A tee pipe powder filling processing technology

Abstract

The application discloses a kind of tee pipeline powder filling processing technology, including the following percentage of raw material composition: modified calcium carbonate 70~85%, polypropylene resin 10~25%, toughening agent 1.5~3.5%, coupling agent 1~2%, foaming agent 0.3~0.8%, antioxidant 0.3~0.7%, lubricant 0.3~0.7%;The processing technology includes the following steps: S1, tube blank straightening cutting;S2, composite powder medium preparation and filling;S3, multi-stage cold extrusion forming;S4, extension section sawing;S5, filling medium removal;S6, post-processing.By using modified calcium carbonate, polypropylene resin as main raw material, and the proportion of auxiliary reagent such as toughening agent, coupling agent, effectively improve the support force and fracture resistance of composite filling powder to tee pipeline;By using subsection gradient pressurization, mold partition temperature control combination integrated process, the corresponding mold area of tee pipe main pipe, branch pipe, connecting extension section is differentially pressurized and temperature controlled.

Description

Technical Field

[0001] This invention relates to the field of tee fittings technology, and in particular to a powder filling process for tee pipes. Background Technology

[0002] Tee pipes, as important connecting components in piping systems, are widely used in construction, industry, water conservancy, and other fields, primarily for branching and merging pipelines. Currently, the main forming and processing methods for tee pipes are cold extrusion and hot extrusion, with cold pressurization being the primary method due to its lower cost and higher efficiency. Cold extrusion processes for tee pipes mainly include lead-filled extrusion, water-filled extrusion, and powder-medium-filled extrusion. However, lead-filled extrusion poses serious environmental and safety hazards. Lead, as a harmful heavy metal, leaves residues during filling, extrusion, and removal, thus polluting the air and causing acute or chronic toxicity to humans.

[0003] Furthermore, existing lead-alternative powder filling media suffer from poor molding precision and stability. Some use improperly proportioned powder media with poor flowability and filling density, leading to voids and looseness during filling. This results in uneven stress on the pipe during cold extrusion, causing molding defects such as uneven wall thickness and rough surface. Simultaneously, the powder media has poor compatibility with the inner wall of the tube blank, easily causing powder accumulation and tube blank breakage during extrusion. Therefore, a powder filling processing technology for tee pipes has been invented to address the shortcomings in the filling media proportioning and processing of tee pipes. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a powder filling process for tee pipes.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A powder-filled processing technology for tee pipes includes the following raw material composition in percentage: 70%–85% modified calcium carbonate, 10%–25% polypropylene resin, 1.5%–3.5% toughening agent, 1%–2% coupling agent, 0.3%–0.8% foaming agent, 0.3%–0.7% antioxidant, and 0.3%–0.7% lubricant;

[0007] The processing technology includes the following steps:

[0008] S1. Tube blank straightening and cutting: The original tube blank is straightened by a straightening machine, then cut into blanks of a specified length, and the cut end face is deburred.

[0009] S2. Preparation and filling of composite powder media:

[0010] a. Pretreatment: Calcium carbonate powder is added to a high-speed mixer and heated to dry. Then, coupling agent diluted with anhydrous ethanol is uniformly added to calcium carbonate in the form of spray and stirred at high speed. After discharge, the material is sieved to obtain modified calcium carbonate.

[0011] b. Preparation of composite powder media: Modified calcium carbonate and polypropylene resin are premixed in a high-speed mixer, and toughening agent, foaming agent, antioxidant and lubricant are added in sequence and mixed evenly;

[0012] c. Blank filling: The uniformly mixed composite powder medium is quantitatively filled into the inner cavity of the straightened and cut blank;

[0013] S3. Multi-stage cold extrusion molding: The filled blank is placed in a special T-shaped or Y-shaped tee cold extrusion die, and an integrated process combining segmented gradient pressurization and die zone temperature control is adopted to form a T-shaped or Y-shaped tee fitting with connecting extension section.

