CN109732079B - Production process of non-welding heat exchanger - Google Patents
Production process of non-welding heat exchanger Download PDFInfo
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- CN109732079B CN109732079B CN201910085828.4A CN201910085828A CN109732079B CN 109732079 B CN109732079 B CN 109732079B CN 201910085828 A CN201910085828 A CN 201910085828A CN 109732079 B CN109732079 B CN 109732079B
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Abstract
The invention relates to the technical field of heat exchanger processing, and discloses a production process of a weldless heat exchanger.
Description
Technical Field
The invention relates to the technical field of heat exchanger processing, in particular to a production process of a non-welding heat exchanger.
Background
Copper heat exchanger is the spare part that is used for carrying out the cooling to equipment such as computer, server, at present, is provided with a large amount of fins or forms honeycomb structure in order to let copper heat exchanger's heat transfer effect better in the copper heat exchanger to improve the area of contact between coolant liquid and the copper heat exchanger, improve cooling efficiency.
At present, because the whole water cooling system needs to operate in a sealed mode, an internal component with a large surface area is processed in advance in a conventional method, and then a cover plate is added in a brazing mode to form the sealed system. The brazing process may have poor welding, which may cause that the sealing degree of the cover plate does not meet the requirement, and may cause cracks to the cover plate in the welding process, which easily causes leakage of the water cooling system, and once the leakage occurs, the leaked cooling liquid may cause a short circuit phenomenon to the internal circuit of the server or the computer, and burn out components, thereby causing destructive damage to electronic components inside the server.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a production process of a non-welding heat exchanger, which is used for forming a compact heat exchanger through powder injection molding and sintering, does not need welding and reduces the possibility of leakage of the heat exchanger.
In order to achieve the purpose, the invention provides the following technical scheme:
a production process of a weldless heat exchanger comprises the following steps:
s1, preparing feed, namely mixing the powder raw materials and the high polymer binder according to the weight ratio of 95-85%: 5-15% of the feed is prepared by mass percentage;
s2, manufacturing an inner core, and forming the inner core by adopting a high-molecular polymer raw material through injection molding;
s3, insert injection, namely fixing the inner core in a copper heat exchanger green body injection mould, and carrying out injection molding on the feed prepared in the S1 to form a copper heat exchanger green body with the inner core;
s4, removing the inner core, degreasing the green body, removing the inner core from the green body of the copper heat exchanger with the inner core, and removing the high molecular binder in the green body of the copper heat exchanger;
s5, degreasing and sintering, namely sintering the copper heat exchanger green body without the inner core and the polymer binder in the S4, and adopting hydrogen or argon as a protective atmosphere;
wherein the high molecular polymer selected for the inner core material is one or more of POM, PC, PMMA and HIPS;
the raw material powder is pure copper or copper alloy, and the high molecular binder comprises one or more of paraffin, polypropylene, peanut oil, microcrystalline wax, polyformaldehyde and dioctyl phthalate.
Through above-mentioned technical scheme, with the mode shaping of product through the injection to set up the inner core and let the convenient shaping of the inside structure of heat exchanger, simultaneously, the inner core adopts macromolecular material to make, and it gets rid of it through subsequent degreased method, thereby lets inside space shaping, at this moment, does not need the welded mode to process, thereby has solved the quality problems that the heat exchanger produced in the course of working.
The invention is further configured to: the inner core is made of PMMA or HIPS, in S4, the copper heat exchanger green body with the inner core is soaked by an organic solvent to remove the inner core, and then the binder in the copper heat exchanger green body with the inner core removed is removed.
Through the technical scheme, PMMA and HIPS can be dissolved through an organic solvent, so that the inner core is removed.
The invention is further configured to: the organic solvent is one or a mixture of two of a dichloromethane solvent and an n-heptane solvent; and in the process of removing the binder in the copper heat exchanger green body with the inner core removed, oxalic acid is adopted for catalytic removal.
Through the technical scheme, the dichloromethane solvent can dissolve PMMA, and the n-heptane solvent can dissolve HIPS, so that the inner core is removed, and then the binder in the green body is catalytically removed through oxalic acid.
The invention is further configured to: the inner core is formed by POM, and in S4, the inner core in the copper heat exchanger green body with the inner core is removed by oxalic acid catalytic decomposition.
