Exhaust structure of low-pressure casting motor rotor mold and exhaust structure determination method

Abstract

The invention relates to an exhaust structure of a low-pressure casting motor rotor mold and an exhaust structure determination method, belongs to the technical field of low-pressure casting, and solves the technical problem that end ring air holes are formed due to high liquid lifting speed and unreasonable mold exhaust design of a low-pressure casting motor rotor. According to the solution, the exhaust structure of the low-pressure casting motor rotor mold comprises an upper mold, a plurality of axially-through mounting holes are formed in the exhaust face of the back of the upper mold, and exhaust plugs are mounted in the mounting holes; and the plurality of mounting holes are distributed at positions opposite to the balance column cavities in a one-to-one correspondence manner and / or the plurality of mounting holes are distributed between the balance column cavities and the fan blade cavities. Compared with the prior art, the exhaust plugs are arranged at the multiple positions of the exhaust face of the back of the upper die, so that the exhaust area is increased, exhaust is smooth, the defect that end ring air holes appear in a product is overcome, the exhaust structure of the die is determined through the exhaust structure determining method, the exhaust structure design is more appropriate, and smooth exhaust is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of low-pressure casting, and particularly relates to an exhaust structure of a low-pressure casting motor rotor mold and a method for determining the exhaust structure. Background Art

[0002] Generally, the cage rotor is filled with aluminum liquid into the cavity composed of the punching slot and the mold end ring cavity to form a complete rotor winding. The pore defects of the motor cast aluminum rotor directly affect the rotor resistance, and then affect the efficiency, temperature rise and other technical design indicators of the whole machine. There are three main structures of the motor cast aluminum end ring structure, namely 1: fan blade and balance column hybrid type; 2: balance column type; 3: no fan blade, no balance column type. The pores in the motor cast aluminum end ring structure are a factor affecting the resistivity of the cast aluminum rotor. During the casting process of the rotor, the liquid rise and filling speed are fast, the aluminum liquid is turbulent, and the air in the cavity is drawn into the aluminum liquid, forming pores after cooling. In addition, due to the unreasonable exhaust design of the mold, during the process of aluminum liquid filling, the back pressure generated by the gas at the top of the cavity is too large, and the gas is mixed into the aluminum liquid, forming pores when cooling. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an exhaust structure for a low-pressure casting motor rotor mold and a method for determining the exhaust structure, thereby solving technical problems such as the formation of end ring pores in the low-pressure casting motor rotor due to fast liquid rising speed and unreasonable mold exhaust design.

[0004] In order to solve the above problems, the technical solution of the present invention is: an exhaust structure of a low-pressure casting motor rotor mold, including an upper mold, and a plurality of axially penetrating mounting holes are opened on the exhaust surface of the back of the upper mold, and exhaust plugs are installed in the mounting holes; the plurality of mounting holes are distributed one by one at the position directly opposite to the balance column cavity and / or the plurality of mounting holes are distributed between the balance column cavity and the fan blade cavity.

[0005] Optionally, for the end ring structure of the fan blade and the balancing column hybrid type, an exhaust plug is provided between the fan blade cavity and the balancing column cavity of the upper mold.

[0006] Optionally, center lines of several balancing columns and center lines of several exhaust plugs all pass through the same circular contour.

[0007] Optionally, for the end ring structure of the balancing column type, an exhaust plug is provided at a position directly opposite to the balancing column cavity of the upper mold.

[0008] Optionally, a plurality of radial exhaust grooves, exhaust ring grooves and a plurality of radial exhaust through grooves are provided on the exhaust surface on the back of the upper mold, the inner side of the exhaust ring groove is connected with the outer ends of the plurality of radial exhaust grooves, the outer side of the exhaust ring groove is connected with the inner ends of the plurality of radial exhaust through grooves, and the outer ends of the radial exhaust through grooves pass through the outer side wall of the upper mold; a plurality of radial exhaust grooves are divergently distributed on the exhaust surface, and a plurality of radial exhaust through grooves are divergently distributed on the exhaust surface.

[0009] Optionally, the width of the exhaust ring groove is not less than 5 mm.

[0010] Optionally, for the end ring structure of the fan blade balance column hybrid type, the width B1 of the radial exhaust groove is the fan blade width + 4mm, and the depth H1 of the radial exhaust groove is 0.08mm-0.12mm.

[0011] Optionally, the width B of the radial exhaust groove is 10 mm-15 mm, and the depth H of the radial exhaust groove is 5 mm-10 mm.