[0014] S4. Extension section sawing: The extension section of the formed T-shaped or Y-shaped tee pipe is sawed off to form a T-shaped or Y-shaped tee pipe;

[0015] S5. Removal of filling medium: Remove the powder medium filling the T or Y type tee tube;

[0016] S6. Post-processing: The T or Y type tee pipe is ground, polished, cleaned and dried to obtain the finished product.

[0017] Preferably, in step S3, the segmented gradient pressurization includes a first-stage pre-extrusion, a second-stage main extrusion, and a third-stage pressure holding and shaping, and the mold zone temperature control includes mold cavity temperature control and die temperature control.

[0018] Preferably, the pressure of the first stage pre-extrusion is 8-12 MPa, and the duration is 30-40 s; the pressure of the second stage main extrusion is increased to 25-35 MPa, and the duration is 60-80 s; the pressure of the third stage holding and shaping is maintained at 20-25 MPa, and the duration is 20-30 s.

[0019] Preferably, the temperature control of the mold cavity is 25-35°C, and the temperature control of the concave mold is 35-45°C.

[0020] Preferably, the coupling agent includes one or more of calcium stearate, titanate, and aluminate.

[0021] Preferably, the toughening agent is a polyolefin elastomer, the foaming agent is sodium bicarbonate, the antioxidant is pentaerythritol ester, and the lubricant is paraffin wax.

[0022] Preferably, in step S2, the calcium carbonate powder is dried at 100-110°C for 10-15 minutes and then stirred at high speed for 20-30 minutes.

[0023] Preferably, in step S5, the T-shaped or Y-shaped tee is heated to 300-550°C to melt and flow out the filling medium.

[0024] Preferably, after the filling medium melts and flows out, the T-type or Y-type tee is annealed. The annealing process includes heating at 500-600°C and holding for 12-20 minutes, followed by cooling.

[0025] Preferably, the material of the original tube blank is aluminum.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] This invention uses modified calcium carbonate and polypropylene resin as the main raw materials, combined with toughening agents, coupling agents, and other auxiliary reagents, to effectively improve the compatibility between calcium carbonate and polypropylene resin, resulting in a tighter bond between the composite filler powder and effectively enhancing the supporting force and fracture resistance of the composite filler powder for the tee pipe. By employing an integrated process combining segmented gradient pressurization and mold zoned temperature control, differentiated pressurization and temperature control are applied to the mold areas corresponding to the main pipe, branch pipe, and connecting extension section of the tee pipe. This allows the filler in the blank to be evenly dispersed throughout the entire tee pipe, improving not only the molding accuracy and structural integrity of the tee fittings but also significantly enhancing their load-bearing capacity and fracture resistance. Attached Figure Description

[0028] Figure 1 This is a process flow diagram of the present invention;

[0029] Figure 2 This is a cross-sectional schematic diagram of the tee pipe of the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0031] like Figures 1-2 As shown, this embodiment discloses a powder filling process for a three-way pipe, comprising the following percentages of raw materials: 70%–85% modified calcium carbonate, 10%–25% polypropylene resin, 1.5%–3.5% toughening agent, 1%–2% coupling agent, 0.3%–0.8% foaming agent, 0.3%–0.7% antioxidant, and 0.3%–0.7% lubricant.

[0032] Modified calcium carbonate: As the main filler, its high hardness and high proportion can significantly improve the rigidity, hardness, heat resistance and structural density of the filling material in the T-shaped pipe cavity, so that the T-shaped pipe has strong support and is not easily deformed when subjected to external extrusion.

[0033] Meanwhile, calcium carbonate modified with coupling agent can better bond with polypropylene resin. When the tee pipe is subjected to external impact, the modified calcium carbonate can disperse stress, thereby avoiding local cracking caused by stress concentration. In addition, the modified calcium carbonate can reduce the agglomeration of the filler in the tee pipe cavity and improve its dispersibility and fluidity during melting.