The invention is further configured to: in S4, the binder is removed from the green copper heat exchanger having the core, and then the core is removed.
Through above-mentioned technical scheme, adopt the inner core of POM, it can be got rid of through the oxalic acid with the unburned bricks simultaneously, gets rid of other binders through high temperature.
The invention is further configured to: in S4, the green copper heat exchanger with the inner core is firstly removed from the binder by oxalic acid catalysis or organic solvent soaking, and then the inner core is removed.
The invention is further configured to: and (8) removing the inner core in S4 by adopting a high-temperature heating mode.
The invention is further configured to: the inner core is made of PC material.
Through above-mentioned technical scheme, carry out the desorption through the mode of catalysis to some caking agent in the unburned bricks earlier, then in carrying out the desorption to the inner core, at this moment, the inner core adopts the PC material, and it can be through the mode of high temperature heat degreasing, with the inner core desorption, other caking agents in the unburned bricks are got rid of simultaneously.
The invention is further configured to: in S5, heating to 200-600 ℃ at a heating rate of 1-5 ℃/min, preserving heat for 30-120min, heating to 1000-1050 ℃ at a heating rate of 5-10 ℃/min, and sintering at high temperature.
Through above-mentioned technical scheme, in S5, earlier rise to certain degree the temperature, keep warm, make it further take out the polymer material that the desorption is unclean, then heat, make the powder be in little melt state, and then can make it bond together, form stable structure.
The invention is further configured to: the inner core has through holes for forming fins or other honeycomb members.
Through adopting above-mentioned technical scheme, the through-hole can let the feed get into to can let it form fin or honeycomb.
In conclusion, the invention has the following beneficial effects:
(1) the problem of liquid leakage caused by welding defects of a traditional brazing type copper heat exchanger product is solved, and the whole brazing type copper heat exchanger is formed at one time without leakage risks;
(2) the internal high-surface-area structure is formed by a die, so that the machining time is reduced, and the production efficiency can be greatly improved;
(3) the whole structure of the product is formed by a die, and the material utilization rate can reach 100 percent.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings.
Example 1
A production process of a non-welding heat exchanger is mainly used for producing a copper heat exchanger and comprises the following steps:
s1, preparing feed, wherein the mass ratio is respectively 90%: 0.8%: : 0.2%: adding 9% of copper-chromium alloy powder, microcrystalline wax, dioctyl phthalate and polyformaldehyde into a mixer with a stirring rod, wherein the particle size of the copper-chromium alloy powder is D50-10 mu m, heating to 185 ℃, mixing for 2 hours, pouring out the mixture, cooling and crushing into granules;
s2, manufacturing an inner core, and performing injection molding on a high polymer raw material HIPS to form the inner core; the structure of the inner core is a reverse rubbing structure of the internal structure of the heat exchanger. Wherein, the inner core is provided with through holes for forming fins or other honeycomb-shaped components; the through holes allow the feed to enter, allowing it to form fins or a honeycomb structure.
S3, insert injection, namely fixing an inner core formed by HIPS injection molding in a copper heat exchanger green body injection mold, and performing injection molding on the feed prepared in S1 to form a copper heat exchanger green body with the inner core, wherein the injection temperature is 190 ℃ and the injection pressure is 120 MPa;
s4, removing the inner core, degreasing the green body, putting the copper heat exchanger green body with the inner core into a dichloromethane solvent, soaking for 40 hours at the temperature of 35 ℃, and removing the HIPS inner core; the green copper heat exchanger blank with the inner core removed is degreased in an oxalic acid catalytic degreasing furnace for 6 hours, the conveying capacity of oxalic acid is 4 g/min, and the degreasing temperature is 130 ℃.
And S5, degreasing and sintering, namely placing the copper heat exchanger green body without the inner core and the polymer binder in the S4 in a vacuum sintering furnace, introducing argon atmosphere, introducing 10L/min of argon flow, heating to 600 ℃ (first-stage temperature) at a speed of 1 ℃/min (first-stage heating speed), preserving heat for 30 minutes, removing residual polymer materials in the green body, heating to 1050 ℃ (second-stage temperature) at a speed of 5 ℃/min (second-stage heating speed), and preserving heat for 2 hours.
