Pipe internal coating device
The innovative lance design with decreasing tube diameters and tip weight suppresses sagging and vibration, allowing smooth and efficient coating of small-diameter pipes without contact, addressing the efficiency issues of existing devices.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- KURIMOTO LTD
- Filing Date
- 2023-03-14
- Publication Date
- 2026-05-26
AI Technical Summary
Existing pipe inner surface coating devices cause contact scratches and reduce work efficiency due to the support roller contacting the inner surface of the pipe, especially in small-diameter pipes, limiting the painting process to one-directional movement.
A lance constructed by sequentially connecting tubes with decreasing outer diameters and using materials with lower specific gravity at the tip, minimizing sagging and eliminating the need for support rollers, while incorporating a weight at the tip to suppress vibration.
Enables smooth and efficient coating of the inner pipe surface without contact, reducing scratches and enhancing work efficiency by minimizing sagging and vibration.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to an inner surface coating device for pipes such as cast iron pipes, which is used when coating the inner surface of the pipes.
Background Art
[0002] Metal pipes such as cast iron pipes used for water distribution pipes for water supply are generally protected on their surfaces because deterioration such as corrosion progresses due to the influence of the external environment. For example, the inner surface of a cast iron pipe is subjected to powder coating with an epoxy resin powder coating or mortar lining with cement mortar, and corrosion resistance is imparted thereby.
[0003] The epoxy resin powder coating on the inner surface of a cast iron pipe is performed by inserting a coating lance longer than the pipe length into the pipe and injecting the powder coating from a nozzle provided at the tip of the lance. However, especially when constructing a pipe body with a small inner diameter (for example, an inner diameter of about 50 mm), the tip of the lance bent by its own weight may contact the inner surface of the pipe body, and the coating surface of the pipe body may be damaged. Therefore, for example, in the inner surface coating device according to Patent Document 1 below, a support roller 26 is provided on the tip side of the lance (paint pipe 21) to prevent the tip of the lance from directly contacting the inner surface of the coated pipe.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] In the painting process for pipes such as cast iron pipes, it is common practice to insert a lance that supplies paint into the pipe and then withdraw it, repeating this process about twice to apply multiple coats of paint. However, in the pipe internal coating apparatus described in Patent Document 1, the support roller 26 provided on the tip side of the lance comes into contact with the inner surface of the pipe. As a result, when painting while moving the lance in the direction of insertion into the pipe, contact scratches from the support roller 26 occur on the painted surface. Consequently, painting can only be done when moving the lance in the direction of withdrawal from the pipe, resulting in reduced work efficiency compared to painting in both directions.
[0006] Therefore, the object of this invention is to provide a pipe inner surface coating apparatus that can smoothly coat the inner surface of a pipe while avoiding contact between the tip of the lance and the inner surface of the pipe. [Means for solving the problem]
[0007] In order to solve the above problems, in this invention, A lance constructed by sequentially connecting multiple tubes whose outer diameter gradually decreases from the rear end to the front end, A nozzle provided at the tip of the lance, A pipe inner surface coating apparatus was constructed in which a material with a lower specific gravity is used for the pipe body at the front end compared to the pipe body at the rear end.
[0008] In this way, by gradually decreasing the outer diameter of the multiple tubes that make up the lance toward the tip, and by using a material with a low specific gravity for the tubes toward the tip, the amount of sagging at the tip can be minimized, eliminating the need to provide support rollers on the lance. As a result, it is possible to paint the inner surface of the tube smoothly while avoiding contact between the tip of the lance and the inner surface of the tube.
[0009] In the above configuration, the weight of each of the tubes constituting the lance can be configured to decrease sequentially from the rear end to the front end. This further suppresses the sagging of the front end of the lance.
[0010] In all of the above configurations, a weight is provided on the tube closest to the tip among the tubes constituting the lance, and the sum of the weight of the tube closest to the tip and the weight is smaller than the weight of the other tubes connected to the tube closest to the tip. By providing a weight in this way, when spraying powder paint from the nozzle provided at the tip of the lance, vibration of the lance tip due to the spray pressure can be suppressed, and the lance tip can be prevented from drooping due to the weight of the weight, thereby preventing the lance tip from contacting the inner surface of the tube.
