dissolving tank 1 to react with the tin particles to dissolve the tin. During the tin dissolving reaction, the opening degree of the internal circulation regulating valve and the opening degree of the bypass regulating valve 16 are automatically adjusted in real time according to the value detected by the internal circulation flowmeter 6 to maintain the flow rate (flow rate) in the tin dissolving tank 1 constant.

[0097] In addition, during the tin dissolving process, as the tin dissolving reaction proceeds, the tin particles in the tin dissolving tank 1 are gradually consumed, that is, the weight of the tin particles in the tin dissolving tank 1 gradually decreases over time. In the conventional tin dissolving circulation system currently on the market, since the speed of the fixed frequency pump is constant and there is no other adjustment means, as the weight of the tin particles in the tin dissolving tank 1 decreases, the resistance of the tin dissolving system also decreases, and the flow rate (flow velocity) in the tin dissolving tank 1 will naturally increase;

[0098] Furthermore, due to process requirements, the oxygen flow rate may need to be changed artificially due to the different products produced, which will also affect the flow rate (flow rate) in the tin dissolving tank 1. The increase in flow rate will not only cause part of the tin particles to be washed to the precipitation tank 2 and wasted, but also destroy the tin dissolving balance and cause the tin consumption rate to increase. The decrease in flow rate may also destroy the tin dissolving balance and cause the tin consumption rate to increase. The internal circulation flow meter 6 detects the flow rate in real time, and automatically adjusts the opening degree of the internal circulation regulating valve and the opening degree of the bypass regulating valve 16 in real time according to the detection value of the internal circulation flow meter 6 and the predetermined value of the internal circulation flow to achieve the stability of the internal circulation flow, that is, the closed-loop control of the detection value of the internal circulation flow meter 6 is achieved by adjusting the opening degree of the internal circulation regulating valve and the opening degree of the bypass regulating valve 16.

[0099] Step 2, adding tin particles, that is, stopping the tin dissolving circulation system:

[0100] As the tin dissolving reaction proceeds, the tin particles in the tin dissolving tank 1 are gradually consumed. When the tin particles are consumed to a certain extent, tin particles need to be added.

[0101] Step 21, closing the oxygen regulating valve 4 to stop supplying oxygen to the tin dissolving tank 1;

[0102] Step 22, stop the liquid supply pump 7, and stop supplying the plating solution to the tin dissolving tank 1;

[0103] Step 23, gradually and slowly increase the opening of the bypass regulating valve 16, and at the same time gradually and slowly decrease the opening of the inner circulation regulating valve, and perform closed-loop control according to the pre-set time-flow. The flow is detected in real time by the inner circulation flow meter 6. The set flow gradually decreases with the passage of time until the flow is zero. At this time, the opening of the inner circulation regulating valve is zero, that is, it is in the closed state, and then, the fixed-frequency circulation pump 15 is stopped.

[0104] In this step, the tin particles that were originally lifted by the high-speed, bottom-up liquid and suspended above the stencil will slowly lower their height until they slowly fall onto the stencil due to the gradual decrease in the liquid flow rate, instead of being blocked by the stencil due to the sudden stop of the fixed-frequency pump as in the conventional tin dissolving circulation system on the market.

[0105] Step 24, opening the liquid unloading valve 8 to unload the plating solution in the tin dissolving tank 1 into the plating solution storage tank 3;

[0106] Step 25 , when the tin dissolving liquid level meter 14 detects that the liquid level in the tin dissolving tank 1 is lower than a certain value, the liquid unloading is completed, and at this time, the tin adding automatic valve 13 is opened to add tin into the tin dissolving tank 1 .

[0107] In summary, the tin dissolving circulation system provided by the present invention adopts a closed-loop control for adjusting the opening degree of the inner circulation regulating valve and the opening degree of the bypass regulating valve 16 to keep the flow rate (flow velocity) in the tin dissolving tank 1 unchanged, thereby preventing the tin particles in the tin dissolving tank 1 from being washed into the precipitation tank 2 and wasted, and preventing the tin dissolving balance from being destroyed to cause an increase in the tin loss rate;

[0108] By setting the inner circulation flow meter 6, the inner circulation regulating valve, the bypass regulating valve 16 and controlling the opening degree of the inner circulation regulating valve and the bypass regulating valve 16 in two stages, the flow of the tin dissolving tank 1 is controlled according to the pre-set time-flow to avoid the stencil blockage. In the tin dissolving process, the inner circulation regulating valve opening degree and the bypass regulating valve 16 opening degree are automatically adjusted in real time to keep the flow (flow rate) in the tin dissolving tank 1 unchanged. The closed-loop control is adopted to avoid the waste of tin particles being washed into the precipitation tank 2 and maintain the balance of tin dissolving.