[0012] Another object of the present invention is to provide a method for determining the exhaust structure of a low-pressure casting motor rotor mold, comprising the following steps: Step 1: Calculate the exhaust volume of the motor cast aluminum rotor: The cavity volume of the low-pressure cast aluminum rotor includes the upper and lower mold cavities and the sum of the cavity in the riser; set the aluminum weight of the rotor to W 铝 , the nozzle weight is designed to be 20%-30% of the aluminum weight. At the beginning of low-pressure casting, the aluminum liquid is slowly raised during the liquid lifting stage to exhaust all the air in the liquid lifting pipe in advance. This part of the volume is ignored during calculation; the total volume that needs to be discharged is ▽ 总 , where the ratio is 0.25, W 铝 The unit is kg; the calculation formula is as follows: ▽ 型腔 =(W 铝 +0.25× W 铝 ) / ρ 铝 =1.25W 铝 / ρ 铝 K 温升 = (80 × 0.00367) = 0.29 ▽ 总 =▽ 型腔 × (1 + 0.29) = 1.29 ▽ 型腔 =1.61× W 铝 / ρ 铝 (cm³) =670 W 铝 (cm³); In the above formula, 80 refers to the temperature difference between the aluminum liquid and the iron core, 0.00367 refers to the volume expansion coefficient, 1.61 is the product of 1.25 and 1.29, and 670 is the result of the calculation after substituting the previous values; the ratio is 0.25, which is the ratio of the rotor aluminum weight taken when designing the nozzle; Step 2: Calculate the minimum exhaust area: Assuming that the minimum exhaust velocity of air is equal to the rising velocity of aluminum liquid, according to the calculated volume ▽ 型腔 , divided by the casting time t and speed V, the formula is as follows: , Among them, the casting time t ranges from 8s to 10s. The above formula can be used to calculate the required minimum exhaust area; Step 3. Determine the exhaust structure of the mold according to the minimum exhaust area calculated in step 2: For the end ring structure of the fan blade balance column hybrid type, an exhaust plug is set along the center line of the balance column and between each balance column cavity of the upper mold and the fan blade cavity to increase the exhaust volume; For the end ring structure of the balance column type, in addition to the exhaust plug at the bottom of the balance column, the number of exhaust plugs is increased to increase the exhaust volume according to the number and position distribution of the balance columns; The number of exhaust plugs to be added is confirmed by the calculated minimum exhaust area value.

[0013] Optionally, in step 1, the speed range of lifting the aluminum liquid is 50 mm / s-150 mm / s.

[0014] Compared with the prior art, the present invention has the following beneficial effects: In order to ensure product quality and eliminate the influence of pores on the resistivity of the cast rotor, the present invention adopts the process means such as mold structure design and aluminum liquid treatment to solve the problem. By setting an exhaust plug on the mold, and opening radial exhaust grooves and exhaust ring grooves, the exhaust volume is increased, thereby avoiding the occurrence of end ring pore defects, ensuring product quality, and eliminating the influence of pores on the resistivity of the cast rotor; by calculating the exhaust volume of the mold, the mold exhaust structure is determined to ensure smooth mold exhaust and avoid the generation of end ring pores. Solve the motor rotor casting pore defects and provide a process solution for green manufacturing. Green manufacturing mainly refers to high-efficiency product manufacturing, low energy consumption, high-efficiency manufactured products, and corresponding reduction of carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is an end ring structure of a balanced column type of wind blade; Figure 2 It is a balanced column-type end ring structure; Figure 3 It is an end ring structure without blades and balanced column type; Figure 4 is a three-dimensional schematic diagram of the exhaust plug; Figure 5 It is a schematic diagram of the structure of the upper mold back (balanced column type end ring structure or bladeless balanced column type end ring structure); Figure 6 This is a schematic diagram of the structure of the upper mold back (the fan blade balance column hybrid integrated end ring structure); Figure 7 This is a cross-sectional diagram of the upper mold (the wind blade balance column hybrid integrated end ring structure); Figure 8 This is a front view of the upper mold (the integrated end ring structure of the wind blade balance column).

[0016] Figure numerals: 1. upper mold; 11. exhaust ring groove; 12. radial exhaust groove; 13. radial exhaust through groove; 14. mounting hole; 15. balance column cavity; 16. fan blade cavity; 2. exhaust plug; 21. exhaust slot; 3. end ring structure; 31. fan blade; 32. balance column. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0018] Example 1: Figure 1-Figure 8 As shown, this embodiment provides an exhaust structure of a low-pressure casting motor rotor mold, including an upper mold 1, and a plurality of axially penetrating mounting holes 14 are opened on the exhaust surface of the back of the upper mold 1, and exhaust plugs 2 are installed in the mounting holes 14; the plurality of mounting holes 14 are distributed one by one at the position opposite to the balance column cavity 15 and / or the plurality of mounting holes 14 are distributed between the balance column cavity 15 and the fan blade cavity 16.