[0011] In the configuration with the aforementioned weight, the weight can be positioned closer to the tip than the longitudinal center of the tube, which is closest to the tip. The tip of the lance is made small in diameter to prevent it from sagging and contacting the inner surface of the tube, but this small diameter can make the tip more susceptible to vibration. Thus, by providing a weight at the tip of the lance, vibration at the tip can be effectively suppressed. [Effects of the Invention]
[0012] In this invention, the lance of the pipe inner surface coating device is constructed by sequentially connecting multiple pipes whose outer diameter gradually decreases from the rear end to the front end, and by using a material with a lower specific gravity for the pipes at the front end compared to the pipes at the rear end. This minimizes the amount of sagging at the front end, allowing for smooth coating of the pipe inner surface while avoiding contact between the tip of the lance and the inner surface of the pipe. [Brief explanation of the drawing]
[0013] [Figure 1] Front view showing one embodiment of the pipe internal coating apparatus according to this invention. [Figure 2] Cross-sectional view of the pipe internal coating apparatus shown in Figure 1. [Figure 3] Enlarged cross-sectional view of the nozzle area of the pipe internal coating apparatus shown in Figure 1. [Figure 4] Enlarged cross-sectional view showing the state with a weight attached near the nozzle. [Figure 5] Front view showing a modified example of the pipe inner surface coating apparatus shown in FIG. 1
Mode for Carrying Out the Invention
[0014] An embodiment of the pipe inner surface coating apparatus 1 according to this invention will be described based on the drawings. This pipe inner surface coating apparatus 1 is an apparatus used when coating the inner surface of a pipe body such as a cast iron pipe (hereinafter referred to as a coated pipe). As shown in FIGS. 1 to 3, it has a main body portion 2, a lance 3 connected to the main body portion 2, and a nozzle 4 provided at the tip of the lance 3.
[0015] As shown in FIG. 2, the main body portion 2 is provided with a cooling pipe 5 through which a coolant for cooling the lance 3 flows, and a paint pipe 6 for sending paint to the tip of the lance 3. The tip of the cooling pipe 5 opens inside the lance 3 (inside the rear end pipe body 7c described later), and the coolant discharged from this opening refluxes to the main body portion 2 through the gap between the inner surface of the lance 3 and the cooling pipe 5 and the paint pipe 6. The paint pipe 6 extends to the tip of the lance 3.
[0016] The lance 3 is configured by sequentially connecting a plurality of pipe bodies 7 whose outer diameters gradually decrease from the rear end side to the front end side. In this embodiment, three pipe bodies 7 are connected. Hereinafter, these pipe bodies 7 will be referred to as a front end pipe body 7a, an intermediate pipe body 7b, and a rear end pipe body 7c in order from the front end side to the rear end side. The lance 3 according to this embodiment is assumed to be applied to the coating process of a coated pipe with an inner diameter of about 50 mm and a pipe length of about 4000 mm. The outer diameter of each pipe body 7 is about 27.6 mm for the rear end pipe body 7c, 21.6 mm for the intermediate pipe body 7b, and 16 mm for the front end pipe body 7a. Also, the length of the lance 3 connecting each pipe body 7 is designed to be longer than the pipe length of the coated pipe (for example, 4000 mm) so that the coating process can be performed smoothly.
[0017] As the material of the intermediate pipe body 7b and the rear end pipe body 7c, austenitic stainless steel pipe for pipe use (JIS G3459, SUS304TP, specific gravity 7.93 g / cm 3(hereinafter referred to as SUS) is used, and as the material of the tip tube body 7a, a titanium alloy (a pipe for two types of titanium for pipes (JISH4635, TTP340W), specific gravity 4.51 g / cm 3 (hereinafter referred to as titanium) is used.
[0018] The weight of each tube body 7 constituting the lance 3 decreases from the rear end side toward the front end side, that is, in the order of the rear end tube body 7c, the intermediate tube body 7b, and the front end tube body 7a. The weight of each tube body 7 adopted in this embodiment is 4.908 kg for the rear end tube body 7c, 1.743 kg for the intermediate tube body 7b, and 0.349 kg for the front end tube body 7a.
[0019] The nozzle 4 has a cylindrical portion 8 and a diffusion portion 9. The cylindrical portion 8 is provided at the tip of the tip tube body 7a. The diffusion portion 9 is a member for diffusing the paint sent from the paint tube 6 toward the entire inner circumference of the coated tube. As shown in FIG. 3, a conical member is adopted. The cylindrical portion 8 and the diffusion portion 9 are connected by a connecting member (not shown) designed to minimize the influence on the diffusion of the paint. The weight of the nozzle 4 adopted in this embodiment is 0.200 kg.
[0020] In this embodiment, an epoxy resin powder paint is adopted as the paint sent from the paint tube 6, but other types of paints can be adopted regardless of whether they are powders or liquids.
