Dredging device and dredging method for sand shooting nozzle of core box

Abstract

The invention provides a core box sand shooting nozzle dredging device and a dredging method thereof, and relates to the technical field of casting core-making devices.The core box sand shooting nozzle dredging device is characterized in that a positioning block is attached to a sand shooting hole formed in a lower mold plate, a reset spring is arranged at the top of the positioning block, a base is fixedly connected to the side, away from the positioning block, of the reset spring, and a handle is fixedly connected to the base in the transverse direction; the cylinder assembly is arranged at the top of the base, the ejector pin is arranged on a piston rod at the top end of the cylinder assembly, and the ejector pin is inserted into the sand-shooting nozzle, so that the technical problems that the sand-shooting nozzle which is seriously caked cannot be quickly dredged and the working time is prolonged due to manual fine iron drill rod dredging are solved, and the purposes of quickly dredging, reducing personnel labor and improving the working efficiency are achieved. And the structure of the mold is not changed.

Description

Technical Field

[0001] The invention relates to the technical field of casting core making devices, in particular to a dredging device for a core box sand shooting nozzle and a dredging method thereof. Background Art

[0002] In foundry production, the core box mold is a key tool for producing sand cores, and the sand-shooting nozzle is the component that enables sand filling within the core box mold. During the sand-shooting process, the nozzle passes through the holes in the upper mold plate and injects sand into the hollow cavity within the core box to complete the filling process. Since the normal operating temperature of the upper and lower mold plates and the mold cavity is approximately 200°C, the temperature of the sand-shooting nozzle will continue to rise during continuous production. Any sand remaining in the nozzle will agglomerate due to the increased temperature, leading to nozzle blockage.

[0003] When a sandblasting nozzle is clogged, the existing method of unclogging it is for the operator to shut down the machine and perform the operation. The specific operation steps are as follows: first, the power supply of the equipment needs to be turned off, then the upper template is removed, and the operator enters the equipment and uses a fine iron rod tool to unblock the clogged sandblasting nozzle.

[0004] Existing technology uses manual unclogging with a fine iron rod. If the agglomeration is severe, repeated manual vertical movement is required, increasing the working time. Furthermore, frequent shutdowns, power outages, removal of the upper template, and personnel entering the equipment to operate the equipment greatly increase the difficulty of operation. Furthermore, entering the equipment to operate the equipment also poses certain safety risks. Summary of the Invention

[0005] The purpose of the present invention is to provide a core box sand shooting nozzle dredging device to alleviate the technical problems existing in the prior art of manual fine iron rod dredging, which cannot quickly dredge the sand shooting nozzle with serious agglomeration and increases the working time.

[0006] Another object of the present invention is to provide a method for unclogging a core box sand-shooting nozzle.

[0007] The present invention provides a core box sand shooting nozzle dredging device, comprising: an upper template, a lower template, a sand shooting hole and a sand shooting nozzle; the upper template and the lower template are arranged opposite to each other, and both the upper template and the lower template are provided with a sand shooting hole for shooting sand into the hollow cavity in the core box, and the sand shooting nozzle is attached to the sand shooting hole provided on the upper template; The sand shooting hole opened on the lower template is fitted with a positioning block, a reset spring is provided on the top of the positioning block, a base is fixedly connected to the side of the reset spring facing away from the positioning block, a handle is fixedly connected to the base along the horizontal direction, a cylinder assembly is provided on the top of the base, and a thimble is provided on the top piston rod of the cylinder assembly, and the thimble is inserted into the sand shooting nozzle.

[0008] Furthermore, the positioning block includes a locking portion and a rectangular portion; The clamping portion is in a frustum shape and is clamped into the sand-shooting hole on the lower template.

[0009] Furthermore, a connecting block is provided at the lower portion of the base near the edge, and the connecting block is connected to the handle via a horizontally arranged connecting rod.

[0010] Furthermore, the cylinder assembly includes a cylinder body, a piston rod, an air pipe and a pneumatic switch; The cylinder body is arranged on the top of the base, the end of the telescopic piston rod at the top of the cylinder body is welded to the ejector pin, the cylinder body is connected to the pneumatic switch through the air pipe, and the pneumatic switch is arranged on the connecting rod near the handle.

[0011] Furthermore, the pneumatic switch is a knob-type pneumatic switch, and the inner diameter of the air pipe is 6 mm to 8 mm.

[0012] Furthermore, the head of the ejector pin is in a pointed cone shape, the tip angle of the ejector pin is 30° to 45°, and the length of the ejector pin is 80 mm to 150 mm.