[0019] In this way, by arranging exhaust plugs 2 at multiple positions on the exhaust surface at the back of the upper mold 1, the number of exhaust plugs 2 is increased, thereby increasing the exhaust area, venting is smooth, and the defect of end ring air holes is avoided in the product.

[0020] In the exhaust structure of a low-pressure casting motor rotor mold of this embodiment, for the end ring structure 3 of the fan blade and balance column hybrid type, an exhaust plug 2 is provided between the fan blade cavity 16 and the balance column cavity 15 of the upper mold 1.

[0021] In the exhaust structure of a low-pressure casting motor rotor mold of this embodiment, the center lines of a plurality of balancing columns 32 and the center lines of a plurality of exhaust plugs 2 all pass through the same circular contour. This arrangement makes the exhaust plugs 2 evenly distributed and has a good exhaust effect.

[0022] In the exhaust structure of a low-pressure casting motor rotor mold of this embodiment, for the end ring structure 3 of the balance column type, an exhaust plug 2 is provided at a position directly opposite to the balance column cavity 15 of the upper mold 1.

[0023] In the exhaust structure of a low-pressure casting motor rotor mold of the present embodiment, a plurality of radial exhaust grooves 12, exhaust ring grooves 11 and a plurality of radial exhaust through grooves 13 are opened on the exhaust surface on the back of the upper mold 1, the inner side of the exhaust ring groove 11 is connected with the outer ends of the plurality of radial exhaust grooves 12, the outer side of the exhaust ring groove 11 is connected with the inner ends of the plurality of radial exhaust through grooves 13, and the outer ends of the radial exhaust through grooves 13 pass through the outer side wall of the upper mold 1; a plurality of radial exhaust grooves 12 are distributed divergently on the exhaust surface, and a plurality of radial exhaust through grooves 13 are distributed divergently on the exhaust surface.

[0024] In this way, the radial exhaust groove 12, the exhaust ring groove 11, the radial exhaust through groove 13 and the exhaust plug 2 are combined to exhaust, thereby increasing the exhaust area and facilitating smooth exhaust. The outer diameter of the exhaust ring groove 11 is D1 and D2, and the depth is H.

[0025] In the exhaust structure of the low-pressure casting motor rotor mold of this embodiment, the width of the exhaust ring groove 11 is not less than 5 mm. This arrangement allows the mold to be exhausted smoothly.

[0026] In the exhaust structure of a low-pressure casting motor rotor mold of this embodiment, for the end ring structure 3 of the fan blade balance column hybrid type, the width B1 of the radial exhaust groove 12 is the fan blade width + 4mm, and the depth H1 of the radial exhaust groove 12 is 0.08mm-0.12mm.

[0027] In the exhaust structure of a low-pressure casting motor rotor mold of this embodiment, the width B of the radial exhaust groove 13 is 10mm-15mm, and the depth H of the radial exhaust groove 13 is 5mm-10mm.

[0028] In the exhaust structure of a low-pressure casting motor rotor mold of this embodiment, in order to reduce exhaust resistance and make exhaust smooth, the number of radial exhaust slots 13 is 6-8 and is evenly distributed.

[0029] In the exhaust structure of a low-pressure casting motor rotor mold of this embodiment, the exhaust plug 2 has a plurality of exhaust slots 21, thereby improving the exhaust efficiency.

[0030] Embodiment 2: This embodiment provides a method for determining the exhaust structure of a low-pressure casting motor rotor mold to determine the exhaust structure in Embodiment 1, comprising the following steps: Step 1: Calculate the exhaust volume of the motor cast aluminum rotor: The cavity volume of the low-pressure cast aluminum rotor includes the upper and lower mold cavities and the sum of the cavity in the riser; set the aluminum weight of the rotor to W 铝 , the nozzle weight is designed to be 20%-30% of the aluminum weight. At the beginning of low-pressure casting, the aluminum liquid is slowly raised during the liquid lifting stage to exhaust all the air in the liquid lifting pipe in advance. This part of the volume is ignored during calculation; the total volume that needs to be discharged is ▽ 总, where the ratio is 0.25. 铝 The unit is kg; the calculation formula is as follows: ▽ 型腔 =(W 铝 +0.25× W 铝 ) / ρ 铝 =1.25W 铝 / ρ 铝 K 温升 = (80 × 0.00367) = 0.29 ▽ 总 =▽ 型腔 × (1 + 0.29) = 1.29 ▽ 型腔 =1.61× W 铝 / ρ 铝 (cm³) =670 W 铝 (cm³); In the above formula, 80: refers to the temperature difference between the aluminum liquid and the iron core, and the minimum value is obtained in this embodiment. 0.00367 refers to the volume expansion coefficient. 1.61 is the product of 1.25 and 1.29, and 670 is the result of the calculation after substituting the previous values. The ratio is 0.25: This is the ratio of the rotor aluminum weight taken when designing the nozzle, which is generally 20%-30%. The intermediate value of 0.25 is taken in this embodiment.

