A powder coating uniform spreading shaft with variable coating amount

Abstract

A powder coating uniform spreading shaft with variable coating amount comprises a screw body (10) and a plurality of sleeves (20) of different thicknesses, wherein the surface of the screw body (10) is provided with a screw ridge (11); the sleeve (20) comprises a sleeve body (21) and a flange portion (22) coaxially and integrally connected to the sleeve body connection end, the sleeve body (21) is provided with a spiral groove (23) having the same pitch (S) and helical lead angle (α) as the screw ridge (11) and penetrating the sleeve body wall thickness, the spiral groove (23) spirally extending out of the free end of the sleeve body; the sleeve (20) extends into the spiral groove (23) through the screw ridge (11) and is spirally fitted outside the screw body (10), so that the empty portion of the spiral groove becomes a powder filling groove (22); the variable coating amount is achieved by selecting sleeves of different thicknesses to cooperate with the screw ridges to obtain different depths of the powder filling groove (22). The coating powder uniformly spreading shaft with variable coating amount can change the coating amount and provide uniform coating.

Description

Technical Field

[0001] The invention belongs to the technical field of welding pipe powder spraying production, and in particular relates to a spraying powder uniform spreading shaft with a variable spraying amount. Background Art

[0002] Using powder coating as pipeline anti-corrosion coating is currently considered to be an effective method. Many countries in the United States and Europe have used it in oil pipelines for many years. There are three basic requirements for the coating characteristics of powder coating: ① The coating has no pinholes. The pinholes in the coating are a series of small holes similar to pinholes formed on the surface of the coating, also known as missed coating points. Or microbubbles appear in the coating, and the microbubbles burst, resulting in extremely thin coating thickness at that location, or even small missed coating points. The presence of pinholes in the coating not only affects the appearance quality of the product, but also seriously affects the mechanical properties and protective properties of the product. Most of the corrosion of steel pipes starts and extends from this, thus losing the use value of powder coating. Pinholes can be detected by a pinhole detector (0-10000V). No sparks indicate no pinholes; ② The coating thickness is uniform and there is no seam. Using a computer thickness gauge, the thickness fluctuation is required to be small, and the normal coating thickness is within 0.5-3mm; ③ The adhesion is greater than 3kgf / cm, 10mm wide, 180° peeling, and the adhesion is required to be 5-10kgf / cm. Commonly used powder coatings for spiral steel pipe anti-corrosion coatings include polyethylene powder, epoxy resin powder, etc.

[0003] The coating of powder layer seems simple, but the technology to produce uniform thickness over a large area and precisely control the thickness and the equipment to implement this technology are not mature and have not been reported. The characteristics of powder are poor fluidity and cannot flow smoothly under the action of gravity or pressure; powder cannot transmit pressure, local pressure leads to local compression, which will block the flow channel and cause uneven mass density of the powder layer; powder, especially submicron powder, is easy to agglomerate, and special means must be used to make the thickness of such a powder layer uniform.

[0004] Powder particles are usually spread by rotating roller grooves, such as a powder spreading device of NIKKA (JP2012228639A, 20121122), in which a spreading roller 22 is provided at the lower outlet of the powder retention tank 20, and a plurality of recesses 23 are provided along the periphery of the spreading roller 22. The spreading roller 22 rotates at a certain speed, and the powder in the recesses 23 is continuously scattered. The recesses 23 are separated by grooves, and the interval of the grooves has the defect of uneven powder falling. The spreading roller 22 must be rotated at a relatively high speed of 500-1000 rpm / s to ensure the continuity of the powder. In this way, a relatively large-power motor must be used to drive the spreading roller 22 to rotate, which is relatively energy-consuming, and the coating amount is also difficult to accurately control.

[0005] The industry urgently needs to develop a powder coating uniform spreading shaft with uniform coating and variable coating amount. Summary of the invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a coating powder uniform spreading shaft with variable coating amount.