[0013] Furthermore, the ejector pin is made of aluminum alloy or titanium alloy.

[0014] Furthermore, the free length of the return spring is 50 mm to 200 mm.

[0015] Furthermore, the bottom surface of the locking portion is provided with anti-slip grooves.

[0016] The present invention also provides a method for unclogging a core box sand-shooting nozzle, comprising the following steps: Step 1: Use the handle to move the base between the upper and lower templates, so that the sand shooting holes on the upper and lower templates are in the same longitudinal horizontal plane, so that the reset spring is tightened, the positioning block is inserted into the sand shooting hole of the lower template for positioning, and the top needle is aligned with the sand shooting nozzle; Step 2: The piston rod of the cylinder assembly moves at a speed of 50 mm / s to 100 mm / s, and the ejector pin is inserted into the sand-shooting nozzle to clear the sand-shooting nozzle.

[0017] Beneficial effects: The present invention provides a core box sand shooting nozzle dredging device and a dredging method thereof, comprising a sand shooting hole opened on a lower template and fitted with a positioning block, a reset spring being provided on the top of the positioning block, a base being fixedly connected to the side of the reset spring facing away from the positioning block, a handle being fixedly connected to the base along the horizontal direction, a cylinder assembly being provided on the top piston rod of the cylinder assembly and a thimble being inserted into the sand shooting nozzle.

[0018] The positioning block fits in with the sand-shooting hole of the lower template to locate the sand-shooting nozzle and ensure the accuracy of the dredging operation. The reset spring on the top of the positioning block can be extended and retracted to bring the positioning block out of the sand-shooting hole below. The handle fixed horizontally to the base is convenient for the operator to hold and operate. The piston rod of the cylinder assembly on the top of the base drives the ejector pin to move, which can realize automated dredging operations. The operator does not need to enter the interior of the equipment, and can complete the cleaning of the sandblasting nozzle blockage through the power output of the cylinder assembly from the outside. This not only reduces labor intensity, but also avoids the tedious steps of powering off and disassembling the equipment, effectively improving production efficiency. At the same time, it isolates the operator from the equipment operation area, significantly improving the safety of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 A schematic structural diagram of a core box sand-shooting nozzle dredging device provided in an embodiment of the present invention; Figure 2 A top view of a dredging device for a core box sand shooting nozzle provided in an embodiment of the present invention; Figure 3 A schematic diagram of the working of the dredging device for the core box sand shooting nozzle provided by an embodiment of the present invention; Figure 4 The present invention provides a flowchart of a method for unclogging a core box sandblasting nozzle.

[0021] Icons: 1-upper template; 2-lower template; 3-sand shooting hole; 4-sand shooting nozzle; 5-positioning block; 501-locking part; 502-rectangular part; 6-reset spring; 7-base; 8-handle; 801-connecting block; 802-connecting rod; 9-cylinder assembly; 901-cylinder body; 902-air pipe; 903-pneumatic switch; 10-thimble. DETAILED DESCRIPTION

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0024] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0025] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like indicate positions or locations based on the positions shown in the accompanying drawings, or the positions or locations in which the inventive product is typically placed when in use. These terms are intended solely to facilitate the description of the present invention and to simplify the description, and are not intended to indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0026] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0027] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to mechanical connections or electrical connections; they may refer to direct connections or indirect connections through an intermediate medium; and they may refer to internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0028] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0029] like Figure 1 、 Figure 2 and Figure 3As shown, the present invention provides a core box sand shooting nozzle dredging device, comprising: an upper template 1, a lower template 2, a sand shooting hole 3 and a sand shooting nozzle 4; the upper template 1 and the lower template 2 are arranged opposite to each other, and the upper template 1 and the lower template 2 are both provided with sand shooting holes 3 for sand shooting into the hollow cavity in the core box, and the sand shooting nozzle 4 is fitted into the sand shooting hole 3 provided on the upper template 1.

[0030] The sand-shooting hole 3 opened on the lower template 2 is fitted with a positioning block 5, a return spring 6 is provided on the top of the positioning block 5, a base 7 is fixedly connected to the side of the return spring 6 facing away from the positioning block 5, a handle 8 is fixedly connected to the base 7 along the horizontal direction, a cylinder assembly 9 is provided on the top of the base 7, and a top piston rod of the cylinder assembly 9 is provided with an ejector pin 10, which is inserted into the sand-shooting nozzle 4.

[0031] Specifically, the upper template 1 and the lower template 2 are arranged relatively parallel, and coaxial corresponding sand shooting holes 3 are opened in the middle of both. A sand shooting nozzle 4 is tightly fitted in the sand shooting hole 3 of the upper template 1, and the lower end of the sand shooting nozzle 4 extends into the hollow cavity of the core box for sand shooting operations.