[0031] Step 2: Calculate the minimum exhaust area: Since the rotor core can only be cast after being heated in the heating furnace, the temperature of the molten aluminum during casting is generally 80-120 degrees Celsius higher than the temperature of the core. During the filling stage, the air temperature rises and the gas generates back pressure. Assuming that the minimum exhaust speed of the air is equal to the rising speed of the molten aluminum, according to the calculated volume ▽ 型腔 , divided by the casting time t and speed V, the formula is as follows: , Among them, the casting time t ranges from 8s to 10s. The above formula can be used to calculate the required minimum exhaust area; Step 3, determine the mold exhaust structure according to the minimum exhaust area calculated in step 2: For the end ring structure 3 of the fan blade balance column hybrid type, along the center line of the balance column 32, between each balance column cavity 15 and the fan blade cavity 16 of the upper mold 1, set an exhaust plug 2 to increase the exhaust volume, which can effectively solve the exhaust problem at the root of the fan blade 31 and the balance column 32; for the end ring structure 3 of the balance column type, in addition to the exhaust plug 2 at the bottom of the balance column 32, according to the number and position distribution of the balance column 32, increase the number of exhaust plugs 2 to increase the exhaust volume; the number of exhaust plugs 2 is determined by the calculated minimum exhaust area value to confirm the number of exhaust plugs to be added. The principle of selecting the exhaust plug 2 should be to select an exhaust plug 2 with a large diameter and multiple exhaust surfaces according to the position structure size.

[0032] The exhaust structure of the mold is determined by calculating the exhaust volume. The process method is simple to operate, low in cost, and the exhaust structure design is more suitable, ensuring smooth exhaust. In the selection of the exhaust surface, for the end ring structure 3 of the fan blade balance column type structure, generally there is a height difference between the fan blade and the balance column, and the exhaust surface is generally selected at the tail of the balance column 32 and the fan blade 31. Assuming that there is no turbulence in the entire low-pressure casting process, when the aluminum liquid reaches the bottom of the balance column, the exhaust surface of the balance column 32 will be closed, and at the same time, the fan blade cavity 16 will also enter part of the aluminum liquid, closing the exhaust channel. At this time, if there is still gas between the balance column 32 and the fan blade 31 that has not been exhausted, as the aluminum liquid continues to rise and enters the pressure holding, the fan blade exhaust surface is closed, and the gas will not be able to be discharged. It will be compressed to the upper part of the end ring or enter the fan blade cavity 16, and finally form pores. The cavity gas expands due to heat, and its volume increases, and its volume expansion coefficient is about 0.00367 / ℃. For the end ring structure 3 of the balanced column type structure and the end ring structure 3 without fan blades and balanced column type, the exhaust surface is on a plane, that is, at the bottom of the balanced column 32 or the upper plane of the end ring, and the exhaust area needs to be increased to meet the requirements of rotor exhaust.

[0033] In the method for determining the exhaust structure of a low-pressure casting motor rotor mold of this embodiment, in step 1, the speed range of the aluminum liquid is 50 mm / s-150 mm / s.

Claims

1. The exhaust structure of the low-pressure casting motor rotor mold is characterized by: The invention comprises an upper mold (1), wherein a plurality of axially penetrating mounting holes (14) are provided on the exhaust surface at the back of the upper mold (1), and an exhaust plug (2) is installed in the mounting hole (14); the plurality of mounting holes (14) are distributed one by one at positions directly opposite to the balance column cavity (15) and / or the plurality of mounting holes (14) are distributed between the balance column cavity (15) and the fan blade cavity (16).

2. The exhaust structure of the low-pressure casting motor rotor mold according to claim 1 is characterized in that: For the integrated end ring structure (3) of the fan blade and the balance column, an exhaust plug (2) is provided between the fan blade cavity (16) and the balance column cavity (15) of the upper mold (1).