[0007] The present invention is implemented as follows: a coating powder uniform spreading shaft with variable coating amount, the spreading shaft is installed above the powder outlet of the hopper and can make the collected coating powder evenly fall from the spreading shaft to the surface of a rotating large-diameter steel pipe, including a screw body, the surface of the screw body is provided with a screw ridge with a fixed pitch and helical angle; a plurality of sleeves with different thicknesses, the sleeves include a sleeve body and a flange portion coaxially connected to the connecting end of the sleeve body, the sleeve body is provided with a spiral through groove with the same pitch and helical angle as the screw ridge and penetrating the wall thickness of the sleeve body, and the spiral through groove spirally extends out of the free end of the sleeve body;

[0008] The sleeve extends into the spiral groove through the spiral ridge and is spirally fitted outside the screw body, so that the empty part of the spiral groove becomes a powder filling groove;

[0009] The variable coating amount can be achieved by selecting sleeves with different thicknesses to cooperate with screw ribs to obtain different depths of powder filling the slots.

[0010] Furthermore, the wall thickness bn of the sleeve satisfies the arithmetic progression: b n =b 1 +(n-1)d, n is a positive integer greater than or equal to 2, d is the tolerance of the arithmetic progression; or there are 6 sleeves, the wall thickness of the 6 sleeves 20 is b n Satisfies the Fibonacci sequence: 1mm, 2mm, 3mm, 5mm, 8mm, 13mm, n=1, 2, 3, 4, 5, 6.

[0011] Furthermore, the sleeve body is also provided with a spiral groove, which has the same pitch and helix angle as the spiral through groove, and is arranged on the outer cylindrical surface of the sleeve body with a difference of half a pitch relative to the spiral through groove.

[0012] Furthermore, both ends of the screw body are rotatably arranged on the bearing seat, the sleeve body also includes a flange part coaxially connected to one end thereof, an end face bearing is arranged inside the flange part, the screw body includes a top shoulder, the screw ridge is screwed into the spiral groove until the free end of the sleeve body hits the top shoulder, and the end face bearing is rotatably supported on the bearing seat.

[0013] Furthermore, the depth of the spiral groove is the same as the depth of the powder filling groove.

[0014] Furthermore, the screw body also includes a cooling mechanism, which includes a water cooling channel and a return water pipe arranged in the screw body. The return water pipe is fixed in the water cooling channel and connected to the water cooling channel through a water hole. One end of the screw body is connected to a rotary joint, and the rotary joint is provided with a water inlet and a water outlet. The water inlet is connected to the water cooling channel, and the water outlet is connected to the return water pipe.

[0015] Furthermore, the sleeve and the screw body are respectively provided with pin holes, and positioning pins are arranged in the pin holes.

[0016] Furthermore, the surfaces of the plurality of sleeves directly indicate the depth of the powder filling groove obtained after the sleeve body and the screw ribs are rotated and matched.

[0017] Furthermore, the spiral through groove comprises a spiral matching groove and a spiral filling groove which are connected up and down, and the spiral filling groove has an inverted trapezoidal cross section which is small inside and large outside.

[0018] Furthermore, a reinforcing rib is provided at the free end of the sleeve body.

[0019] The powder coating uniform spreading shaft with variable coating amount cooperates with the screw ribs to form different depths of powder filling slots, thereby achieving adjustable coating amount. Simple means can ensure that, under the premise of unchanged rotation speed and forward speed of the steel pipe, the steel pipe coating can achieve production requirements of different coating thicknesses. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a main cross-sectional view of a first embodiment of a flow coating powder uniform spreading shaft with variable flow coating amount according to the present invention.

[0021] Figure 2 The invention discloses a flow coating powder uniform spreading shaft with variable flow coating amount. Figure 1 A partial enlarged view of I.

[0022] Figure 3 It is a main cross-sectional view of a second embodiment of a flow coating powder uniform spreading shaft with variable flow coating amount according to the present invention.

[0023] Figure 4 The invention discloses a flow coating powder uniform spreading shaft with variable flow coating amount. Figure 3 Partial enlarged view II.

[0024] Reference numerals in the above figures:

[0025] 1. Powder coating

[0026] 10 screw body, 11 screw ridge, 12 top shoulder, 13 bearing seat, 14 pin hole, 15 positioning pin

[0027] 20 sleeve, 21 sleeve body, 22 powder filling slot, 23 spiral through slot, 24 end bearing, 25 reinforcing rib, 26 spiral groove, 27 flange

[0028] 30 cooling mechanism, 31 water cooling channel, 32 water return pipe, 33 rotary joint, 34 water inlet, 35 water outlet, 36 water hole

[0029] 23.1 spiral groove, 23.2 spiral groove filling DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, but are not intended to limit the scope of the present invention.