[0032] A positioning block 5 is placed on the outside of the sand shooting hole 3 of the lower template 2 by interference fit. The top of the positioning block 5 is fixedly connected to the lower end of the return spring 6. The upper end of the return spring 6 is fixed to the center of the bottom surface of the base 7 by welding. The base 7 is provided with a handle 8 along the horizontal transverse direction. The cylinder assembly 9 is rigidly mounted on the top of the base 7 by bolts. The top piston rod of the cylinder assembly 9 is screwed to the ejector pin 10 by threading. The ejector pin 10 is coaxially inserted into the sand shooting nozzle 4 through the sand shooting hole 3 of the lower template 2 and the sand shooting hole 3 of the upper template 1.

[0033] The engagement of the positioning block 5 and the sand-shooting hole 3 of the lower template 2 can realize the precise positioning of the tool and the mold, ensuring the coaxiality of the axis of the ejector pin 10 and the sand-shooting nozzle 4; the reset spring 6 can provide a buffering force during the unblocking operation of the ejector pin 10 to avoid damage to the mold by rigid impact, and also facilitate the engagement of the positioning block 5 and the sand-shooting hole 3, and facilitate the delivery and removal of the unblocking device of the core box sand-shooting nozzle; the horizontal handle 8 is convenient for the operator to hold and adjust the position of the tool; the cylinder assembly 9 pneumatically drives the ejector pin 10 to move back and forth longitudinally, so that the operator does not need to enter the interior of the equipment, and can complete the unblocking of the sand-shooting nozzle 4 through the handle 8 from the outside, which not only reduces the tedious process of equipment shutdown and power outage and template disassembly, improves production efficiency, but also ensures personnel safety through remote operation. At the same time, the elastic reset function of the reset spring 6 can make the tool automatically detach from the mold after operation, which is convenient for the connection of subsequent processes.

[0034] In an embodiment of the present invention, the positioning block includes a locking portion 501 and a rectangular portion 502 ; the locking portion 501 is in a frustum shape, and the locking portion 501 is locked into the sand-shooting hole 3 on the lower template 2 .

[0035] A connecting block 801 is provided at the lower portion of the base 7 near the edge, and the connecting block 801 is connected to the handle 8 via a horizontally arranged connecting rod 802 .

[0036] The cylinder assembly 9 includes a cylinder body 901, an air pipe 902 and a pneumatic switch 903; The cylinder body 901 is arranged on the top of the base 7, and the end of the telescopic piston rod at the top of the cylinder body 901 is welded to the ejector pin 10. The cylinder body 901 is connected to the pneumatic switch 903 through the air pipe 902. The pneumatic switch 903 is arranged on the connecting rod 802 near the handle 8.

[0037] The pneumatic switch 903 is a knob-type pneumatic switch, and the inner diameter of the air pipe 902 is 6 mm to 8 mm, preferably 7 mm.

[0038] Specifically, the positioning block 5 is composed of an integrally formed locking portion 501 and a rectangular portion 502. The locking portion 501 is an inverted frustum-shaped structure, and the locking portion 501 is locked into the sand-shooting hole 3 of the lower template 2 to achieve positioning with the mold; the rectangular portion 502 is located above the locking portion 501, and its side length is larger than the bottom diameter of the locking portion 501, and the height is 15 to 20 mm. A blind hole is opened in the center of the top surface of the rectangular portion 502 for embedding the lower end of the reset spring 6.

[0039] The base 7 is a square plate-like structure, and the center of its bottom surface is fixedly connected to the upper end of the reset spring 6 by welding. A connecting block 801 is welded at the edge of the lower part of the base 7. The connecting block 801 is a cube structure, and a horizontal through hole is opened in the middle of the connecting block 801 for passing the connecting rod 802.

[0040] The handle 8 is a circular tubular structure, and the connecting rod 802 is made of round steel. The outer end of the connecting rod 802 is connected to the handle 8 through an external thread, and the inner end is locked in the through hole of the connecting block 801.

[0041] The cylinder body 901 of the cylinder assembly 9 adopts a standard cylinder. The cylinder body 901 is fixedly connected to the top surface of the base 7 through a bottom flange with four bolts. The end of the piston rod of the cylinder body 901 is provided with an external thread, which is screwed to the internal thread hole opened at the tail of the ejector pin 10 and then reinforced by welding to ensure the connection strength.