[0021] In the painting operation using this inner surface coating device 1 for pipes, first, the coated tube is heated to a temperature of about 300 ° C, and then a coolant is circulated through the cooling tube 5 of the inner surface coating device 1 for pipes. Then, while inserting the lance 3 of the inner surface coating device 1 into the inside of the coated tube, the epoxy resin powder paint supplied to the tip of the lance 3 through the paint tube 6 is ejected from the nozzle 4. The powder paint ejected from the nozzle 4 is sprayed onto the inner surface of the coated tube and cured on the inner surface to form an epoxy resin film. This inner surface coating device 1 for pipes prevents troubles such as the powder paint curing inside the lance 3 due to the heat from the coated tube by cooling the lance 3 with the coolant flowing through the cooling tube 5.
[0022] In the above embodiment, as shown in Figure 4, a weight 10 can also be provided near the nozzle 4 located on the tip tube 7a. The weight 10 is fixed to the tip tube 7a by a fixing ring and heat-resistant tape (neither of which are shown). The weight of the weight 10 used in this embodiment is 15g or 30g, and in either case, the sum of the weights of the tip tube 7a and the weight 10 is less than the weight of the intermediate tube 7b connected to the tip tube 7a. The mounting position of the weight 10 on the tip tube 7a is not particularly limited, but it is preferable to position it towards the tip rather than the longitudinal center of the tip tube 7a, and it is particularly preferable to position it adjacent to the nozzle 4, as shown in Figure 4.
[0023] By attaching a weight 10 to the tip tube 7a, the lance 3 can be reduced or prevented from shaking when powder paint is sprayed from the nozzle 4. The weight of the weight 10 can be adjusted as appropriate to minimize the amount of shaking of the lance 3 while preventing the tip of the lance 3 from drooping as much as possible.
[0024] In the above embodiment, the lance 3 was constructed by connecting three tubes 7 (tip tube 7a, middle tube 7b, and rear tube 7c). However, as shown in the modified example in Figure 5, it is also possible to construct the lance 3 by connecting two tubes 7 (tip tube 7a and rear tube 7c). In this case as well, the outer diameter of the tubes 7 decreases in stages from the rear end to the tip (in this modified example, the rear tube 7c is approximately 27.6 mm and the tip tube 7a is 16 mm), and the weight of each tube 7 decreases from the rear end to the tip, i.e., in the order of rear tube 7c and tip tube 7a. It is also possible to construct the lance 3 by connecting four or more tubes 7.
[0025] An evaluation test of the painting process using the pipe internal coating device 1 was conducted. The results are shown in Table 1. In this evaluation test, the lance's vibration, workability, and rust prevention were investigated when the material of the pipe body 7 (tip pipe body 7a, intermediate pipe body 7b, rear pipe body 7c) constituting the lance 3 was changed. The material used was titanium (titanium type 2 piping pipe (JIS H4635, TTP340W, specific gravity 4.51 g / cm³)). 3 )), SUS (Austenitic stainless steel pipe for piping (JIS G3459, SUS304TP, specific gravity 7.93 g / cm³) 3 )), and SS (carbon steel pipe for piping (JIS G3452, SGP, specific gravity 7.85 g / cm²). 3 There are three types: ))
[0026] Lance oscillation was evaluated by observing the oscillation of the tip of lance 3 when powder coating was sprayed from nozzle 4 located at the tip of lance 3. The symbols in Table 1 indicate the following: "◎: oscillation is very small and there is no contact with the inner surface of the pipe to be painted, ○: oscillation is small and there is no contact with the inner surface of the pipe to be painted, △: oscillation is large and there is a risk of contact with the inner surface of the pipe to be painted."
[0027] Workability was evaluated by the ease of adjusting the position (height) of the lance 3, which is constructed by connecting multiple tubes 7 (end tube 7a, middle tube 7b, and rear tube 7c), relative to the pipe to be painted. The symbols in Table 1 indicate the following: ○: Position adjustment of lance 3 is easy (requires little adjustment time), △: Position adjustment of lance 3 is somewhat difficult (requires adjustment time).
[0028] Rust prevention was evaluated by checking for corrosion of lance 3 due to the coolant (tap water in this case) flowing through cooling pipe 5. The symbols in Table 1 indicate the following: ○: No rust occurred, ×: Rust was observed.
[0029] Furthermore, the symbols in Table 1 related to the overall evaluation mean the following: ○: Can be applied to painting work without problems, △: May cause problems with painting work, ×: There is a high risk of problems with painting work.