[0034] Polypropylene resin: It has good formability and rigidity. After melting, it can tightly bind modified calcium carbonate and other additives. Furthermore, the molded polypropylene resin can encapsulate fillers, further enhancing the overall load-bearing capacity of the tee pipe.

[0035] Toughening agent: Polyolefin elastomers are used as toughening agents to prevent breakage. Specifically, the polyolefin elastomers can undergo a grafting reaction with polypropylene resin, thereby improving the impact strength of the filler and preventing breakage of the tee pipe.

[0036] Coupling agents include one or more of calcium stearate, titanate, and aluminate. In this invention, titanate is used as a coupling agent, which is mainly used to modify calcium carbonate.

[0037] The foaming agent is sodium bicarbonate, and the lubricant is paraffin wax. The use of foaming agent and lubricant is mainly to ensure that the filler has sufficient fluidity, thereby ensuring the integrity of the tee pipe forming.

[0038] The antioxidant used is pentaerythritol ester, which can protect the filler from oxidation and thus maintain its stability.

[0039] The processing technology for the filling material inside the tee pipe includes the following steps:

[0040] S1. Tube blank straightening and cutting: The original tube blank is straightened by a straightening machine, then cut into blanks of a specified length, and the cut end face is deburred.

[0041] S2. Preparation and filling of composite powder media:

[0042] a. Pretreatment: Add calcium carbonate powder to a high-speed mixer and heat and dry at 100-110℃ for 10-15 minutes, and stir at high speed for 20-30 minutes. Then, add the coupling agent diluted with anhydrous ethanol evenly to the calcium carbonate in the form of spray and stir at high speed. After discharge, sieve to obtain modified calcium carbonate.

[0043] b. Preparation of composite powder media: Modified calcium carbonate and polypropylene resin are premixed in a high-speed mixer, and toughening agent, foaming agent, antioxidant and lubricant are added in sequence and mixed evenly;

[0044] c. Blank filling: The uniformly mixed composite powder medium is quantitatively filled into the inner cavity of the straightened and cut blank.

[0045] S3. Multi-stage cold extrusion molding: The filled blank is placed in a dedicated T-shaped or Y-shaped tee cold extrusion die, and an integrated process combining segmented gradient pressurization and die zone temperature control is used to form a T-shaped or Y-shaped tee fitting with a connecting extension section. The segmented gradient pressurization process avoids uneven stress on the filler material caused by single-stage high-pressure extrusion through staged pressure control; the die zone temperature control ensures the flowability and stability of the powder filler during extrusion through differentiated temperature adjustment. Furthermore, the synergistic effect of segmented gradient pressurization and die zone temperature control ensures more complete filling and tighter adhesion to the inner wall of the fitting, while also providing support, preventing deformation, and preventing breakage of the tee fitting.

[0046] Specifically, the segmented gradient pressurization process includes a first-stage pre-extrusion, a second-stage main extrusion, and a third-stage pressure holding and shaping, gradually achieving uniform distribution and dense curing of the filler, wherein:

[0047] The pressure of the first stage of pre-extrusion is controlled at 8-12 MPa, and the duration is 30-40 seconds. In this stage, the pressure is applied slowly at a lower level to allow the powder filler in the billet to adhere smoothly and evenly to the inner wall of the tube blank, thereby avoiding the formation of air bubbles in the inner cavity filler caused by direct impact of high pressure.

[0048] In the second stage of main extrusion, the pressure gradient increases to 25–35 MPa and lasts for 60–80 seconds. Based on the pre-extrusion, the powder filler is fully penetrated into every gap of the billet by increasing the pressure gradient, especially at the corners and joints of T-shaped or Y-shaped tees, thereby ensuring that the filler is tightly adhered to the inner wall of the billet without gaps.

[0049] The pressure during the third stage of pressure holding and shaping is maintained at 20-25 MPa. This stable pressure is applied for 20-30 seconds, allowing the fully filled powder filler to solidify and further enhance the bonding strength between the powder filler and the blank, while also fixing the final shape of the filler.