[0109] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A tin electroplating electrolyte circulation system, characterized in that: It comprises a tin dissolving tank, the top of which is respectively provided with a tin adding pipeline, an external circulation pipeline and an internal circulation pipeline, the internal circulation pipeline extracts the electroplating solution on the top of the tin dissolving tank into the bottom thereof, the external circulation pipeline extracts the electroplating solution on the top of the tin dissolving tank into a plating solution storage tank, the plating solution storage tank is provided with a liquid supply pipeline, the plating solution storage tank is connected to the internal circulation pipeline through the liquid supply pipeline, the tin dissolving tank is provided with a liquid discharge pipeline near the middle, the tin dissolving tank is connected to the external circulation pipeline through the liquid discharge pipeline, the plating solution storage tank receives the electroplating solution from the production line and outputs it into the production line after circulating and adding tin; The external circulation pipeline is provided with an external circulation automatic valve, an external circulation flowmeter and a sedimentation tank in sequence according to the flow direction of the electroplating solution; the tin adding pipeline is provided with a tin adding hopper and a tin adding automatic valve; the liquid unloading pipeline is provided with a liquid unloading valve; the liquid supply pipeline is provided with a liquid supply pump, and the internal circulation pipeline is provided with a circulation flow control device, a mixer and an internal circulation flowmeter in sequence according to the flow direction of the electroplating solution, one input end of the mixer is connected to the oxygen supply pipeline, and the oxygen supply pipeline is provided with an oxygen regulating valve.

2. The tin electroplating electrolyte circulation system according to claim 1, characterized in that: The circulation flow control device is a variable frequency circulation pump.

3. The tin electroplating electrolyte circulation system according to claim 1, characterized in that: The circulation flow control device includes a fixed-frequency circulation pump. A bypass pipeline is connected between the top of the tin dissolving tank and the internal circulation pipeline. The bypass pipeline is provided with a bypass regulating valve. The bypass pipeline is connected to the internal circulation pipeline near the output end of the fixed-frequency circulation pump.

4. A control method for a tin electroplating electrolyte circulation system, applied to the tin electroplating electrolyte circulation system according to any one of claims 2 to 3, characterized in that: The following steps are involved: Step 1: Start the tin dissolving circulation system Step 11: Continuously transfer the plating solution in the plating solution storage tank to the tin dissolving tank Step 12, when the tin dissolving liquid level meter detects that the liquid level in the tin dissolving tank or the flow rate of the external circulation flow meter reaches a preset value, the circulation flow control device is started to control the flow rate of the electroplating solution to gradually increase over time until the flow rate reaches a preset value and then maintain the preset flow rate value unchanged; Step 13, opening the oxygen regulating valve, mixing the oxygen and the plating solution in the mixer and then transporting them to the tin dissolving tank to react with the tin particles; Step 2, stopping the tin dissolving circulation system and adding tin; Step 21, closing the oxygen regulating valve to stop supplying oxygen to the tin dissolving tank; Step 22, stopping the liquid supply pump and stopping supplying the plating solution to the tin dissolving tank; Step 23, controlling the flow rate of the plating solution to gradually decrease to zero through a circulation flow control device; Step 24, opening the liquid unloading valve to unload the plating solution in the tin dissolving tank into the plating solution storage tank; Step 25, when the tin dissolving tank level meter detects that the liquid level in the tin dissolving tank is lower than the preset value, the liquid unloading is completed, and the tin adding automatic valve is opened to add tin into the tin dissolving tank.

5. The control method of a tin electroplating electrolyte circulation system according to claim 4, characterized in that: In the step S11, the plating solution in the plating solution storage tank is transported to the tin dissolving tank. It is necessary to close the tin adding automatic valve, close the liquid unloading valve, open the external circulation automatic valve, and start the liquid feeding pump.

6. The control method of a tin electroplating electrolyte circulation system according to claim 5, characterized in that: In step S12, the circulation flow control device is a variable frequency circulation pump, which runs at a lower speed at the initial start-up, and then gradually increases the speed as time goes by. The speed is closed-loop controlled according to a pre-set time-flow; the flow is detected in real time by an internal circulation flow meter, and the set flow gradually increases with time until the flow reaches a certain predetermined value and then maintains this predetermined flow value unchanged.

7. The control method of a tin electroplating electrolyte circulation system according to claim 6, characterized in that: In step S23, the speed of the variable frequency circulation pump is gradually reduced, and its speed is closed-loop controlled according to a preset time-flow; the flow is detected in real time by an internal circulation flow meter; the set flow is gradually reduced over time until the flow is zero.

8. The control method of a tin electroplating electrolyte circulation system according to claim 4, characterized in that: In the step S11, the plating solution in the plating solution storage tank is transported to the tin dissolving tank. It is necessary to close the tin adding automatic valve, close the liquid unloading valve, open the external circulation automatic valve, close the internal circulation regulating valve, and open the bypass regulating valve; start the liquid feeding pump to continuously transport the plating solution in the plating solution storage tank to the tin dissolving tank.

9. The control method of a tin electroplating electrolyte circulation system according to claim 8, characterized in that: In step S12, the fixed-frequency circulation pump is started, and the opening of the inner circulation regulating valve is gradually and slowly increased, while the opening of the bypass regulating valve is gradually and slowly decreased. Closed-loop control is performed according to the pre-set time and flow rate. The flow rate is detected in real time by the inner circulation flow meter, and gradually increases with the passage of time until the flow rate reaches the preset value and then the preset flow rate value is maintained unchanged.

10. The control method of a tin electroplating electrolyte circulation system according to claim 9, characterized in that: In step S23, the opening of the bypass regulating valve is gradually and slowly increased, and the opening of the inner circulation regulating valve is gradually and slowly decreased, and the closed-loop control is performed according to the pre-set time-flow rate; the flow rate is detected in real time by the inner circulation flow meter; the set flow rate gradually decreases with the passage of time until the flow rate is zero, at which time the opening of the inner circulation regulating valve is zero, that is, in a closed state, and then the fixed-frequency circulation pump is stopped.

Images