[0030] [Table 1]
[0031] As shown in Examples 1 and 2, by using SUS for the intermediate tube 7b and the rear tube 7c, while using titanium for the tip tube 7a, good performance was achieved in terms of lance wobble, workability, and corrosion resistance, resulting in a high overall evaluation. In particular, as shown in Example 2, it was confirmed that the effect of suppressing lance wobble was further enhanced by providing a weight 10 on the tip tube 7a. Good suppression effects were observed whether the weight of the weight 10 was 15g or 30g.
[0032] On the other hand, as in Comparative Examples 1 and 2, when the tip pipe 7a, intermediate pipe 7b, and rear pipe 7c are all made of only one material selected from SUS or titanium, it became clear that adjusting the position of the lance 3 relative to the pipe to be painted was somewhat difficult, which could hinder the painting process. Furthermore, as in Comparative Example 3, when the tip pipe 7a, intermediate pipe 7b, and rear pipe 7c are all made of SS, in addition to the difficulty in adjusting the position of the lance 3 relative to the pipe to be painted, it was confirmed that rust occurred on the lance 3 due to the coolant, which was clearly likely to hinder the painting process.
[0033] Furthermore, as in Comparative Example 4, when the intermediate tube 7b and the rear tube 7c are made of SS material, while the tip tube 7a is made of titanium, although the ease of adjusting the position of the lance 3 relative to the painted pipe is improved, it was confirmed that rust occurs on the lance 3 due to the coolant, and it became clear that there is a high possibility that this will interfere with the painting work.
[0034] The above-described pipe inner surface coating apparatus 1 is constructed by sequentially connecting multiple pipe bodies 7, the outer diameter of which gradually decreases from the rear end to the front end, to form a lance 3. Furthermore, a material with a lower specific gravity is used for the pipe body 7 at the front end than for the pipe body 7 at the rear end. This minimizes the amount of sagging at the front end, allowing for smooth coating of the pipe inner surface while avoiding contact between the tip of the lance 3 and the inner surface of the pipe.
[0035] Furthermore, the above-described pipe inner surface coating apparatus 1 reduces the weight of each pipe body 7 constituting the lance 3 from the rear end to the front end, that is, in the order of rear pipe body 7c, intermediate pipe body 7b, and front pipe body 7a, thereby further suppressing the sagging of the front end of the lance 3.
[0036] Furthermore, since the above-described pipe internal coating apparatus 1 uses corrosion-resistant stainless steel and titanium as the material for the lance 3, rust can be prevented from occurring on the lance 3 by flowing a coolant through it.
[0037] Furthermore, the above-described pipe internal coating apparatus 1 is configured such that a weight 10 is provided at the tip of the lance 3 (tip pipe body 7a), and the sum of the weights of the tip pipe body 7a and the weight 10 is smaller than the weight of the intermediate pipe body 7b. Therefore, when spraying powder coating from the nozzle 4 provided at the tip of the lance 3, vibration of the tip of the lance 3 due to the spray pressure is suppressed, and the weight of the weight 10 prevents the tip of the lance 3 from drooping, thus preventing the tip of the lance 3 from contacting the inner surface of the pipe. For the vibration suppression effect of the lance 3, it is preferable that the weight 10 is provided closer to the tip than the longitudinal center of the tip pipe body 7a, and it is particularly preferable that it be located adjacent to the nozzle 4.
[0038] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Accordingly, the scope of the invention is indicated by the claims rather than by the foregoing description and is intended to include the meaning of equivalents of the claims and all modifications thereof. [Explanation of Symbols]
[0039] 1. Pipe internal coating device 2 Main body 3 Lance 4 nozzles 5 Cooling pipe 6 paint tube 7. Body 7a End tube 7b Intermediate tube 7c Rear end tube body 8 Cylinder part 9 Diffusion section 10 weights
Claims
1. A lance (3) is constructed by sequentially connecting multiple tubes (7) whose outer diameter gradually decreases from the rear end towards the front end, A nozzle (4) is provided at the tip of the lance (3), The tube body (7) at the front end has a lower specific gravity than the tube body (7) at the rear end. A pipe inner surface coating apparatus wherein, among the pipe bodies (7) constituting the lance (3), a weight (10) is provided on the pipe body (7) closest to the tip, and the sum of the weights of the pipe body (7) closest to the tip and the weight (10) is smaller than the weight of the other pipe bodies (7) connected to the pipe body (7) closest to the tip.
2. The pipe surface coating apparatus according to claim 1, wherein the weight of each pipe body (7) constituting the lance (3) is sequentially reduced from the rear end to the front end.
3. The pipe inner surface coating apparatus according to claim 1 or 2, wherein the weight (10) is provided on the tip side of the pipe body (7) that is closest to the tip, rather than the longitudinal center.