After sintering in S5, a finished heat exchanger was formed and had a sintered density of 8.7g/cm3, with no leakage at 0.6MPa pressure.
The feed ratio in example 1 can also be adjusted according to the following table:
| copper-chromium alloy powder | Microcrystalline wax | Dioctyl phthalate | Polyoxymethylene | |
| 1 | 85％ | 3.2％ | 0.8％ | 11％ |
| 2 | 87％ | 2.5％ | 0.5％ | 10％ |
| 3 | 92％ | 1.6％ | 0.4％ | 6％ |
| 4 | 95％ | 0.4％ | 0.2％ | 4.4％ |
After being adjusted by the above feeding data, the corresponding adjustment is made to the process parameters in S5, as shown in the following table:
| one-stage temperature rising speedDegree of rotation | First stage temperature | Time of heat preservation | Two-stage rate of temperature rise | Two stage temperature | |
| 1 | 2℃/min | 500℃ | 35min | 6℃/min | 1000℃ |
| 2 | 3℃/min | 400℃ | 50min | 8℃/min | 1025℃ |
| 3 | 4℃/min | 300℃ | 80min | 9℃/min | 1025℃ |
| 4 | 5℃/min | 200℃ | 120min | 10℃/min | 1050℃ |
And (5) finally forming.
The following table was obtained on the test:
| sintered Density (g/cm3) | Whether or not the pressure can bear 0.6MPa of pressure | |
| 1 | 8.69 | Without leakage |
| 2 | 8.81 | Without leakage |
| 3 | 8.72 | Without leakage |
| 4 | 8.87 | Without leakage |
。
Example 2
A production process of a non-welding heat exchanger is mainly used for producing a copper heat exchanger and comprises the following steps:
s1, preparing feed, wherein the mass ratio is respectively 92%: 1%: 0.5%: 1.7%: adding 4.8% of pure copper powder, peanut oil, microcrystalline wax, polypropylene and paraffin into a mixer with a stirring rod, wherein the granularity of the pure copper powder is D50-12 mu m, heating to 165 ℃, mixing for 2 hours, pouring out the mixture, cooling and crushing into granules;
s2, manufacturing an inner core, and performing injection molding on a high polymer raw material PMMA to form the inner core;
s3, insert injection, namely fixing an inner core formed by PMMA injection molding in a copper heat exchanger green body injection mold, and carrying out injection molding on the feed prepared in S1 to form a copper heat exchanger green body with the inner core, wherein the injection temperature is 150 ℃ and the injection pressure is 100 MPa;
s4, removing the inner core, degreasing the green body, and soaking the green body of the copper heat exchanger with the inner core in a normal heptane solvent for 36 hours at the temperature of 50 ℃ to remove the PMMA inner core; and simultaneously removing the binders such as paraffin, peanut oil and the like in the green body;
and S5, degreasing and sintering, namely placing the copper heat exchanger green compact without the inner core and the polymer binder in the S4 into a continuous sintering furnace, introducing hydrogen gas atmosphere, wherein the hydrogen gas flow is 20L/min, the temperature of a high-temperature section of the sintering furnace is 1050 ℃, and the boat pushing speed is 8 minutes per boat.
After sintering in S5, a finished heat exchanger was formed and had a sintered density of 8.64g/cm3, with no leakage at 0.6MPa pressure.
The feed ratio in example 2 was also adjusted according to the following table, and the sintering temperature in S5 was also changed accordingly:
| pure copper powder | Peanut oil | Microcrystalline wax | Polypropylene | Paraffin wax | Sintering temperature in S5 | |
| 1 | 85％ | 2％ | 1.5％ | 2.5％ | 9％ | 1050℃ |
| 2 | 88％ | 1.5％ | 0.8％ | 1.7％ | 8％ | 1025℃ |
| 3 | 90％ | 1.2％ | 0.6 | 2.8％ | 5.4％ | 1000℃ |
| 4 | 95％ | 0.3％ | 0.2％ | 0.4％ | 4.1％ | 1025℃ |
And (5) finally forming.