[0050] The mold zone temperature control includes mold cavity temperature control and die temperature control. The mold cavity temperature is controlled at 25-35℃, and the die temperature is controlled at 35-45℃. Differentiated temperature control is applied to the mold areas corresponding to the main pipe, branch pipe, and connecting extension section of the tee pipe to avoid reduced fluidity and insufficient filling due to excessively low local temperature, and premature curing of the filler due to excessively high temperature.

[0051] In summary, the synergistic effect of segmented gradient pressurization and mold zoned temperature control process enables the filler in the billet to be evenly distributed throughout the entire tee pipe, providing support for the tee pipe and preventing deformation due to excessive stress, thereby achieving extremely high density and morphological consistency. Compared with traditional extrusion molding processes, this method not only improves the forming accuracy and structural integrity of the tee pipe fittings, but also significantly enhances the load-bearing capacity and fracture resistance of the fittings.

[0052] S4. Extension section sawing: The extension section of the formed T-shaped or Y-shaped tee pipe is sawed off to form a T-shaped or Y-shaped tee pipe;

[0053] S5. Removal of filling medium: Heat the T-type or Y-type tee to 300-550°C to melt and flow out the filling medium, removing the powder medium filling the T-type or Y-type tee; after the filling medium melts and flows out, the T-type or Y-type tee is annealed, the annealing process including: heating at 500-600°C and holding for 12-20 minutes, followed by cooling.

[0054] The cold-extruded T-shaped or Y-shaped tee tube is heated to 300-550℃ to melt the powder filler into a low-viscosity fluid and flow out, thereby completely removing the filling medium inside the tube; after the filling medium has completely melted and flowed out, the T-shaped or Y-shaped tee tube is annealed to eliminate the residual stress inside the blank after segmented gradient pressurization.

[0055] The annealing process specifically involves heating at 500–600°C and holding for 12–20 minutes, followed by cooling. This annealing process at 500–600°C for 12–20 minutes, combined with cooling, further solidifies the morphology of the tee pipe and prevents minor deformations caused by the loss of temporary support after the removal of the filling medium. This maintains the supporting effect provided by the powder filler during the molding stage.

[0056] S6. Post-processing: The T or Y type tee pipe is ground, polished, cleaned and dried to obtain the finished product.

[0057] Example 1:

[0058] S1. Tube blank straightening and cutting: The original tube blank is straightened by a straightening machine, then cut into blanks of a specified length, and the cut end face is deburred.

[0059] S2. Preparation and filling of composite powder media:

[0060] a. Pretreatment: Calcium carbonate powder is added to a high-speed mixer and heated to dry. Then, 1.7% coupling agent diluted with anhydrous ethanol is evenly added to the calcium carbonate in the form of spray and stirred at high speed. After discharge, the modified calcium carbonate is obtained by sieving.

[0061] b. Preparation of composite powder media: 70% modified calcium carbonate and 25% polypropylene resin are placed in a high-speed mixer for premixing, and 2.0% toughening agent, 0.3% foaming agent, 0.3% antioxidant and 0.7% lubricant are added in sequence and mixed evenly;

[0062] c. Blank filling: The uniformly mixed composite powder medium is quantitatively filled into the inner cavity of the straightened and cut blank;

[0063] S3. Multi-stage cold extrusion molding: The filled blank is placed in a special T-shaped or Y-shaped tee cold extrusion die, and an integrated process combining segmented gradient pressurization and die zone temperature control is adopted to form a T-shaped or Y-shaped tee fitting with connecting extension section.

[0064] S4. Extension section sawing: The extension section of the formed T-shaped or Y-shaped tee pipe is sawed off to form a T-shaped or Y-shaped tee pipe;

[0065] S5. Removal of filling medium: Remove the powder medium filling the T or Y type tee tube;

[0066] S6. Post-processing: The T or Y type tee pipe is ground, polished, cleaned and dried to obtain the finished product.