[0031] Embodiment 1

[0032] like Figure 1 ,2 shows a coating powder uniformly spreading shaft with variable coating amount, the spreading shaft is installed above the powder outlet of the hopper and can make the collected coating powder 1 fall evenly from the spreading shaft to the surface of the rotating large-diameter steel pipe,

[0033] It comprises a screw body 10, wherein the surface of the screw body 10 is provided with a screw ridge 11 with a fixed pitch S, a helix angle α of 45° to 60°, a ridge width e3 to 10 mm, and a ridge height h0;

[0034] It also includes a plurality of sleeves 20 with different thicknesses, the sleeve 20 including a sleeve body 21, the sleeve body 21 is provided with a spiral groove 23 having the same pitch S and helix angle α as the screw rib 11 and penetrating the thickness of the sleeve body wall, the spiral groove 23 spirally extending out of the free end of the sleeve body; the sleeve 20 extends into the spiral groove 23 through the screw rib 11 and is spirally fitted outside the screw body 10, so that the empty part of the spiral groove becomes a powder filling groove 22, the depth h1 of the powder filling groove 22 is: h1=b-h0, b is the sleeve wall thickness, h0 is the screw rib height, and the variable coating amount is realized by selecting sleeves of different thicknesses to cooperate with the screw rib to obtain different depths of the powder filling groove 22. The surfaces of the plurality of sleeves 21 directly indicate the depth of the powder filling groove 22 obtained after the sleeve body and the screw rib are rotated and matched. The pitch of the powder filling groove 22 is preferably 30-50mm, the groove depth is preferably 2-5mm, and the width is preferably 2-3mm.

[0035] More preferably, the wall thickness bn of the sleeve 20 satisfies the arithmetic progression: bn=b1+(n-1)d, n is a positive integer greater than or equal to 2, d is the tolerance of the arithmetic progression, which means: the wall thickness of the next sleeve is dmm thicker than the wall thickness of the previous sleeve, and d can be 1, 2, or 3mm; or, if there are 6 sleeves, the wall thickness bn of the 6 sleeves 20 satisfies the Fibonacci sequence: 1mm, 2mm, 3mm, 5mm, 8mm, 13mm. This also means that the depth h1 of the powder filling slot 22 satisfies the arithmetic progression or Fibonacci sequence, and the width of the powder filling slot 22 is constant, then the volume Vpowder of the powder filling slot 22 satisfies the arithmetic progression or Fibonacci sequence.

[0036] The screw body 10 includes a top shoulder 12, and the screw ridge 11 is screwed into the spiral groove 23 of the sleeve body 21 until the end of the sleeve body 21 hits the top shoulder 12. After the sleeve and the screw body are assembled, a pin hole 14 is drilled, and a positioning pin 15 is arranged in the pin hole 14 to limit the relative angular displacement of the sleeve and the screw body during rotation.

[0037] The sleeve body further includes a flange portion 27 coaxially connected to one end of the sleeve body. An end bearing 24 is disposed inside the flange portion 22 , and the end bearing 24 is rotatably supported on the bearing seat 13 .

[0038] Since the spiral groove 23 extends through the sleeve body 21, Figure 1 As shown in the right end, in order to increase the strength of the free end, a reinforcing rib 25 is provided at the free end of the sleeve body 21.

[0039] The screw body 10 includes a cooling mechanism 30, which includes a water cooling channel 31 and a return pipe 32 arranged in the screw body 10. The return pipe is fixed in the water cooling channel 31 and connected to the water cooling channel 31 through a water hole 36. One end of the screw body is connected to a rotary joint 33, and the rotary joint 33 is provided with a water inlet 34 and a water outlet 35. The water inlet 34 is connected to the water cooling channel 31, and the water outlet 35 is connected to the return pipe 32.

[0040] Embodiment 2

[0041] The spiral groove on the surface of the sleeve body is improved, and the design of the spiral through groove is also improved. Other structures not described are the same as those in the first embodiment.

[0042] like Figure 3 As shown, a coating powder uniform spreading shaft with variable coating amount is installed above the powder outlet of the hopper to make the collected coating powder 1 fall evenly from the spreading shaft to the surface of the rotating large-diameter steel pipe. The outer cylindrical surface of the sleeve body 20 is also provided with a spiral groove 26. The spiral groove 26 has the same pitch S and helix angle α as the spiral through groove 23. The spiral groove 26 differs from the spiral through groove 23 by half a pitch S. The depth of the spiral groove 26 is the same as the depth of the powder filling slot 22.