[0042] The air pipe 902 is a PU hose, one end of which is connected to the air inlet of the cylinder body 901 through a quick-connect connector, and the other end is connected to the air outlet of the pneumatic switch 903; The interference fit between the frustum-shaped positioning portion 501 and the sand-shooting hole 3 enables quick and accurate positioning of the tool, ensuring that the coaxiality error between the ejector pin 10 and the sand-shooting nozzle 4 does not exceed 0.5 mm; the inner diameter of the air pipe 902 ensures the response speed of the cylinder body 901; the position of the knob-type pneumatic switch 903 allows the operator to complete the tool positioning and unblocking operations with one hand, reducing labor intensity while improving the unblocking efficiency of the sand-shooting nozzle 4, and the buffering effect of the return spring 6 can control the vibration amplitude during operation, effectively protecting the service life of the mold and tool.

[0043] It should be noted that the locking portion 501 may also be semicircular or in other shapes so as to be able to be locked into the sand-shooting hole 3 on the lower template 2 .

[0044] In an embodiment of the present invention, the head of the ejector pin 10 is in a pointed cone shape, and the tip angle of the ejector pin 10 is 30° to 45°, preferably 30°. The length of the ejector pin is 80 mm to 150 mm, preferably 100 mm.

[0045] The material of the ejector pin 10 is aluminum alloy or titanium alloy.

[0046] The free length of the return spring 6 is 50 mm to 200 mm, preferably 200 mm.

[0047] The bottom surface of the locking portion 501 is provided with anti-slip grooves.

[0048] Specifically, the tip of ejector pin 10 is a pointed cone with a 30° angle. This ensures that ejector pin 10 can effectively cut and break blockages within the sandblasting nozzle 4 while minimizing contact with sand particles, lowering friction and facilitating smoother unblocking operations. The overall length of ejector pin 10 is 100 mm, ensuring it can penetrate deep into the sandblasting nozzle 4 to clear the blockage while avoiding bending deformation caused by insufficient rigidity due to its length, ensuring that the cylinder assembly 9 can effectively reach the blockage.

[0049] The free length of the return spring 6 is 200 mm. Under the action of the gravity of the cylinder assembly 9 and the ejector pin 10, the return spring 6 can provide a stable elastic supporting force to ensure that the positioning block 5 fits tightly with the sand-shooting hole 3 of the lower template 2, and effectively buffer the impact force during the dredging operation of the ejector pin 10.

[0050] The bottom surface of the locking portion 501 is processed with diamond-shaped anti-slip grooves with a depth of 0.5 mm, which can effectively prevent the positioning block 5 from sliding during tool operation and ensure that the coaxiality of the ejector pin 10 and the sandblasting nozzle 4 remains unchanged.

[0051] The tip angle and length of the ejector pin 10 are coordinated to improve its efficiency in dredging operations compared to traditional manual thin iron picks; the return spring 6 ensures the overall stability and buffering performance of the tool, reducing damage to the mold; the anti-slip grooves on the bottom surface of the locking portion 501 further improve the anti-slip performance.

[0052] like Figure 4 As shown, the present invention provides a method for unclogging a core box sand shooting nozzle, which uses the above-mentioned unclogging device for the core box sand shooting nozzle and includes the following steps: Step 1: Use the handle 8 to move the base 7 between the upper template 1 and the lower template 2, so that the sand shooting holes 3 on the upper template 1 and the lower template 2 are in the same longitudinal horizontal plane, so that the return spring 6 is tightened, the positioning block 5 is snapped into the sand shooting hole 3 of the lower template 2 for positioning, and the ejector pin 10 is aligned with the sand shooting nozzle 4; Specifically, the operator holds handle 8, maintains the tool in a vertical position, and slowly inserts base 7 into the gap between upper and lower templates 1 and 2. Aligning retaining portion 501 of positioning block 5 with sandblasting hole 3 in lower template 2, the operator slowly applies downward pressure. The frustum of retaining portion 501 guides the tool into sandblasting hole 3, and the return spring 6 begins to compress until the bottom surface of rectangular portion 502 contacts the top surface of lower template 2.

[0053] The axis of the ejector pin 10 coincides with the axis of the sandblasting nozzle 4 .

[0054] Step 2: The piston rod of the cylinder assembly 9 performs piston motion at a speed of 50 mm / s to 100 mm / s, and the ejector pin 10 is inserted into the sand-shooting nozzle 4 to clear the sand-shooting nozzle 4.

[0055] Specifically, the operator rotates the pneumatic switch 903 to the "on" position, and compressed air enters the rodless cavity of the cylinder body 901 through the air pipe 902. The piston rod of the cylinder assembly 9 begins to extend at a set speed, driving the ejector pin 10 to be inserted into the sandblasting nozzle 4.

