CN219233911U - Die casting die for producing speed reducer gears - Google Patents

Abstract

This application relates to the technical field of die-casting molds, in particular to a die-casting mold used for the production of reducer gears, which includes a fixed mold connected to a die-casting machine for mutual bonding for mold clamping, a movable mold, and a mold for forming The cavity is used for injecting the metal solution into an upper core and a lower core, the lower core is arranged on the side wall of the fixed mold facing the movable mold, and the upper mold is arranged on the side of the movable mold facing the fixed mold wall, the upper core and the lower core form a cavity when the mold is closed, the cavity is consistent with the shape and size of the reducer gear, the lower core is provided with a lower cavity, and the lower cavity The inner wall of the bottom of the bottom is fixed with a filling column, and the circumferential side wall of the filling column near the bottom of the lower cavity is provided with a chamfer, and the chamfer is used to contact the molten metal in the cavity and form a spline groove Mouth chamfer. The present application has the effect of reducing the probability of surface scratches when chamfering is formed on the inner wall of the spline groove.

Description

A die-casting mold for the production of reducer gears

technical field

The present application relates to the technical field of die-casting molds, in particular to a die-casting mold used for the production of reducer gears.

Background technique

The gear of the reducer is an important transmission part of the reducer. The gear of the reducer has high requirements on the overall quality of the overall structure during the production process, especially the hardness and surface finish of the gear of the reducer. The gear of the reducer is thin-walled and structurally Relatively complex parts are usually made of metal materials. During production, the metal solution is poured into the die-casting mold, and the gear casting of the reducer is obtained after cooling and demoulding.

As shown in Figure 1, the gear of an existing reducer includes a connecting wheel a and an engaging toothed disc b. The disk b is concentrically arranged, and the outer diameter of the meshing toothed disk b is smaller than that of the connecting wheel a, and a plurality of meshing teeth b1 are evenly distributed on the outer wall of the meshing toothed disk b, and the meshing toothed disk b is set far away from the side wall of the connecting wheel There is a ring groove b2, and a plurality of communication holes b3 are opened in the ring groove b2, and the plurality of communication holes b3 are uniformly arranged around the axis of the connecting wheel a, and the communication holes b3 run through the two opposite sides of the meshing wheel b and the connecting wheel a The opening of the ring groove b2 separates the center of the meshing wheel b to obtain a raised disc b4. The raised disc b4 is provided with a spline groove b5, and the spline groove b5 runs through the raised wheel b4 and the connecting wheel a. Two opposite side walls, the gear shaft on the reducer is used for the sheathing of the gear of the reducer. When the gear of the reducer is sheathed on the gear shaft, the gear shaft is inserted into the spline groove b5. In order to facilitate the insertion of the gear shaft, the inner wall of the notch of the spline groove b5 Chamfering is required. In the existing ones, the gears of the reducer are usually processed manually after die-casting. During the processing, the staff needs to control the size of the chamfered slope, so as to avoid the excessively large slope formed during the chamfering process, which will cause the gear material of the reducer to wear Too much, and it is easy to scratch the edge side wall of the notch of the spline groove at the same time.

With regard to the related technologies mentioned above, the inventor believes that it is easy to scratch the side wall of the opening edge of the spline groove due to artificial chamfering.

Utility model content

In order to reduce the probability of surface scratches caused by chamfering at the inner wall of the spline groove, the present application provides a die-casting mold for the production of reducer gears.

A die-casting mold for the production of reducer gears provided by the application adopts the following technical scheme:

A die-casting mold for the production of reducer gears, including a fixed mold connected to a die-casting machine for mutual fit for mold clamping, a movable mold, and an upper core and a lower mold for forming a cavity for injection of metal solution core, the lower core is arranged on the side wall of the fixed mold towards the movable mold, the upper core is arranged on the side wall of the movable mold towards the fixed mold, the upper core and the lower mold The core forms a cavity when the mold is closed, and the cavity is consistent with the shape and size of the reducer gear. The lower core is provided with a lower cavity, and the bottom inner wall of the lower cavity is fixed with a filling column. The circumferential side wall of the column near the bottom of the lower cavity is provided with a chamfer, and the chamfer is used for contacting the liquid metal in the cavity and forming a chamfer of the spline groove.

