CN103882362B - A kind of master mold for low-melting-point metal electric arc spraying mould is prepared and release method - Google Patents

Abstract

The invention discloses a master mold preparation and demoulding method for a low-melting point metal arc spraying mold, comprising: heating paraffin wax to a molten state, adding stearic acid or polyethylene, and chopped glass filaments to it, stirring evenly, Obtain modified paraffin wax; pour the modified paraffin wax into the size frame of the mold, remove the frame after curing, and obtain the modified paraffin wax master model; perform mechanical processing on the modified paraffin wax master model to obtain the required spraying surface; Roughen the surface of the modified paraffin wax master mold on the sprayed surface to obtain the mold master matrix; spray the mold master matrix, heat the sprayed mold master matrix to the molten state of the modified paraffin, and then pour it out to achieve Release between the master mold and the sprayed shell. The spraying master mold prepared by the invention has good machinability, convenient and simple manufacturing process, and can be quickly separated from the sprayed shell by heating without damaging the surface of the sprayed shell, saving demoulding time, Reduced the difficulty of demoulding.

Description

A method for preparing and demolding a master mold for low-melting-point metal arc spraying molds

【Technical field】

The invention relates to low-melting-point metal arc spraying rapid mold manufacturing technology, in particular to a master mold preparation and demoulding method for low-melting-point metal arc spraying molds.

【Background technique】

With the further integration of the global economy, the competition in the manufacturing industry has become increasingly fierce. How to shorten the production cycle and reduce costs has become the primary concern of manufacturers. The gradual advent of the era of multi-variety and small batches makes enterprises require mold manufacturing to ensure that new products can quickly occupy the market, and the development of fast and economical molds has attracted more and more attention. For example, epoxy, polyester or mixed with metal, ceramics, glass, etc. The rapid soft mold made of materials can be used for injection molding of hundreds of pieces and trial production of automobile panels. Its main features are simple manufacturing process, short production cycle and low price. However, due to the low thermal conductivity and mechanical properties of the material, this kind of mold is difficult to be used for high-frequency batch injection molding and batch forming of metal drawn parts. In recent years, a new technology for rapid manufacturing of molds has emerged. It is different from the simple molds mentioned in the past, but a brand new method. Rapid tooling manufacturing technology (Rapid Tooling, referred to as RT) refers to the use of rapid prototyping technology and corresponding follow-up processing to quickly make molds. Rapid tooling manufacturing technology can generally be divided into two categories: direct rapid tooling technology and indirect rapid tooling technology. Arc spraying rapid die is a kind of indirect rapid die.

Thermal spraying technology (ThermalSprayingTechnology) was invented by Mr. M.U.Shoop in Switzerland in 1909 and is an important part of surface engineering. As a kind of thermal spraying method, arc spraying technology is to use two metal wires as consumable electrodes, use the arc generated by the short circuit of the ends of the two wires to melt the wires, and use compressed gas to melt the melted metal mist It is a process of turning into micro-droplets, accelerating them, and depositing them on the surface of the substrate at a high speed to form a coating. Compared with other thermal spraying methods, arc spraying technology has the advantages of flexible spraying process, high heat utilization rate, long life, high efficiency, convenient preparation of pseudo-alloy coating, and good safety. Its application is mainly reflected in long-term anticorrosion, maintenance and surface modification, rapid mold making and so on.

Metal arc spraying rapid molding technology is a molding technology based on "replication". It uses a physical model (or prototype) as a master model, and deposits a certain thickness of dense metal on the surface of the master model by means of arc spraying. Coating, ie mold shell. The mold shell accurately copies the shape of the prototype and obtains the required mold cavity. After completing post-processing processes such as reinforcement, demoulding, and polishing, the rapid manufacturing of the mold can be completed. From product drawings to product production, it includes mold structure design, manufacturing, testing, assembly, mold testing and other links. The specific process of the arc spraying rapid mold making process is as follows: obtain the mold structure diagram through the mold structure design, propose the mold surface diagram from the mold structure diagram, add the process supplementary surface and process structure according to the spraying process to obtain the style diagram, and prepare the matrix according to the style diagram Master mold and surface treatment, deposit a certain thickness of mold shell on the surface of the substrate by arc spraying method, the mold shell accurately replicates the shape of the substrate, add a frame structure on the back of the mold shell and fill the backing material, after the backing material is solidified, remove The master model and the mold surface are cleaned. After the post-processing, a simple and fast mold can be obtained. After assembling with the steel structure, the mold can be tested. Compared with the traditional steel mold manufacturing, the metal arc spraying mold making technology has the advantages of fast mold making speed, short production cycle, low manufacturing cost, etc., and also has a certain mold life. It has become an important way for new product development and small batch production .