The following table is obtained after testing the products formed by the above mixture ratio:
| sintered Density (g/cm3) | Whether or not the pressure can bear 0.6MPa of pressure | |
| 1 | 8.65 | Without leakage |
| 2 | 8.76 | Without leakage |
| 3 | 8.71 | Without leakage |
| 4 | 8.67 | Without leakage |
。
Example 3
A production process of a weldless heat exchanger is basically the same as that of the example 1, and production is carried out by adopting feed which is not adjusted in the example 1, and the difference is that in S2, the material for manufacturing the inner core is high molecular polymer raw material PC, and the inner core is formed by adopting PC injection molding.
In S4, firstly, degreasing a green body, then removing an inner core, firstly putting the green body of the copper heat exchanger with the inner core into an oxalic acid catalytic degreasing furnace for degreasing for 8 hours, wherein the conveying capacity of oxalic acid is 4 g/min, and the degreasing temperature is 130 ℃; and then putting the copper heat exchanger green body which is degreased by the green body and is provided with the inner core into a vacuum sintering furnace for thermal degreasing, introducing argon gas atmosphere with the flow rate of 10L/min, heating to 600 ℃ at the speed of 1 ℃/min, and preserving the heat for 10 hours.
And finally, performing S5, namely heating to 1050 ℃ at the speed of 5 ℃/min under the final state of S4, and keeping the temperature for 2 hours, wherein the argon flow is 10L/min and the temperature is 600 ℃.
After sintering in S5, a finished heat exchanger was formed and had a sintered density of 8.72g/cm3, with no leakage at 0.6MPa pressure.
Example 4
A production process of a weldless heat exchanger is basically the same as that of the embodiment 2, and the production is carried out by adopting the feed which is not adjusted in the embodiment 2, and the difference is that in S2, the material used for manufacturing the inner core is a high molecular polymer raw material POM, and the inner core is formed by POM injection molding.
In S4, firstly, soaking a copper heat exchanger green body with an inner core in a dichloromethane solvent for 24 hours at the temperature of 35 ℃, removing paraffin, peanut oil and the like in the green body, then putting the green body into an oxalic acid catalytic degreasing furnace for degreasing for 4 hours to remove the POM inner core, wherein the conveying capacity of oxalic acid is 4 g/min, and the degreasing temperature is 130 ℃;
and in the step S5, placing the copper heat exchanger green compact without the inner core and the polymer binder in the step S4 in a vacuum sintering furnace, introducing hydrogen gas atmosphere, wherein the hydrogen gas flow is 20L/min, the temperature of the high-temperature section of the sintering furnace is 1050 ℃, and the boat pushing speed is 8 minutes per boat.
After sintering in S5, a finished heat exchanger was formed and had a sintered density of 8.65g/cm3, with no leakage at 0.6MPa pressure.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
Claims (2)
1. A production process of a weldless heat exchanger is characterized by comprising the following steps:
s1, preparing feed, wherein the mass ratio is respectively 92%: 1%: 0.5%: 1.7%: adding 4.8% of pure copper powder, peanut oil, microcrystalline wax, polypropylene and paraffin into a mixer with a stirring rod, wherein the granularity of the pure copper powder is D50-12 mu m, heating to 165 ℃, mixing for 2 hours, pouring out the mixture, cooling and crushing into granules;
s2, manufacturing an inner core, and forming the inner core by using a high polymer material POM through injection molding;
s3, insert injection, namely fixing an inner core formed by POM injection molding in a copper heat exchanger green body injection mold, and carrying out injection molding on the feed prepared in S1 to form a copper heat exchanger green body with the inner core, wherein the injection temperature is 150 ℃ and the injection pressure is 100 MPa;
s4, firstly soaking the copper heat exchanger green body with the inner core in a dichloromethane solvent for 24 hours at the temperature of 35 ℃, removing paraffin and peanut oil in the green body, then putting the green body into an oxalic acid catalytic degreasing furnace for degreasing for 4 hours to remove the POM inner core, wherein the conveying capacity of oxalic acid is 4 g/min, and the degreasing temperature is 130 ℃;
and S5, placing the copper heat exchanger green compact without the inner core and the polymer binder in the S4 in a vacuum sintering furnace, introducing hydrogen gas atmosphere, wherein the hydrogen gas flow is 20L/min, the temperature of the high-temperature section of the sintering furnace is 1050 ℃, and the boat pushing speed is 8 minutes per boat.
2. The process for producing a weldless heat exchanger according to claim 1, wherein the inner core has through holes for forming fins or honeycomb members.
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