[0056] The pointed conical head of ejector pin 10 contacts the agglomerated sand particles within the sandblasting nozzle 4, breaking them apart through axial impact force. After reaching maximum travel, pneumatic switch 903 switches to the "return" position, causing the piston rod to retract, driving ejector pin 10 out of the sandblasting nozzle 4. Repeat this process to ensure complete removal of any remaining sand fragments.

[0057] After the dredging is completed, the operator pulls up the handle 8 to overcome the elastic force of the return spring 6, so that the positioning block 5 is separated from the sand-shooting hole 3 of the lower template 2. The tool is moved out of the gap between the upper template 1 and the lower template 2.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A core box sand nozzle dredging device, comprising: An upper template (1), a lower template (2), a sand-shooting hole (3) and a sand-shooting nozzle (4); the upper template (1) and the lower template (2) are arranged relative to each other, and the upper template (1) and the lower template (2) are both provided with the sand-shooting hole (3) for sand-shooting the hollow cavity in the core box, and the sand-shooting nozzle (4) is fitted in the sand-shooting hole (3) provided on the upper template (1), characterized in that: The sand-shooting hole (3) opened on the lower template (2) is fitted with a positioning block (5), a return spring (6) is provided on the top of the positioning block (5), a base (7) is fixedly connected to the side of the return spring (6) facing away from the positioning block (5), a handle (8) is fixedly connected to the base (7) along the horizontal direction, a cylinder assembly (9) is provided on the top of the base (7), a top piston rod of the cylinder assembly (9) is provided with an ejector pin (10), and the ejector pin (10) is inserted into the inside of the sand-shooting nozzle (4).

2. The dredging device for the core box sand shooting nozzle according to claim 1, characterized in that: The positioning block (5) comprises a locking portion (501) and a rectangular portion (502); The locking portion (501) is in the shape of a cone, and the locking portion (501) is locked into the sand-shooting hole (3) on the lower template (2).

3. The dredging device for the core box sand shooting nozzle according to claim 1, characterized in that: A connecting block (801) is provided at the lower portion of the base (7) near the edge, and the connecting block (801) is connected to the handle (8) via a horizontally arranged connecting rod (802).

4. The dredging device for the core box sand shooting nozzle according to claim 3, characterized in that: The cylinder assembly (9) comprises a cylinder body (901), an air pipe (902) and a pneumatic switch (903); The cylinder body (901) is arranged on the top of the base (7), the end of the telescopic piston rod at the top of the cylinder body (901) is welded to the ejector pin (10), the cylinder body (901) is connected to the pneumatic switch (903) through the air pipe (902), and the pneumatic switch (903) is arranged on the connecting rod (802) near the handle (8).

5. The dredging device for the core box sand shooting nozzle according to claim 4, characterized in that: The pneumatic switch (903) is a knob-type pneumatic switch, and the inner diameter of the air pipe (902) is 6 mm to 8 mm.

6. The dredging device for the core box sand shooting nozzle according to claim 1, characterized in that: The head of the ejector pin (10) is in a pointed cone shape, the tip angle of the ejector pin (10) is 30° to 45°, and the length of the ejector pin is 80 mm to 150 mm.

7. The dredging device for the core box sand shooting nozzle according to claim 6, characterized in that: The material of the ejector pin (10) is aluminum alloy or titanium alloy.

8. The dredging device for a core box sand-shooting nozzle according to claim 1, characterized in that: The free length of the return spring (6) is 50 mm to 200 mm.

9. The dredging device for a core box sand-shooting nozzle according to claim 2, characterized in that: The bottom surface of the locking portion (501) is provided with anti-slip grooves.

10. A method for unclogging a core box sand jet nozzle, characterized in that: The method uses the core box sand shooting nozzle dredging device according to any one of claims 1 to 9, comprising the following steps: Step 1: Use the handle (8) to move the base (7) between the upper template (1) and the lower template (2), so that the sand-shooting holes (3) on the upper template (1) and the lower template (2) are in the same longitudinal horizontal plane, so that the return spring (6) is tightened, the positioning block (5) is inserted into the sand-shooting hole (3) of the lower template (2) for positioning, and the ejector pin (10) is aligned with the sand-shooting nozzle (4); Step 2: The piston rod of the cylinder assembly (9) performs piston motion at a speed of 50 mm / s to 100 mm / s, and the ejector pin (10) is inserted into the sand-shooting nozzle (4) to clear the sand-shooting nozzle (4).

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