Since the cavity size and geometric accuracy of the arc spraying rapid mold depend entirely on the master mold, the quality of the sprayed layer is also closely related to the master mold. Ideally, the spray mold will have the exact same shape and precision as the master mold, and the master mold will be easy to clean and remove, ideally recyclable and environmentally friendly. Therefore, master mold making has an important position and function in the arc spraying rapid mold making process, and is the premise and basis of mold making.

For low-melting point metal arc spraying molding technology, such as spraying aluminum, zinc, zinc-aluminum alloy, etc., there are many types of master mold materials that can be used. At present, there are mainly rapid prototype resin parts, gypsum materials and medium density boards, etc., but resin parts It is easy to deform and requires additional support and reinforcement. The process is more complicated and the cost is higher; the cost of gypsum materials and MDF is lower, and the final shape is obtained by cutting. However, gypsum is corrosive to machine tool metal, which seriously threatens the use of machine tools At the same time, due to the complex mold surface and the curing shrinkage of the sprayed shell, these three types of materials currently have the problem of difficult demoulding, and all of them are destructive demoulding, and the master mold material cannot be reused. It is time-consuming and labor-intensive to manually remove the master mold, and it is easy to damage the profile when the operation is improper. Therefore, research on the master mold preparation and demoulding method suitable for the rapid mold release of low melting point metal arc spraying is to improve the efficiency of metal arc spraying rapid mold making. Reducing costs and realizing environmental protection are problems that need to be solved urgently.

【Content of invention】

The object of the present invention is to provide a master mold preparation and demoulding method for low melting point metal arc spraying molds, which can realize convenient demoulding of low melting point metal arc spraying molds, and is environmentally friendly and recyclable.

In order to achieve the above object, the present invention adopts following technical scheme to realize:

A master mold preparation and demoulding method for low-melting-point metal arc spraying molds, comprising the following steps:

1) According to the mass percentage, stearic acid or polyethylene, not more than 2% chopped glass wool and the rest are medium temperature paraffin. Weigh stearic acid or polyethylene, chopped glass wool and medium temperature paraffin respectively, and set aside , wherein the length of the chopped glass strands is 3-5mm;

2) Heat the paraffin to a molten state, add stearic acid or polyethylene, and chopped glass filaments to it, and stir evenly to obtain modified paraffin;

3) Pour the modified paraffin wax configured in step 2) into the size frame of the mold, and remove the frame after curing to obtain a modified paraffin wax master mold, wherein the master mold blank has a machining allowance of no more than 10mm;

4) Mechanically process the modified paraffin wax master mold to obtain the required spraying surface;

5) Roughening the surface of the modified paraffin wax master mold with a sprayed surface to obtain the mold master matrix;

6) Carry out low-melting-point metal arc spraying on the base of the mold master, heat the base of the mold master after spraying to the molten state of modified paraffin and pour it out, so as to realize the demoulding between the master mold and the sprayed shell.

The further improvement of the present invention lies in that: the melting point of the mesophilic paraffin is greater than or equal to 70 degrees.

The further improvement of the present invention lies in: in step 2), stearic acid or polyethylene is heated and melted and then added to paraffin.

The further improvement of the present invention lies in: in step 3), the wooden frame is used to nail the mold size surrounding frame according to the required mold size, which is used to obtain the overall master mold blank.

The further improvement of the present invention lies in: in step 4), the modified paraffin wax master mold is cut to obtain the required spraying profile.