[0043] Such a design is mainly because, when only the powder of the spiral groove is filled in the groove 22, within one cycle, the diameter located in the horizontal plane takes the cross section, and the screw body rotates one circle each time. When the groove of the front half pitch is located below the cross section, the groove of the front half pitch is in a powder sprinkling state, and the groove of the rear half pitch is located above the screw body 10. The groove of the rear half pitch is in a powder filling state, resulting in a flow-cutting and powder-shedding mode of each half pitch, which can be alleviated by increasing the screw body speed.

[0044] After adding the spiral groove 26 with a half pitch difference, the corresponding spiral groove of the first half pitch is just located above the cross section and is in a powder filling state, while the spiral groove of the second half pitch is located below the cross section and is in a powder spreading state, which just makes the powder spreading of the interrupted flow continuous in the axial direction. After adding the spiral groove 26 with a half pitch difference, the spiral grooves in the powder falling state at the same time are continuous in the axial direction.

[0045] The spiral through groove 23 comprises a spiral matching groove 23.1 and a spiral filling groove 23.2 which are connected up and down. The spiral filling groove 23.2 is an inverted trapezoidal cross section which is small inside and large outside, so as to facilitate the filling and scattering of powder particles.

[0046] Working principle:

[0047] This application solves the technical problem of "uniform coating and variable coating amount" through the following technical means:

[0048] (1) The spiral ridges of the screw body are matched with the spiral grooves of the sleeves of different thicknesses, so that the depth of the powder filling groove can be selectively changed

[0049] The spiral ridge 11 of the screw body 10 is rotated and fitted in the spiral groove 23 of the sleeve 20, so that the empty part of the spiral groove becomes the powder filling groove 22. The depth h1 of the powder filling groove 22 is: h1=b-h0, b is the sleeve wall thickness, and h0 is the spiral ridge height. For sleeves of different thicknesses, the depth of the spiral groove 23 corresponds to the thickness of the sleeve, so powder filling grooves 22 of different depths can be selectively obtained. For a groove with twice the depth, the corresponding coating amount is doubled at the same rotation speed. When the rotation speed and forward speed of the steel pipe remain unchanged, the coating thickness of the steel pipe will be doubled.

[0050] (2) The spiral groove and the powder filling slot are set half a pitch S apart, which cooperates to ensure that there is no gap in the coating.

[0051] The powder filling slot 22 with a pitch S and a helical angle α set on the sleeve, when it rotates, with the horizontal cross section of the diameter as the boundary, only the powder filling slot 22 with half a pitch located below the horizontal cross section is in a powder sprinkling state, and the powder filling slot 22 with the other half a pitch just turns to the top of the horizontal cross section in a powder filling state, that is, at any rotation moment, there are always half of the number of discontinuous half spirals in a filling state, and there are always half of the number of discontinuous half spirals in a powder sprinkling state. When a spiral groove 26 is set that is half a pitch forward or backward axially than the spiral groove, the corresponding half a pitch of the powder filling slot 22 just turned to the top of the horizontal cross section in a powder filling state is also in a powder sprinkling state. In this way, at any rotation moment, there are always multiple powder filling slots and spiral grooves arranged at intervals in the axial direction, which are in a powder sprinkling state in the axial direction, so that there is no gap in the spray coating. In this way, the speed of the roller can be greatly reduced, and a very low-power motor can be used. The speed of 30-50 revolutions per second can meet the requirements of continuous and uniform powder dropping, saving energy.

[0052] The powder coating uniform spreading shaft with variable coating amount realizes adjustable coating amount by ① forming different depths of powder filling slots through the cooperation of sleeves 20 with different thicknesses and spiral edges; ② achieving continuous axial powder dropping through the cooperation of spiral grooves and powder filling slots, which greatly reduces the rotation speed of the roller. The synergistic effect of the above two aspects realizes variable coating amount and uniform coating. Under the premise that the rotation speed and forward speed of the steel pipe remain unchanged, the steel pipe coating can achieve the production requirements of different coating thicknesses.

