阅读说明：本技术 一种填充材料及填充方法 (Filling material and filling method ) 是由 万海华 吕仕强 王涛 于 2020-05-21 设计创作，主要内容包括：本发明公开了一种填充材料及填充方法,用于解决铝合金薄壁管类零件及整体叶轮薄壁叶片在车削过程中的加工变形及切削震动控制问题,进而达到最终零件尺寸及型面精度要求。本发明利用以尿素为基础的二元低共熔点填充材料将薄壁零件中的薄壁片与薄壁片连成一个整体,也将薄壁与填充材料形成类似一个实体,减少了加工过程薄壁的切削振动现象,同时减少了薄壁切削不均匀造成的零件变形,从而提高薄壁零件的加工精度。(The invention discloses a filling material and a filling method, which are used for solving the problems of processing deformation and cutting vibration control of aluminum alloy thin-wall pipe parts and integral impeller thin-wall blades in the turning process, and further achieving the requirements of final part size and molded surface precision. The invention utilizes the binary eutectic point filling material based on urea to connect the thin-wall sheet and the thin-wall sheet in the thin-wall part into a whole, and also forms the thin wall and the filling material into a similar entity, thereby reducing the cutting vibration phenomenon of the thin wall in the processing process, and simultaneously reducing the part deformation caused by uneven cutting of the thin wall, thereby improving the processing precision of the thin-wall part.)

1. A filling material, characterized by: the urea-water mixture is liquefied to fill the gap position in the thin-wall part, and then solidified to form a solid integral structure with the thin-wall part.

2. A filling material according to claim 1, wherein: the compound comprises ammonium phosphate, potassium chloride, sodium borate, sodium benzoate, propionamide and acetamide, and the filling material further comprises fibers which are dispersed in a solid integral structure, and the direction of the fibers is along the contour direction of the thin-wall structure of the thin-wall part.

3. A filling material according to claim 1, wherein: the thin-wall parts are impeller thin-wall blades and thin-wall pipe parts.

4. A filling method of the filling material according to claim 1, comprising the steps of:

the first step is as follows: selecting a flat plate with a smooth surface as a bottom plate for placing the part according to the outer diameter of the part to be processed, bending a thin plate to seal the thin plate along the outer periphery of the part and wrap the part, wherein the inner surface of the thin plate is attached to the part as far as possible;

the second step is that: laying a layer of solid urea between the bottom layer of the part to be processed and the flat plate, and placing scattered fibers in a closed area formed by the thin plate and near the thin-wall structure of the part to be processed;

the third step: pouring the liquefied eutectic point urea mixture into a closed area formed by the thin plates;

the fourth step: and after pouring, the eutectic point urea mixture is cooled and solidified and forms an integral solid blank together with the part to be processed.

5. The filling method of a filling material according to claim 4, characterized in that: in the second step, the fiber is plant fiber, including hemp, rice straw, leaves or cloth silk.

6. The filling method of a filling material according to claim 4, characterized in that: in the second step, kraft paper is laid between the solid urea laying layer and the upper surface of the flat plate.

7. The filling method of a filling material according to claim 4, characterized in that: and in the third step, the liquefied eutectic point urea mixture is poured for multiple times, and the thickness range of the liquefied eutectic point urea mixture poured each time is 3-20 mm.

8. The filling method of a filling material according to claim 7, characterized in that: when the liquefied eutectic point urea mixture is poured for multiple times, the next eutectic point urea mixture is poured when the surface layer of the liquefied eutectic point urea mixture poured for the last time is rapidly solidified, and the circulation operation is carried out.

9. The filling method of a filling material according to claim 7, characterized in that: when the liquefied eutectic point urea mixture is poured for multiple times, after the liquefied eutectic point urea mixture is poured once, a layer of solid urea is paved on the surface of the liquefied eutectic point urea mixture.

10. The filling method of a filling material according to claim 4, characterized in that: before the first step, the environmental temperature and humidity are controlled, wherein the pouring temperature is controlled at room temperature of 20 ℃, and the humidity is controlled at 20% -60%.