The further improvement of the present invention lies in: in step 5), the method for roughening the surface of the modified paraffin wax master mold includes using coarse emery cloth to polish the surface, or cutting the surface of the modified paraffin wax master mold.

The further improvement of the present invention lies in: in step 5), after roughening the surface of the modified paraffin wax master model, its surface roughness is Ra5-Ra15.

The further improvement of the present invention is: in step 6), the modified paraffin wax in the middle part of the matrix of the mold matrix is firstly destroyed and removed, and then the rest of the modified paraffin wax is heated to its molten state and poured out.

The further improvement of the present invention lies in: using hot water or a heating device to melt the modified paraffin.

The further improvement of the present invention is: after adding the backing to the sprayed shell, the base of the mold master mold after spraying is heated to the molten state of modified paraffin and then poured out to realize the demoulding between the master mold and the sprayed shell .

The present invention applies the modified paraffin wax material to the low-melting point metal arc spraying rapid molding process. Compared with the existing rapid prototypes, gypsum and medium density board and other master mold bases, the master mold base made by the present invention has the following characteristics: advantage:

1. The modified paraffin wax of the present invention can be repeatedly heated and solidified, reused, relatively low in cost, environmentally friendly and pollution-free;

2. It can be heated with boiling water to melt the modified paraffin and solidify at room temperature, with low production energy consumption, simple manufacturing process, convenient operation, and short manufacturing cycle;

3. The matrix of the mold base is easy to separate from the sprayed shell, which frees people from the time-consuming and laborious demoulding work, and does not damage the surface quality of the sprayed shell;

4. The raw materials of the present invention have a wide range of sources and are easy to obtain.

【Description of drawings】

Figures 1 to 4 are the metal arc spraying rapid mold making process, wherein, Figure 1 is the preparation of the master mold; Figure 2 is the preparation process of the metal sprayed shell; Figure 3 is the addition of a backing after the sprayed metal shell; 4 is to remove the master mold to form the final metal arc spraying mold.

Among them: 1 is the master mold, 2 is the spray gun, 3 is the metal spraying shell, 4 is the surrounding frame, and 5 is the backing.

【detailed description】

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

Referring to Fig. 1 to Fig. 4, it is the metal arc spraying rapid molding process flow, wherein, Fig. 1 is the preparation of the master mold 1, including the preparation and processing of the master mold blank and surface roughening; Fig. 2 is the preparation process of the metal spraying shell 3, Mainly use the spray gun 2 to spray the atomized metal onto the surface of the treated master mold 1 to form a metal sprayed shell 3; Figure 3 shows that a backing 5 is added after the sprayed metal shell to achieve the enhancement of its mechanical properties; FIG. 4 shows the removal of the master mold 1 to form the final metal arc spraying mold. In FIGS. 3 and 4, the serial number 4 represents the surrounding frame. The present invention is mainly aimed at the master mold preparation (as shown in FIG. 1 ) and the demoulding part of the master mold (as shown in FIG. 4 ) in the entire metal arc spraying molding process.

The present invention is a kind of mother mold preparation and demoulding method for low-melting point metal arc spraying mould, comprising the following steps:

1) According to the mass percentage, stearic acid or polyethylene, not more than 2% chopped glass wool and the rest are medium temperature paraffin. Weigh stearic acid or polyethylene, chopped glass wool and medium temperature paraffin respectively, and set aside , wherein the melting point of the medium-temperature paraffin is greater than or equal to 70 degrees, and the length of the chopped glass strands is 3 to 5 mm;

2) Heating the paraffin wax to a molten state, adding stearic acid or polyethylene, and chopped glass filaments to it, stirring evenly to obtain a modified paraffin wax, in which stearic acid or polyethylene is heated and melted and then added to the paraffin wax;

3) Pour the modified paraffin wax configured in step 2) into the size frame of the mold, remove the frame after curing, and obtain the modified paraffin wax master mold, wherein the master mold blank has a processing allowance not greater than 10mm, Use a wooden frame to nail the mold size frame according to the required mold size;

4) Cutting the modified paraffin wax master mold to obtain the required spraying surface;

5) Roughening the surface of the modified paraffin wax master mold with a sprayed surface to obtain the mold master matrix;

6) Carry out low-melting-point metal arc spraying on the base of the mold master. After adding a backing to the sprayed shell, heat the base of the mold master after spraying until the modified paraffin melts and pour it out to realize the master mold and spraying. The demoulding between the mold shells, wherein, the method for roughening the surface of the modified paraffin wax master mold includes using coarse emery cloth to polish the surface, or cutting the surface of the modified paraffin wax master mold, and after roughening the surface of the modified paraffin wax master mold , and its surface roughness is Ra5~Ra15.