By adopting the above technical scheme, when the molten metal enters the mold cavity and gradually cools down, the molten metal forms a casting mold in the cavity with the same shape and volume as the gear of the reducer, because the molten metal is attached to the filled column when it is cooled and formed. On the chamfered surface, the inner wall of the spline groove opening of the reducer gear forms a chamfered surface, which does not need to be chamfered after the casting is removed, thereby reducing the probability of scratching the surface of the reducer gear during the chamfering process.

Optionally, the upper core has a plurality of upper cavities facing the side wall of the lower core, and the lower core has a plurality of lower cavities facing the side wall of the upper core, the The number of the lower cavity corresponds to the upper cavity one by one. When the mold is closed, the upper cavity cooperates with the corresponding lower cavity to form a cavity.

By adopting the above technical scheme, multiple upper cavities and multiple lower cavities are molded to form cavities. Since there are multiple cavities, multiple castings can be obtained in one mold clamping die-casting, which improves the speed of the reducer gear. Casting machining efficiency.

Optionally, an overflow groove is provided on the edge side wall of each lower cavity, and the overflow groove communicates with the lower cavity for the molten metal to fill the cavity and then flow in.

By adopting the above technical scheme, the opening of the overflow tank makes the metal solution fill the lower cavity, and the metal solution overflows into the overflow tank, so that the metal solution in the overflow tank forms a connecting block connected with the casting. When demoulding, the connecting block is pulled out to drive the casting away from the lower cavity, and the surface of the casting is not easy to be scratched.

Optionally, the side wall of the lower core facing the upper core is provided with a solution guide groove, the solution guide groove communicates with each of the lower mold cavities, and the solution guide groove includes a first flow channel and a second flow channel. Two flow channels, the inner wall of the connection between the first flow channel and the second flow channel is provided with a buffer arc surface.

By adopting the above technical scheme, the solution guide groove guides the metal solution to flow into the lower cavity, and gradually fills the cavity. Since the inner wall of the connection between the first flow channel and the second flow channel is provided with a buffer arc surface, the buffer arc surface Buffer drainage is performed when the metal solution quickly flows to the buffer arc surface, so that the fluidity of the metal solution when flowing in the solution guide groove is better, so that the cavity gap can be filled.

Optionally, a communication groove is provided between the solution guide groove and each of the lower mold cavities, the bottom of the communication groove is inclined upward, and the bottom of the notch close to the communication groove is The side wall is the lowest end, and the slot where the communication groove is close to the lower cavity is the highest end.

By adopting the above technical scheme, the communication groove transmits the metal solution from the solution guide groove to the lower cavity. Since the bottom of the metal communication groove is inclined, when the metal solution flows toward the lower cavity, the metal solution needs to be located in the communication channel. Only when the liquid level in the tank rises gradually can it enter the connecting tank, so as to buffer the moment when the metal solution flows into the lower cavity, so that the metal solution flows evenly and slowly into the lower cavity.

Optionally, a plurality of first exhaust grooves are opened on the side wall of the lower core facing the upper core, and the plurality of first exhaust grooves communicate the solution guide groove with the outside air.

By adopting the above technical scheme, the first exhaust groove communicates the solution guide tank with the outside air, so that when the metal solution flows in the solution guide tank, the air pressure in the metal solution tank is not easy to generate obstacles to the flow of the metal solution, which facilitates the flow of the metal solution. Flow into the cavity along the solution guide groove.

Optionally, a plurality of second exhaust grooves are opened on the side wall of the lower core facing the upper core, and the plurality of second exhaust grooves communicate the overflow groove with the outside air.

By adopting the above technical solution, the second vent hole connects the overflow tank with the outside air, so that the pressure in the overflow tank is not easy to form and hinder the inflow of the metal solution, so that the metal solution has better fluidity, so that it can be quickly The overflow tank is full.

Optionally, a plurality of positioning rods are provided on the lower core, positioning holes are opened on the side wall of the upper core towards the side wall of the lower core, and the number of the positioning holes is equal to the number of the positioning rods. In one-to-one correspondence, the positioning holes are inserted into the positioning rods, and when the positioning rods are inserted into the positioning holes, the slots of the upper cavity and the lower cavity are coincidently aligned.

By adopting the above technical solution, the positioning rod is inserted into the positioning hole, so that the openings of the upper cavity and the lower cavity can match, so as to improve the precision of the shape when the molten metal in the cavity is cooled to form a casting.