Technical Field

The invention relates to a method for controlling machining deformation and cutting vibration in the turning process of aluminum alloy thin-wall pipe parts and integral impeller thin-wall blades, in particular to a filling material for forming the aluminum alloy thin-wall pipe parts and the integral impeller thin-wall blades into approximate entities and a filling method of the filling material.

Background

At present, the design requirements of thin-wall pipe parts and impeller thin-wall blades cannot be met by the conventional processing scheme in the processing process. For example, the thickness of the thin wall of the impeller is: 0.2-3 mm, height of the blade: 50-100 mm, length arc length 150-200 mm, because the mechanical cutting process produces cutting vibrations, the part surface finish is poor and the excircle cutting warp, the part size is difficult to guarantee. The actual processing results are shown as: the maximum difference of the sizes of the parts is about 2mm, and the roughness is 3.2-6.4. Deviation from the design requirements results in batch scrap. Due to the situation, the product has a technological bottleneck in the implementation process, the product delivery cannot be completed, and the scientific research and production progress is seriously influenced.

Disclosure of Invention

In view of the above problems, the present invention is directed to a filling material and a filling method, which can fill material between thin-walled structures (thin-walled sheets) so that the filled material and the thin-walled structure form an approximate entity. The thin-wall part clamping deformation is avoided, the vibration of the thin-wall part in the machining process is reduced, the cutting stability is improved, the surface quality of the part is improved, and the size error of the thin wall is reduced.

The technical scheme adopted by the invention is as follows:

a filling material comprises urea and a compound which is easy to dissolve in water, wherein the urea and the compound are mixed to form a eutectic point urea mixture, the mixture is liquefied to be used for filling the gap position in a thin-wall part, and then is solidified to form a solid integral structure with the thin-wall part.

Further, the compound comprises ammonium phosphate, potassium chloride, sodium borate, sodium benzoate, propionamide and acetamide, and the filling material further comprises fibers, wherein the fibers are dispersed in a solid integral structure, and the direction of the fibers is along the contour direction of the thin-wall structure of the thin-wall part.

Preferably, the thin-wall parts are impeller thin-wall blades and thin-wall pipe parts.

The filling method of the filling material comprises the following steps:

the first step is as follows: selecting a flat plate with a smooth surface as a bottom plate for placing the part according to the outer diameter of the part to be processed, bending a thin plate to seal the thin plate along the outer periphery of the part and wrap the part, wherein the inner surface of the thin plate is attached to the part as far as possible;

the second step is that: laying a layer of solid urea between the bottom layer of the part to be processed and the flat plate, and placing scattered fibers in a closed area formed by the thin plate and near the thin-wall structure of the part to be processed;

the third step: pouring the liquefied eutectic point urea mixture into a closed area formed by the thin plates;

the fourth step: and after pouring, the eutectic point urea mixture is cooled and solidified and forms an integral solid blank together with the part to be processed.

Preferably, the blank formed in the fourth step is not processed for more than 24 hours, and the environmental humidity of the blank stored is controlled between 20% and 60%.

Preferably, in the second step, the fiber is plant fiber, including hemp, rice straw, leaves or cloth silk.

Preferably, kraft paper is laid between the solid urea laying layer and the upper surface of the flat plate in the second step.

Preferably, in the third step, the liquefied eutectic point urea mixture is poured for multiple times, and the thickness range of the liquefied eutectic point urea mixture poured for each time is 3-20 mm.

Alternatively, when the liquefied eutectic point urea mixture is poured for multiple times, the next eutectic point urea mixture (liquid) is poured when the surface layer of the liquefied (liquid) eutectic point urea mixture poured for the last time is rapidly solidified, and the operation is circulated.

Alternatively, when the liquefied (liquid) eutectic point urea mixture is poured in multiple times, a layer of solid urea is paved on the surface of the liquefied (liquid) eutectic point urea mixture every time the liquefied (liquid) eutectic point urea mixture is poured.

Preferably, before the first step, the environmental temperature and humidity are controlled, wherein the casting temperature is controlled at room temperature of 20 ℃ and the humidity is controlled at 20-60%.

The invention can be applied to aluminum alloy thin-wall pipe parts and integral impeller thin-wall blades, and meets the requirements of final part size and molded surface precision by controlling machining deformation and cutting vibration in the turning process.