In the above step 6), it is also possible to destroy and remove the modified paraffin wax in the middle part of the matrix of the mold master, and then pour out the rest of the modified paraffin wax after heating until it melts, wherein hot water can be used to melt the modified paraffin wax .

Example 1:

Make a stamping die master mold for a car cover part, the size is: 800mm×600mm×150mm.

Including the following steps:

1) Paraffin wax modification: use medium temperature paraffin wax 162 as the raw material, stearic acid and 3mm chopped glass fiber as the modified material, the mass percentage of each raw material is: 10% stearic acid, 3mm chopped glass fiber Glass fiber 1%, the rest is medium temperature paraffin 162;

2) Stir evenly: first heat the medium-temperature paraffin 162 to 90 degrees to melt it with a heating device, add molten stearic acid and chopped glass strands to it, stir evenly, observe that there are few bubbles and the distribution of glass strands is relatively uniform, and the modified product is obtained. paraffin;

3) Nail the frame: slightly enlarge the size of the required master mold to leave enough processing and spraying allowance, nail a frame of 820×620×155mm according to the size of the mold, and place a supporting bracket for lifting under the frame;

4) Pour the configured modified paraffin into the frame, and remove the frame after curing at room temperature;

5) Cutting the modified paraffin wax master mold to obtain the required spraying surface;

6) Use rough abrasive cloth or thick steel brush to roughen the surface of the master mold to obtain the surface roughness requirements suitable for spraying;

7) Obtain the mold base and send it to the spraying room for low melting point metal arc spraying;

8) Heighten the surroundings of the sprayed and backed master mold with steel plates, melt it with boiling water, pour it out and place it in a special container, store it after solidification, and melt it for use next time when a new master mold needs to be made.

Example 2:

Make the master mold of stamping die for the cover part of a certain car model, the size is: 1000mm×800mm×200mm.

Including the following steps:

1) Paraffin wax modification: Use medium temperature paraffin wax 162 as the raw material base material, polyethylene and 3mm chopped glass filament as the modified material, the mass percentage of each raw material used is: polyethylene 10%, chopped glass filament 3mm in length 1 %, the rest is medium temperature paraffin 162;

2) Stir evenly: first heat the medium-temperature paraffin 162 to 90 degrees to melt it with a heating device, add molten polyethylene and chopped glass strands to it, stir evenly, observe that there are few bubbles and the glass strands are evenly distributed, and the modified paraffin wax is obtained ;

3) Nail the frame: slightly enlarge the size of the required master mold so as to leave enough processing and spraying allowance, nail a frame of 1020×820×205mm according to the size of the mold, and place a supporting bracket for lifting under the frame;

4) Pour the configured modified paraffin into the frame, and remove the frame after curing at room temperature;

5) Cutting the modified paraffin wax master mold to obtain the required spraying surface;

7) Use rough abrasive cloth or thick steel brush to roughen the surface of the master mold to obtain the surface roughness requirements suitable for spraying;

8) Obtain the mold base and send it to the spraying room for low melting point metal arc spraying;

9) Heighten the surroundings of the master mold after spraying and backing with steel plates, place it in an oven, and when heated to 90 degrees, the modified paraffin is in a molten state, take it out from the oven and pour it into a special container. Store it after solidification, and then melt it for use when you need to make a new master mold next time.

