CN114908241A

CN114908241A - Mesh belt type protective atmosphere heat treatment equipment based on Aiot technology and preparation method thereof

Info

Publication number: CN114908241A
Application number: CN202210627937.6A
Authority: CN
Inventors: 金燕; 简云娣
Original assignee: Zhenjiang Jinning Technology Co ltd
Current assignee: Zhenjiang Jinning Technology Co ltd
Priority date: 2022-06-02
Filing date: 2022-06-02
Publication date: 2022-08-16

Abstract

The invention relates to the mesh belt type heat treatment equipment field, in particular to mesh belt type heat treatment equipment of protective atmosphere based on Aiot technology, which comprises the following components: the furnace body is provided with a blanking port at the bottom; the device comprises a blanking hopper, wherein the top of the blanking hopper is provided with an insertion plate, the surface of the insertion plate is provided with a stress plate, the surface of the blanking hopper is provided with a first fixed plate, the wall of the blanking hopper is internally inserted with the insertion plate, the top of the insertion plate is provided with a pushing arc plate, the bottom of the blanking hopper is provided with a movable plate, and the end part of the movable plate is provided with a limit plate; the invention also discloses a preparation method of mesh belt type protective atmosphere heat treatment equipment based on the Aiot technology, which comprises the following steps: pre-fixing, disassembling and limiting; the beneficial effects are that: through adding the blanking fill, the blanking fill comprises heat-resisting material, when pegging graft the plugboard in the blanking mouth, the inner wall of blanking mouth can extrude the atress board for the atress board is received inside the plugboard.

Description

Mesh belt type protective atmosphere heat treatment equipment based on Aiot technology and preparation method thereof

Technical Field

The invention relates to the field of mesh belt type heat treatment equipment, in particular to mesh belt type protective atmosphere heat treatment equipment based on an Aiot technology and a preparation method thereof.

Background

The AIoT (artificial intelligence internet of things) is AI (artificial intelligence) + IoT (internet of things), the AIoT integrates AI technology and IoT technology, massive data from different dimensions are generated and collected through the internet of things and stored at a cloud end and an edge end, and then through big data analysis and artificial intelligence of a higher form, all-things datamation and all-things intelligent association are achieved;

mesh belt furnaces are generally sintering furnaces in which a muffle-protected mesh belt conveys parts continuously in the furnace. The method is mainly used for sintering powder metallurgy products, reducing metal powder and pre-sintering, sintering or heat treatment of electronic products in protective atmosphere or air;

among the prior art, mesh belt formula protective atmosphere's equipment for heat treatment's blanking fill can be because high temperature produces the deformation under long-term the use for the product is blocked in the blanking fill, makes the product be heated the time overlength and leads to the product to damage, and the screw rod that is used for fixed blanking fill can expand under being heated, increases the degree of difficulty of dismantling the blanking fill.

Disclosure of Invention

The invention aims to provide mesh belt type protective atmosphere heat treatment equipment based on the Aiot technology and a preparation method thereof, so as to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: mesh belt type protective atmosphere heat treatment equipment based on Aiot technology comprises:

the furnace body is provided with a blanking port at the bottom;

the top of the blanking hopper is provided with an insertion plate, the surface of the insertion plate is provided with a stress plate, the surface of the blanking hopper is provided with a first fixed plate, the wall of the blanking hopper is inserted with the insertion plate, the top of the insertion plate is provided with a pushing arc plate, the bottom of the blanking hopper is provided with a movable plate, and the end part of the movable plate is provided with a limit plate; and

the first screw rod is arranged inside the first fixing plate.

Preferably, the blanking port is rectangular, threaded holes are formed in the bottom of the furnace body, the threaded holes are symmetrically distributed in the two sides of the blanking port, the section shape of the blanking port is identical to that of the insertion plate in size, and the insertion plate can be inserted into the blanking port.