In summary, the present application includes at least one of the following beneficial technical effects:

1. When the metal solution enters the cavity and gradually cools down, the metal solution forms a mold in the cavity with the same shape and volume as the gear of the reducer. Since the metal solution fits on the inclined surface of the filled column during cooling and molding, Therefore, a chamfer is formed on the inner wall of the spline groove opening of the reducer gear, and it is not necessary to perform chamfering after the casting is removed, thereby reducing the probability of scratching the surface of the reducer gear during the chamfering process;

2. The opening of the overflow tank makes the metal solution fill the lower cavity, and the metal solution overflows into the overflow tank, so that the metal solution in the overflow tank forms a connecting block connected with the casting. When the casting is demoulded Pull the connecting block to drive the casting away from the lower cavity, and it is not easy to scratch the surface of the casting;

3. The solution guide groove guides the metal solution into the lower cavity, and gradually fills the cavity. Since the inner wall of the connection between the first flow channel and the second flow channel is provided with a buffer arc surface, the buffer arc surface can quickly absorb the metal solution. Buffer drainage is performed when flowing to the buffer arc surface, so that the fluidity of the metal solution when flowing in the solution guide groove is better, so that the cavity gap can be filled.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of a reducer gear in the present application.

Fig. 2 is the exploded view of movable mold, upper mold core, lower mold core and fixed mold in the present application.

Fig. 3 is a cross-sectional view of the upper core and the lower core in the present application along the longitudinal direction along the front-back direction.

Fig. 4 is an enlarged view at A in Fig. 3 .

Fig. 5 is a side view exploded view of the movable mold, the upper mold core, the lower mold core and the fixed mold in the present application.

Fig. 6 is a partial structural schematic diagram of the upper core in the present application.

Figure 7 is an exploded view of the pouring cylinder, the movable mold, and the fixed mold in the present application.

Fig. 8 is a side structural schematic view of the lower core in the present application.

Explanation of reference signs: 1, fixed mold; 11, lower embedding groove; 12, abutment column; 121, pouring groove; 2, moving mold; 21, upper embedding groove; 22, socket hole; 23, pouring cylinder; 231 , contact part; 232, socket part; 3, upper core; 31, upper cavity; 32, forming protrusion; 321, second bevel; 33, positioning hole; 4, lower core; 41, lower Cavity; 411, connecting groove; 42, filled column; 421, inverted slope; 43, solution guide groove; 431, first flow channel; 432, second flow channel; 433, buffer arc surface; 44, overflow groove; 441 , connecting block; 45, first exhaust groove; 46, second exhaust groove; 47, positioning rod; 5, mold cavity.

Detailed ways

The present application will be described in further detail below in conjunction with accompanying drawings 2-8. In this embodiment, the direction indicated by the coordinate axis z in the figure is upward, the direction opposite to the z axis is downward, the direction indicated by the y axis is the front side, and the direction opposite to the y axis is the rear side.

The embodiment of the present application discloses a die-casting mold used for gear production of a reducer. Referring to Figure 2-4, the die-casting mold used for the production of reducer gears includes a fixed mold 1, a movable mold 2, an upper core 3 and a lower core 4, the lower core 4 is connected to the fixed mold 1, and the upper core 3 is connected to the movable mold. The mold 2 is connected, and when the fixed mold 1 and the movable mold 2 move in the vertical direction to close the mold, the upper core 3 and the lower core 4 are attached to form a cavity 5, and the cavity 5 is used for the injection of molten metal to form the gear of the reducer. Castings with the same shape and size, the lower core 4 is provided with a lower cavity 41, and the bottom inner wall of the lower cavity 41 is fixed with a filling column 42, and the circumferential side wall of the filling column 42 near the bottom inner wall of the lower cavity 41 is opened. There is a bevel 421, and the spline groove is formed when the molten metal is formed on the side of the filling column 42, and the notch chamfering of the spline groove is formed at the bevel 421, thereby eliminating the subsequent step of chamfering at the notch of the spline groove of the casting , so that it is not easy to cause surface scratches due to chamfering.