To sum up, the principle of the present invention is to use the characteristics of low temperature when the atomized particles of low-melting-point metal spraying reach the base of the master mold, and use simple and fusible materials to achieve high-efficiency, labor-saving and rapid demoulding. The paraffin modified material used improves the strength of the paraffin and can withstand the spraying pressure and the pulling force caused by deformation during the spraying process, and during the spraying process, the surface can withstand the temperature of the sprayed particles, which can be done in the state of boiling water It can be melted and solidified at room temperature, and then recycled repeatedly, which has the characteristics of environmental protection and pollution-free. Therefore, the present invention is a breakthrough method to promote the application of low-melting point metal arc spraying fast molds, which takes into account high efficiency, economy and environmental protection, and ensures that the sprayed shell will not appear during the demolding process, which may be caused by improper operation. surface quality problems.

The above content is a further detailed description of the method of the present invention in conjunction with specific preferred embodiments. It cannot be determined that the specific embodiments of the method of the present invention are limited to this. Under the premise of the concept of the method, some simple deduction or replacement can also be made, which should be regarded as belonging to the method of the present invention, and the scope of patent protection is determined by the submitted claims.

Claims (8)

1. the master mold preparation for low-melting-point metal electric arc spraying mould and release method, it is characterised in that comprise the steps:

1) it is stearic acid or the polyethylene of 0.5～20% by mass percentage, is not more than the staple glass silk of 2% and all the other are for middle fire stons wax, weigh stearic acid or polyethylene, staple glass silk and middle fire stons wax respectively, standby, wherein, the length of staple glass silk is 3～5mm, and middle temperature melting point of paraffin wax is be more than or equal to 70 degree；

2) by heating paraffin to molten state, add stearic acid or polyethylene and staple glass silk to it, stir, obtain modified paraffin；

3) by step 2) in the modified paraffin that configured pour in die size peripheral frame, remove peripheral frame after cured, obtain modified paraffin master mold, wherein, master mold blank leaves the allowance being not more than 10mm；

4) modified paraffin master mold is carried out machining, obtain required spraying profile；

5) the modified paraffin master tool surface with spraying profile being carried out roughening treatment, obtain mould mother plate substrate, wherein, after modified paraffin master tool surface roughening treatment, its surface roughness is Ra5～Ra15；

6) mould mother plate substrate is carried out low-melting-point metal electric arc spraying, the mould mother plate substrate heating after having sprayed is poured out to modified paraffin molten condition, it is achieved the demoulding between master mold and spraying shell.

2. a kind of master mold for low-melting-point metal electric arc spraying mould according to claim 1 is prepared and release method, it is characterised in that: step 2) in, add in paraffin after stearic acid or polyethylene are added heat fusing.

3. a kind of master mold for low-melting-point metal electric arc spraying mould according to claim 1 is prepared and release method, it is characterised in that: step 3) in, follow closely molding jig size peripheral frame with wooden frame according to die needed size, it is in order to obtain overall master mold blank.

4. a kind of master mold for low-melting-point metal electric arc spraying mould according to claim 1 is prepared and release method, it is characterised in that: step 4) in, modified paraffin master mold is carried out machining, obtains required spraying profile.

5. a kind of master mold for low-melting-point metal electric arc spraying mould according to claim 1 is prepared and release method, it is characterized in that: step 5) in, include using coarse sand cloth polishing surface to the method for modified paraffin master tool surface roughening treatment, or adopt cutting modified paraffin master tool surface.

6. a kind of master mold for low-melting-point metal electric arc spraying mould according to claim 1 is prepared and release method; it is characterized in that: step 6) in; first the modified paraffin of the middle part of mould mother plate substrate is carried out destruction to root out, then the heating of all the other modified paraffins is poured out to its molten condition.

7. a kind of master mold for low-melting-point metal electric arc spraying mould according to claim 1 or 6 is prepared and release method, it is characterised in that: adopt hot water or heater to make modified paraffin melt.

8. a kind of master mold for low-melting-point metal electric arc spraying mould according to claim 1 is prepared and release method; it is characterized in that: step 6) in; after the spraying shell sprayed is added backing; mould mother plate substrate heating after having sprayed is poured out to modified paraffin molten condition, it is achieved the demoulding between master mold and spraying shell.