Claims

1. A coating powder uniform spreading shaft with variable coating amount, the spreading shaft being installed above the powder outlet of the hopper and enabling the collected coating powder (1) to fall uniformly from the spreading shaft onto the surface of a rotating large-diameter steel pipe, characterized in that: It comprises a screw body (10), wherein the surface of the screw body (10) is provided with a screw flight (11) with a fixed pitch (S) and a helical lead angle (α); A plurality of sleeves (20) of different thicknesses, the sleeves (20) comprising a sleeve body (21), the sleeve body (21) being provided with a spiral through groove (23) having the same pitch (S) and helix angle (α) as the screw fin (11) and penetrating the thickness of the sleeve body wall, the spiral through groove (23) spirally extending out of the free end of the sleeve body; The sleeve (20) extends into the spiral groove (23) through the screw ridge (11) and is spirally fitted outside the screw body (10), so that the empty part of the spiral groove becomes a powder filling groove (22); The sleeve (20) and the screw body (10) are respectively provided with a pin hole (14), and a positioning pin (15) is arranged in the pin hole (14); The variable coating amount is achieved by selecting sleeves of different thicknesses to cooperate with screw ribs to obtain different depths of powder filling the slot (22).

2. The powder coating uniform spreading shaft with variable coating amount as claimed in claim 1, characterized in that: The wall thickness b of the sleeve (20) n Satisfies the arithmetic progression: b n =b1+(n-1)d, n is a positive integer greater than or equal to 2, d is the tolerance of the arithmetic progression; or there are 6 sleeves, the wall thickness of the 6 sleeves (20) is b n Satisfies the Fibonacci sequence: 1mm, 2mm, 3mm, 5mm, 8mm, 13mm, n=1, 2, 3, 4, 5, 6.

3. The powder coating uniform spreading shaft with variable coating amount as claimed in claim 1, characterized in that: The sleeve body (21) is also provided with a spiral groove (26), the spiral groove (26) having the same pitch (S) and helix angle (α) as the spiral through groove (23), and the spiral groove (26) being arranged on the outer cylindrical surface of the sleeve body with a difference of half a pitch (S) relative to the spiral through groove (23), so that the spiral grooves in the powder falling state at the same time are continuous in the axial direction.

4. The powder coating uniform spreading shaft with variable coating amount as claimed in claim 3, characterized in that: The two ends of the screw body are rotatably arranged on the bearing seat (13), the sleeve body also includes a flange part (27) coaxially connected to one end thereof, an end face bearing (24) is arranged inside the flange part (27), the screw body (10) includes a top shoulder (12), the screw ridge (11) is screwed into the spiral groove (23) until the free end of the sleeve body (21) hits the top shoulder (12), and the end face bearing (24) is rotatably supported on the bearing seat (13).

5. The powder coating uniform spreading shaft with variable coating amount as claimed in claim 3, characterized in that: The depth of the spiral groove (26) is the same as the depth of the powder filling groove (22).

6. The powder coating uniform spreading shaft with variable coating amount as claimed in claim 3, characterized in that: The screw body (10) further comprises a cooling mechanism (30), wherein the cooling mechanism (30) comprises a water cooling channel (31) and a water return pipe (32) arranged in the screw body (10), wherein the water return pipe is fixed in the water cooling channel (31) and communicates with the water cooling channel (31) through a water hole (36), and one end of the screw body is connected to a rotary joint (33), wherein the rotary joint (33) is provided with a water inlet (34) and a water outlet (35), wherein the water inlet (34) is communicated with the water cooling channel (31), and the water outlet (35) is communicated with the water return pipe (32).

7. The powder coating uniform spreading shaft with variable coating amount as claimed in any one of claims 3 to 6, characterized in that: The surfaces of the plurality of sleeves (20) directly indicate the depth of the powder filling groove (22) obtained after the sleeve body and the screw rib are rotated and matched.

8. The powder coating uniform spreading shaft with variable coating amount as claimed in any one of claims 3 to 6, characterized in that: The spiral through groove (23) comprises a spiral matching groove (23.1) and a spiral filling groove (23.2) which are connected up and down, and the spiral filling groove (23.2) is an inverted trapezoidal cross section which is smaller inside and larger outside.

9. The powder coating uniform spreading shaft with variable coating amount as claimed in any one of claims 3 to 6, characterized in that: The free end of the sleeve body (21) is provided with a reinforcing rib (25).

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