Referring to Figure 2 and Figure 5, the upper side wall of the fixed mold 1 is provided with a lower embedding groove 11, the shape of the notch of the lower embedding groove 11 is consistent with the shape of the lower core 4, and the lower embedding groove 11 is used for the embedding of the lower core 4 , the lower side of the movable mold 2 is provided with an upper embedding groove 21, and the upper embedding groove 21 is used for the embedding of the upper core 3. When the upper core 3 is located in the upper embedding groove 21, the horizontal circumferential side wall of the upper core 3 and the upper The horizontal inner wall of the embedded groove 21 is in contact with each other, the lower side wall of the upper core 3 is provided with an upper cavity 31, the opening of the upper cavity 31 is aligned with the lower cavity 41, and the fixed mold 1 and the movable mold 2 are respectively aligned with the die casting Machine connection, under the drive of the die-casting machine, the molds are moved in opposite directions, and the reverse separation is demoulding. When the movable mold 2 and the fixed mold 1 are clamped, the opposite side walls of the upper core 3 and the lower core 4 are in contact with each other. The upper cavity 31 is aligned with the opening of the lower cavity 41 and forms the cavity 5 .

Referring to Fig. 5 and Fig. 6, the inclined surface 421 on the filling column 42 is inclined from top to bottom toward the direction away from the axis of the filling column 42, in order to make the inner wall of the notch on the other side of the inter-flower groove also be able to be formed when the casting is formed. With a chamfer angle, the inner side wall facing the lower side of the upper cavity 31 is integrally provided with a forming protrusion 32, the shape of the forming protrusion 32 is consistent with the vertical section of the filling column 42, and the vertical section of the filling column 42 Consistent with the shape of the opening of the spline groove, when the upper core 3 and the lower core 4 abut, the upper end surface of the filling column 42 abuts against the lower side wall of the forming protrusion 32, and the lower edge of the forming protrusion 32 is provided with a The second bevel 321 , the inclination direction of the second bevel 321 is opposite to the inclination direction of the bevel 421 , so that when the metal solution is formed in the cavity 5 , the inner walls of the two slots of the spline groove are formed with chamfers.

2 and 5, in order to improve the die-casting production efficiency of the reducer gear, the upper side wall of the lower core 4 is provided with a plurality of lower cavities 41, and correspondingly, the lower side wall of the upper core 3 is provided with a plurality of upper cavities. Die cavity 31, the quantity of upper die cavity 31 corresponds to the quantity of lower die cavity 41 one by one, in the present embodiment, the quantity of lower die cavity 41 is introduced with eight examples, and eight upper die cavities 31 are divided into two rows, There are four in each row, and there is an interval between two adjacent lower die cavities 41 .

Referring to Fig. 5, in order to make the opening of the upper cavity 31 and the lower cavity 41 vertically aligned during mold closing, the lower side wall of the upper core 3 is provided with a plurality of positioning holes 33, and the lower core 3 is provided with a plurality of positioning holes 33. 4, a plurality of positioning rods 47 are plugged in, the number of positioning rods 47 is consistent with the positioning hole 33, the positioning hole 33 is inserted into the positioning rod 47, and when the positioning rod 47 is inserted in the positioning hole 33, the opening of the upper cavity 31 is just in line with the lower one. The openings of the cavity 41 are aligned, and the edges and inner walls of the openings coincide with each other. In the present embodiment, the quantity of positioning hole 33 rods is introduced with four as an example, and four positioning rods 47 are respectively fixed on the side walls of the lower core 4 near four diagonals, and the four positioning rods 47 are connected with the lower core. The upper sidewalls of 4 are perpendicular to each other, and the circumferential sidewalls of the positioning rods 47 are attached to the inner walls of the corresponding positioning holes 33, so that relative sliding in the horizontal direction between the upper core 3 and the lower core 4 is difficult to occur.