3. The exhaust structure of the low-pressure casting motor rotor mold according to claim 2 is characterized in that: The center lines of the plurality of balancing columns (32) and the center lines of the plurality of exhaust plugs (2) all pass through the same circular contour.

4. The exhaust structure of the low-pressure casting motor rotor mold according to claim 1 is characterized in that: For the end ring structure (3) of the balance column type, an exhaust plug (2) is provided at a position directly opposite to the balance column cavity (15) of the upper mold (1).

5. The exhaust structure of the low-pressure casting motor rotor mold according to claim 1 is characterized in that: A plurality of radial exhaust grooves (12), an exhaust ring groove (11) and a plurality of radial exhaust through grooves (13) are provided on the exhaust surface at the back of the upper die (1); the inner side of the exhaust ring groove (11) is connected to the outer ends of the plurality of radial exhaust grooves (12); the outer side of the exhaust ring groove (11) is connected to the inner ends of the plurality of radial exhaust through grooves (13); the outer ends of the radial exhaust through grooves (13) penetrate the outer side wall of the upper die (1); the plurality of radial exhaust grooves (12) are distributed divergently on the exhaust surface; and the plurality of radial exhaust through grooves (13) are distributed divergently on the exhaust surface.

6. The exhaust structure of the low-pressure casting motor rotor mold according to claim 5, characterized in that: The width of the exhaust ring groove (11) is not less than 5 mm.

7. The exhaust structure of the low-pressure casting motor rotor mold according to claim 5, characterized in that: For the end ring structure (3) of the fan blade balance column hybrid type, the width B1 of the radial exhaust groove (12) is the fan blade width + 4 mm, and the depth H1 of the radial exhaust groove (12) is 0.08 mm-0.12 mm.

8. The exhaust structure of the low-pressure casting motor rotor mold according to claim 5, characterized in that: The width B of the radial exhaust groove (13) is 10 mm to 15 mm, and the depth H of the radial exhaust groove (13) is 5 mm to 10 mm.

9. A method for determining the exhaust structure of a low-pressure casting motor rotor mold, characterized in that: The following steps are involved: Step 1: Calculate the exhaust volume of the motor cast aluminum rotor: The cavity volume of the low-pressure cast aluminum rotor includes the upper and lower mold cavities and the sum of the cavity in the riser; set the aluminum weight of the rotor to W 铝 , the nozzle weight is designed to be 20%-30% of the aluminum weight. At the beginning of low-pressure casting, the aluminum liquid is slowly raised during the liquid lifting stage to exhaust all the air in the liquid lifting pipe in advance. This part of the volume is ignored during calculation; the total volume that needs to be discharged is ▽ 总 , where the ratio is 0.25, W 铝 The unit is kg; the calculation formula is as follows: ▽ 型腔 =(W 铝 +0.25× W 铝 ) / p 铝 =1.25W 铝 / r 铝 K 温升 =（80×0.00367）=0.29 ▽ 总 =▽ 型腔 ×（1+0.29）=1.29▽ 型腔 =1.61×W 铝 / r 铝 (cm³) =670W 铝 (cm³); In the above formula, 80 refers to the temperature difference between the aluminum liquid and the iron core, 0.00367 refers to the volume expansion coefficient, 1.61 is the product of 1.25 and 1.29, and 670 is the result of the calculation after substituting the previous values; the ratio is 0.25, which is the ratio of the rotor aluminum weight taken when designing the nozzle; Step 2: Calculate the minimum exhaust area: Assuming that the minimum exhaust velocity of air is equal to the rising velocity of aluminum liquid, according to the calculated volume ▽ 型腔 , divided by the casting time t and speed V, the formula is as follows: ， Among them, the casting time t ranges from 8s to 10s. The above formula can be used to calculate the required minimum exhaust area; Step 3, determine the exhaust structure of the mold according to the minimum exhaust area calculated in step 2: for the end ring structure of the fan blade balance column hybrid type, along the center line of the balance column, between each balance column cavity (15) and the fan blade cavity (16), an exhaust plug (2) is set in the upper mold (1) to increase the exhaust volume; for the end ring structure (3) of the balance column type, in addition to the exhaust plug (2) at the bottom of the balance column (32), according to the number and position distribution of the balance columns (32), the number of exhaust plugs (2) is increased to increase the exhaust volume; the number of exhaust plugs (2) to be increased is determined by the minimum exhaust area value calculated.

10. The method for determining the exhaust structure of a low-pressure casting motor rotor mold according to claim 9, characterized in that: In step 1, the speed range of the aluminum liquid is 50 mm / s -150 mm / s.

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