[0067] Example 2:

[0068] The only difference between this embodiment and Embodiment 1 is the composition content of the composite powder medium in step S2. In this embodiment, the modified calcium carbonate is 75%, polypropylene resin is 20%, toughening agent is 2.0%, coupling agent is 1.2%, foaming agent is 0.6%, antioxidant is 0.5%, and lubricant is 0.7%.

[0069] Example 3:

[0070] The only difference between this embodiment and Embodiment 1 is the composition content of the composite powder medium in step S2. In this embodiment, the modified calcium carbonate is 80%, polypropylene resin is 14.5%, toughening agent is 2.5%, coupling agent is 1.5%, foaming agent is 0.5%, antioxidant is 0.5%, and lubricant is 0.5%.

[0071] Example 4:

[0072] The only difference between this embodiment and Embodiment 1 is the composition content of the composite powder medium in step S2. In this embodiment, the modified calcium carbonate is 85%, polypropylene resin is 10%, toughening agent is 1.5%, coupling agent is 1.7%, foaming agent is 0.8%, antioxidant is 0.7%, and lubricant is 0.3%.

[0073] Comparative Example 1:

[0074] The difference between this comparative example and Example 1 is as follows: In step S2, the specific difference is as follows, while the remaining steps (S1, S3-S6) are the same as in Example 1:

[0075] S2. Preparation and filling of composite powder media:

[0076] a. Pretreatment: Calcium carbonate powder is directly added to a high-speed mixer and heated and dried without adding coupling agent. After discharge, the powder is sieved to obtain unmodified calcium carbonate.

[0077] b. Preparation of composite powder media: 70% unmodified calcium carbonate and 25% polypropylene resin were premixed in a high-speed mixer, and 2.0% toughening agent, 0.3% foaming agent, 0.3% antioxidant and 0.7% lubricant were added in sequence and mixed evenly (the component content is the same as in Example 1, except that the calcium carbonate is unmodified).

[0078] c. Blank filling: The uniformly mixed composite powder medium is quantitatively filled into the inner cavity of the straightened and cut blank.

[0079] The pressure resistance and fatigue resistance of the tee pipes prepared in Examples 1 to 4 and Comparative Example 1 were measured. The results are shown in Table 1.

[0080] Table 1. Test results of various properties of the tee pipe

[0081] Test Project Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Compressive strength (MPa) 20.0 21.2 19.8 19.9 18.5 Anti-fatigue cycles (in ten thousand times) 30.6 30.3 30.5 30.8 25.0

[0082] As shown in Table 1, the pressure resistance directly reflects the ability of the tee pipe to resist pressure damage. The pressure resistance of Examples 1 to 4 of this invention is significantly better than that of Comparative Example 1. The pressure resistance of the tee pipe prepared in Example 4 is 19.9 MPa, which is only slightly different from the pressure resistance of Examples 1 (20.0 MPa), 2 (21.2 MPa), and 3 (19.8 MPa), indicating that they are at the same performance level. This fully demonstrates that the composite filler powder formulation of Example 4 can provide stable and good structural support for the tee pipe, thereby effectively improving the pressure resistance of the tee pipe.

[0083] Regarding fatigue resistance, the fatigue resistance cycles of Examples 1 to 4 of this invention are all higher than those of Comparative Example 1. Example 4 achieves a fatigue resistance cycle of 308,000 cycles, which is not only significantly better than the comparative example but also the highest among all examples. This significant advantage indicates that the tee pipe prepared in Example 4 exhibits the most outstanding fracture resistance. Since tee pipes are subjected to repeated impacts and alternating stresses from media flow during actual use, insufficient fatigue resistance can easily lead to cracks or breakage. Therefore, the high fatigue resistance of Example 4 can effectively extend the service life of the tee pipe.

[0084] In summary, the raw material formulations used in Examples 1 to 4 are superior to those in Comparative Example 1 in terms of pressure resistance and fatigue resistance. This fully demonstrates that the composite filler powder prepared by the formulation used in Example 4 has strong support and anti-breakage ability for the tee pipe.