Referring to Fig. 7, the upper side wall of the movable mold 2 near the front edge is provided with an insertion hole 22, the insertion hole 22 runs through the upper and lower side walls of the movable mold 2, and a pouring cylinder 23 is inserted in the insertion hole 22, and the pouring cylinder 23 Including the abutment part 231 and the insertion part 232, the abutment part 231 is located at the lower side of the insertion part 232, the insertion part 232 is used for inserting into the insertion hole 22, the outer diameter of the abutment part 231 is larger than the insertion part 232, so that when the insertion part 232 is inserted into the insertion hole 22, the abutment part 231 and the movable mold 2 are abutted and limited, so that the pouring cylinder 23 and the movable mold 2 remain relatively fixed. The upper side wall near the front side edge of the fixed mold 1 is fixedly connected with the abutment column 12, and the upper end surface of the abutment column 12 is provided with a pouring groove 121, and the upper side notch of the pouring groove 121 is vertical to the end opening of the casting cylinder. Direction alignment, the upper side wall of the lower core 4 is provided with a solution guide groove 43, one side notch of the solution guide groove 43 communicates with the lower side notch of the pouring groove, and the solution guide groove 43 is connected with each lower cavity 41 They communicate with each other, so that the metal solution enters the pouring cylinder 23, the pouring tank, the solution guide tank 43 and the lower cavity 41 in turn when pouring, and slowly fills the cavity 5 in the lower cavity 41.

Referring to Fig. 8, the solution guiding groove 43 includes a first flow channel 431 and a second flow channel 432, the second flow channel 432 is provided with two, and the inner wall of the joint between the two second flow channels 432 and the first flow channel 431 may be at right angles It can also be arranged in an arc shape. In this embodiment, the arc-shaped arrangement is taken as an example. The inner wall of the connection between the first flow channel 431 and the second flow channel 432 is provided with a buffer arc surface 433. Since the metal solution guides the injected solution There is a certain flow velocity in the groove 43, and when it flows to the buffer arc surface 433, the buffer arc surface 433 buffers the metal solution so that the metal solution maintains good fluidity.

Correspondingly, each lower cavity 41 communicates with the first flow channel 431, and each lower cavity 41 communicates with the first flow channel 431 by opening a communication groove 411, and the molten metal enters the lower cavity from the first flow channel 431. Cavity 41, the groove bottom of the first runner 431 is inclined, the groove bottom of the first runner 431 has the lowest end and the highest end in the vertical direction, the lowest end communicates with the first runner 431, and the highest end communicates with the lower cavity 41 Connected, so that the communication groove 411 further buffers the metal solution flowing to the lower cavity 41, so that the metal solution flows evenly into the lower cavity 41, and the filling fit of the metal solution to the inner wall of the lower cavity 41 is better.

Referring to Fig. 8, the inner wall of each lower cavity 41 is provided with a corresponding overflow tank 44. When the metal solution in the lower cavity 41 is filled for the first time, the metal solution first flows into the overflow tank 44, and finally the entire The cavity 5 is filled, so that after cooling and forming, a connection block 441 is formed in the overflow groove 44, and the connection block 441 is connected with the side wall of the casting, so that the casting can be removed by picking the connection block 441, and it is not easy to damage the casting cause surface scratches.

Referring to Fig. 8, in order to make the molten metal in the first runner 431 have good fluidity, further, the upper side wall of the lower core 4 is provided with a first exhaust groove 45, and the first exhaust groove 45 is provided with two places, The two first exhaust grooves 45 communicate with the two first flow channels 431, and the slots at the end of the first exhaust groove 45 away from the first flow channels 431 communicate with the outside air, making it difficult to form a gap between the first flow channel 431 and the outside air. The pressure difference hinders the flow of the molten metal, and the depths of the two first exhaust grooves 45 are relatively small, so that it is not easy to cause the molten metal to flow into the first exhaust grooves 45 while exhausting the gas.

Referring to Fig. 8, the upper side wall of the lower core 4 is provided with a plurality of second exhaust grooves 46, and the number of the second exhaust grooves 46 is provided in multiples. In this embodiment, the number of the second exhaust grooves 46 is five. As an example, the five second exhaust grooves 46 communicate with the corresponding overflow grooves 44, and the two overflow grooves 44 located near the rear side and in the middle are difficult to discharge because they are surrounded by the first flow channel 431 and the second flow channel 432. The second exhaust groove 46 is opened to communicate with the outside, and the two second exhaust grooves 46 connected by the two overflow grooves 44 located near the front side are connected to each other. The opening of the second exhaust groove 46 makes The metal solution flowing into the overflow tank 44 maintains good fluidity, so that the metal solution can fill the overflow tank 44 .