The thin-wall sheet structure and the thin-wall sheet structure of the thin-wall part are connected into a whole by using the filling material, and the thin wall and the filling material form a similar entity, so that the cutting vibration phenomenon of the thin wall in the machining process is reduced, and the part deformation caused by uneven cutting of the thin wall is reduced, thereby improving the machining precision of the thin-wall part.

The invention takes urea as a base, selects a compound which can form eutectic point with the urea, so that the mixture of the urea and the compound can be melted into liquid at lower temperature (lower than the melting point of pure urea), and accords with the pouring condition. Furthermore, the binary mixture has wide enough melting point range and strength range according to different selected compounds and different mixing proportions, is suitable for thin-wall parts with different structures and shapes, and is convenient for processing personnel to adjust and select according to different part characteristics. And because the binary mixture is easy to dissolve in water, almost has no corrosivity and has little pollution, the mixture which is integrated with the part can be conveniently dissolved and removed by water at normal temperature after processing and forming, and adverse effects of high-temperature deformation, surface corrosion, environmental pollution and the like caused by high-temperature dissolution or heating dissolution or organic solvent dissolution are avoided.

Drawings

Fig. 1 is a schematic structural view of a fan wheel involved in the present invention;

fig. 2 is a schematic casting diagram of a fan wheel according to the present invention.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and specific embodiments, but it should not be understood that the scope of the subject matter of the present invention is limited to the following embodiments, and various modifications, substitutions and alterations made based on the common technical knowledge and conventional means in the art without departing from the technical idea of the present invention are included in the scope of the present invention.

As shown in fig. 1, the fan impeller needs to be cut, and in this embodiment, a filler is used to fill a gap region between the thin-wall blade and the thin-wall blade in the fan impeller structure, so as to form an integrated solid structure. The problems that the size deformation is out of tolerance and the product surface roughness is unqualified in the existing mechanical cutting process are solved.

Firstly, a filling material is selected, and the selected filling material has the following characteristics:

firstly, the expansion coefficient is small;

the filling material has good cutting performance;

the filling material has good bonding property and detachability;

fourthly, the melting point is low (the solid-state conversion of the material liquid is convenient);

fifthly, the composite material has good strength, rigidity and shock absorption.

According to the above 5-point requirements, the common filling materials are shown in the following table 1,

table 1: properties of the Filler Material

In view of the fact that ammonium phosphate, potassium chloride, sodium borate, sodium benzoate, propionamide and acetamide in the existing compounds are all easily soluble in water, and the melting point of the binary mixture formed by the ammonium phosphate, the potassium chloride, the sodium borate, the sodium benzoate, the propionamide and the acetamide is adjustable and lower than the melting point of pure urea, so that the mixture of the ammonium phosphate, the potassium chloride, the sodium borate, the sodium benzoate, the propionamide.

For example, when urea and potassium chloride are mixed according to the mass ratio of 1:3, the melting point of the mixture is about 112 ℃, and when urea and ammonium chloride are mixed according to the mass ratio of 3:17, the melting point of the mixture is about 101 ℃, so that an appropriate binary mixture can be selected according to the processing requirements of the thin-wall blades or thin-wall pipe parts of the aluminum alloy integral impeller, and the melting point of the mixture is ensured to be as low as possible, and meanwhile, the integral blank formed by the mixture and the parts is not influenced, and the integral blank has good processing strength.

In the embodiment, in consideration of the characteristics and the processing requirements of the thin-wall blade of the aluminum alloy integral impeller, a eutectic point urea mixture is formed by mixing urea and propionamide in equal mass (1:1), and the melting point of the eutectic point urea mixture is about 70 ℃. Wherein, the urea is in a granular type, the diameter of the granules is 1.18 mm-3.35 mm, the nitrogen content is not less than 46.3 percent, and the propionamide is a flaky solid.

In general, the filling of the eutectic mixture material is performed according to the following steps:

before casting, the casting environment needs to be controlled, the temperature and the humidity of the casting environment can influence the bonding rate and the compactness of the filling material, so that the casting temperature is controlled at room temperature (20 ℃) and the humidity is controlled between 20% and 60%, and then the following steps are carried out.