[0085] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the invention.

Claims

1. A powder filling process for a three-way pipe, characterized in that, The raw material composition includes the following percentages: modified calcium carbonate 70%–85%, polypropylene resin 10%–25%, toughening agent 1.5%–3.5%, coupling agent 1%–2%, foaming agent 0.3%–0.8%, antioxidant 0.3%–0.7%, and lubricant 0.3%–0.7%. The processing technology includes the following steps: S1. Tube blank straightening and cutting: The original tube blank is straightened by a straightening machine, then cut into blanks of a specified length, and the cut end face is deburred. S2. Preparation and filling of composite powder media: a. Pretreatment: Calcium carbonate powder is added to a high-speed mixer and heated to dry. Then, coupling agent diluted with anhydrous ethanol is uniformly added to calcium carbonate in the form of spray and stirred at high speed. After discharge, the material is sieved to obtain modified calcium carbonate. b. Preparation of composite powder media: Modified calcium carbonate and polypropylene resin are premixed in a high-speed mixer, and toughening agent, foaming agent, antioxidant and lubricant are added in sequence and mixed evenly; c. Blank filling: The uniformly mixed composite powder medium is quantitatively filled into the inner cavity of the straightened and cut blank; S3. Multi-stage cold extrusion molding: The filled blank is placed in a special T-shaped or Y-shaped tee cold extrusion die, and an integrated process combining segmented gradient pressurization and die zone temperature control is adopted to form a T-shaped or Y-shaped tee fitting with connecting extension section. S4. Extension section sawing: The extension section of the formed T-shaped or Y-shaped tee pipe is sawed off to form a T-shaped or Y-shaped tee pipe; S5. Removal of filling medium: Remove the powder medium filling the T or Y type tee tube; S6. Post-processing: The T or Y type tee pipe is ground, polished, cleaned and dried to obtain the finished product.

2. The powder filling process for a three-way pipe as described in claim 1, characterized in that, In step S3, the segmented gradient pressurization includes a first-stage pre-extrusion, a second-stage main extrusion, and a third-stage pressure holding and shaping, and the mold zone temperature control includes mold cavity temperature control and die temperature control.

3. The powder filling process for a three-way pipe as described in claim 2, characterized in that, The pressure of the first stage pre-extrusion is 8-12 MPa, and the duration is 30-40 s; the pressure of the second stage main extrusion is increased to 25-35 MPa, and the duration is 60-80 s; the pressure of the third stage holding and shaping is maintained at 20-25 MPa, and the duration is 20-30 s.

4. The powder filling process for a three-way pipe as described in claim 2, characterized in that, The temperature control of the mold cavity is 25-35℃, and the temperature control of the concave mold is 35-45℃.

5. The powder filling process for a three-way pipe as described in claim 1, characterized in that, The coupling agent includes one or more of calcium stearate, titanate, and aluminate.

6. The powder filling process for a three-way pipe as described in claim 1, characterized in that, The toughening agent is a polyolefin elastomer, the foaming agent is sodium bicarbonate, the antioxidant is pentaerythritol ester, and the lubricant is paraffin wax.

7. The powder filling process for a three-way pipe as described in claim 1, characterized in that, In step S2, the calcium carbonate powder is dried at 100-110°C for 10-15 minutes and then stirred at high speed for 20-30 minutes.

8. The powder filling process for a three-way pipe as described in claim 1, characterized in that, In step S5, the T-type or Y-type tee pipe is heated to 300-550°C to melt and flow out the filling medium.

9. The powder filling process for a three-way pipe as described in claim 8, characterized in that, After the filling medium melts and flows out, the T-type or Y-type tee pipe is annealed. The annealing process includes heating at 500-600°C and holding for 12-20 minutes, followed by cooling.

10. The powder filling process for a tee pipe as described in claim 1, characterized in that, The original tube blank is made of aluminum.

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