The implementation principle of a die-casting mold for the production of reducer gears in the embodiment of the present application is as follows: when the movable mold 2 and the fixed mold 1 are closed, the upper cavity 31 and the lower cavity 41 cooperate to form the cavity 5, and the lower cavity 41 Filling column 42 is provided on the inner wall of the bottom of the bottom, and a slope is provided on the circumferential side wall during filling, so that after the molten metal is formed in the cavity 5, the obtained reducer gear casting is placed on the inner wall of the spline groove. Chamfering is formed, and the forming protrusion 32 in the upper cavity 31 is provided with a second chamfering surface 321, so that the inner wall of the notch on the other side of the spline groove is also formed with chamfering, so that the casting does not need to be chamfered, and it is not easy to Scratches on the casting surface due to chamfering.

All of the above are preferred embodiments of the application, and are not intended to limit the protection scope of the application. Therefore, all equivalent changes made according to the structure, shape, and principle of the application should be covered by the protection scope of the application. Inside.

Claims (8)

1. A die-casting mold for the production of reducer gears, characterized in that: it includes a fixed mold (1) connected to the die-casting machine for mutual fit for mold clamping, a movable mold (2), and a mold for forming Cavity (5) for injection of the metal solution into the upper core (3) and the lower core (4), the lower core (4) is set on the side of the fixed mold (1) facing the movable mold (2) wall, the upper core (3) is set on the side wall of the movable mold (2) facing the fixed mold (1), and the upper core (3) and the lower core (4) are A cavity (5) is formed, the cavity (5) is consistent with the shape and size of the reducer gear, the lower core (4) is provided with a lower cavity (41), and the bottom of the lower cavity (41) The inner wall is fixed with a filling column (42), and the circumferential side wall of the filling column (42) close to the bottom of the lower cavity (41) is provided with a bevel (421), and the bevel (421) is used for The liquid metal in the cavity (5) contacts and forms the notch chamfer of the spline groove. 2. A die-casting mold for the production of reducer gears according to claim 1, characterized in that: the upper core (3) has a plurality of upper cores (3) facing the side wall of the lower core (4). Cavities (31), the lower core (4) is provided with a plurality of lower cavities (41) towards the side wall of the upper core (3), the number of the lower cavities (41) is the same as the number of the The upper mold cavities (31) are in one-to-one correspondence, and when the molds are closed, the upper mold cavities (31) cooperate with the corresponding lower mold cavities (41) to form the mold cavity (5). 3. A die-casting mold for the production of reducer gears according to claim 2, characterized in that: overflow grooves (44) are provided on the edge side walls of each of the lower cavities (41), The overflow tank (44) communicates with the lower mold cavity (41) for the molten metal to fill the mold cavity (5) and then flow into it. 4. A die-casting mold for the production of reducer gears according to claim 3, characterized in that: the lower core (4) is provided with a solution guide groove towards the side wall of the upper core (3) (43), the solution guide groove (43) communicates with each of the lower cavities (41), the solution guide groove (43) includes a first flow channel (431) and a second flow channel (432), the A buffer arc surface (433) is provided on the inner wall of the connection between the first flow channel (431) and the second flow channel (432). 5. A die-casting mold for the production of reducer gears according to claim 4, characterized in that: a communication groove is opened between the solution guide groove (43) and each of the lower cavities (41) (411), the groove bottom of the communication groove (411) is inclined upward, the bottom side wall of the notch close to the communication groove (411) is the lowest end, and the communication groove ( 411) The notch close to the lower cavity (41) is the highest end. 6. A die-casting mold for the production of reducer gears according to claim 4, characterized in that: the side wall of the lower core (4) facing the upper core (3) is provided with a plurality of A first exhaust groove (45), a plurality of the first exhaust grooves (45) communicate the solution guide groove (43) with the outside air. 7. A die-casting mold for the production of reducer gears according to claim 3, characterized in that: the side wall of the lower core (4) facing the upper core (3) is provided with a plurality of first Two exhaust grooves (46), a plurality of second exhaust grooves (46) communicate the overflow groove (44) with the outside air. 8. A die-casting mold for the production of reducer gears according to claim 2, characterized in that: the lower core (4) is provided with a plurality of positioning rods (47), and the upper core ( 3) Positioning holes (33) are opened towards the side wall of the lower core (4), the number of the positioning holes (33) corresponds to the number of the positioning rods (47) one by one, the positioning holes (33) For the insertion of the positioning rod (47), when the positioning rod (47) is inserted into the positioning hole (33), the grooves of the upper cavity (31) and the lower cavity (41) The mouths are aligned with each other.

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