The first step is as follows: selecting a smooth flat plate according to a part to be processed, using a thin-wall steel sheet to enclose the part, fitting the part with a circle formed by the thin-wall steel sheet as far as possible, wherein the thickness of the selected steel sheet is 0.1-1 mm;

the second step is that: a layer of solid urea is laid on the bottom layer of the part, the height of the laid layer of solid urea can be selected according to the size of the part, usually 1-7 mm, and scattered fibers (plant fibers: hemp, rice straws, leaves or cloth yarns and the like) are placed in the part;

the third step: pouring the liquefied eutectic point urea mixture into the thin-wall steel sheet circle, wherein the thickness of the poured liquefied eutectic point urea mixture is selected according to the size of the part and is usually controlled to be 3-20 mm;

the fourth step: when the surface layer of the liquid eutectic point urea mixture is rapidly solidified (the solidification time is selected according to the thickness of the pouring liquid and is usually 3-20 min), continuing pouring, and repeatedly operating until the filling liquid is completely poured;

the fifth step: the time (T) for processing a blank formed by cooling and solidifying after the eutectic point urea mixture is poured is not more than 24h, namely: t is less than or equal to 24h, and the humidity (E) is controlled between 20% and 60%, namely: e is 20-60%.

According to the performance requirements of the filling materials listed in table 1, urea is finally selected as the filling material of the embodiment according to the process performance, the ease of operation of raw materials and the high and low cost; selecting a certain fan impeller as a part, wherein the basic parameters of the impeller are as follows: diameter of the impeller:height: 90mm, thickness of the blade: 0.7-1.3 mm, height of the blade: 33mm, arc length of blade 173mm, detail parts are shown with reference to fig. 1.

The specific impeller filling material operation steps are as follows:

drying impeller parts, including parameter adjustment of a drying oven: temperature: 20 ℃, humidity: 55% and the parameters are stabilized in the apparatus, then the impeller parts are placed in the drying cabinet and the parts are kept in the drying cabinet for 5 min. The surface humidity of the part is controlled, and the purpose is to improve the bonding rate and the compactness of the part and a filling material (eutectic point urea mixture).

Preparing before casting, selecting a flat plate with a smooth surface as a bottom plate for placing impeller parts, paving a piece of kraft paper on the flat plate to prevent the filling material from being combined with the bottom plate, then surrounding the parts by thin-wall steel sheets (the thickness is about 0.5mm) to form a tubular shape, and attaching the steel sheets to the impeller parts as much as possible, so that the filling material can be uniformly arranged in the circumferential direction.

One deck solid urea is spread to a whole circle of contacting at part and kraft paper, and this layer of solid urea's thickness is about 4mm, and solid urea has the heat absorption effect, can open the cooling effect, reduces the deformation of blade and then chooses for use the fibre (draw materials easily, select cloth silk or slender cloth, length is about 173mm), and its fibre is put along the extending direction of blade, can improve the bonding rate of filling material urea.

At normal temperature, a steel basin is used for containing urea and propionamide, and the ratio of urea to propionamide is 1:1, mixing the mixture by mass as a eutectic point urea mixture, gradually heating the mixture to reach the eutectic point of the mixture when the mixture is heated to 70 ℃, melting the eutectic point urea mixture as a filling material, and continuously heating the mixture for about 20min to prevent the liquefied eutectic point urea mixture from cooling during pouring, wherein the filling material can be melted for multiple times.

Pouring the mixture of eutectic point urea melted into liquid into a closed tubular structure formed by steel sheets, wherein the pouring height is about 15mm, then spreading a layer of solid urea on the liquid surface, the solid urea has heat absorption effect and can reduce the temperature and reduce the deformation of blades, and circulating 4 times of the fifth step to fill the impeller parts as shown in figure 2.

Sixthly, the whole part can be processed after the temperature of the whole part is cooled down, and the processing time T of the blank cast by the eutectic point urea mixture is not more than 24 hours, namely: t is less than or equal to 24h, and the humidity E is between 20 and 60 percent.

The above is the working principle and structural characteristics of this embodiment, and all such devices manufactured according to this structural scheme belong to the protection scope of the present invention.