Preferably, the surface of the plugboard is provided with a groove, the groove is inserted with a retractable plate, the top of the retractable plate is provided with a stress plate, the top of one side of the stress plate is arc-shaped, the surface of the stress plate is connected with a first spring, and the other end of the first spring is connected with the inner wall of the surface groove of the plugboard.

Preferably, the bottom of expansion plate is provided with the arc, and the surface of expansion plate is hugged closely to one side of arc, and the opposite side is the arc, and the top of plugboard is located the bottom of arc, and the top of plugboard is installed and is pushed away the arc, and the top that pushes away the arc is the arc, and pushes away the top of arc and laminate in the bottom of arc, and the top that pushes away the arc is provided with the multiunit ball.

Preferably, the bottom of the insertion plate extends out of the bottom of the blanking hopper, the insertion groove is formed in the bottom of the insertion plate, the limiting plate can be inserted into the insertion groove, the moving plate can move at the bottom of the blanking hopper, the limiting plate moves along with the moving plate, and the limiting plate moves in the insertion groove.

Preferably, the second fixing plate is installed at the top of the moving plate and clamped in a groove in the surface of the blanking hopper, a second screw is screwed on the surface of the second fixing plate, a ring groove is formed in the surface of the second screw, and a rotating ring is arranged in the ring groove and can rotate in the ring groove.

Preferably, the surface of swivel becket is provided with the connecting rod, and the connecting rod has two sets ofly, and the tip of connecting rod is installed and is prevented the pole that falls, prevents that the pole that falls pegs graft in the inside of blanking fill, and prevents that the length of falling is longer.

Preferably, the surface of the first fixing plate is provided with a threaded hole, the threaded hole in the surface of the first fixing plate corresponds to the threaded hole in the bottom of the furnace body, the top of the first screw rod is provided with a sliding groove, and the sliding groove is internally provided with an insertion rod which can move in the sliding groove.

Preferably, the top of the insertion rod is provided with a half screw, the surface of the half screw is provided with a telescopic rod, the telescopic rod is inserted in the half screw and can move in the half screw, the surface of the telescopic rod is provided with a second spring, and two ends of the second spring are respectively connected with the surface of the half screw.

The preparation method of the mesh belt type protective atmosphere heat treatment equipment based on the Aiot technology comprises the following steps:

step 1: pre-fixing, namely inserting the insertion plate into the blanking port, compressing the stress plate, allowing the expansion plate to enter the insertion plate, allowing the insertion plate to enter the furnace body, allowing the stress plate to be clamped at the top of the blanking port under the pushing of the first spring after the insertion plate enters the furnace body, and pre-fixing the insertion plate at the bottom of the furnace body;

step 2: fixing, namely, screwing a first screw rod into a first fixing plate, fixing a blanking hopper at the bottom of a furnace body, wherein when the first screw rod is heated, the distance between the half screw rods is reduced, the telescopic rod enters the half screw rods, the inserting rod moves in the sliding groove, and the second spring is compressed;

and step 3: disassembling, namely pushing the inserting plate upwards, pushing the arc-shaped plate by the pushing arc-shaped plate, enabling the expansion plate to enter the inserting plate after the arc-shaped plate is pushed by an upward force, enabling the stress plate not to be clamped at the top of the blanking port, and taking the inserting plate down from the blanking port, wherein in the process of pushing the arc-shaped plate by the pushing arc-shaped plate, the ball at the top of the pushing arc-shaped plate reduces the friction force between the pushing arc-shaped plate and the arc-shaped plate;

and 4, step 4: when the limiting plate is taken out of the insertion groove, the anti-falling rod is still inserted in the blanking hopper, the movable plate is prevented from falling off, and the movable plate can be kept on the surface of the blanking hopper all the time.

Compared with the prior art, the invention has the beneficial effects that:

by adding the blanking hopper which is made of heat-resistant materials, when the insertion plate is inserted into the blanking port, the inner wall of the blanking port can extrude the stress plate to enable the stress plate to be retracted into the insertion plate, then the insertion plate is pre-fixed in the blanking port under the pushing of the first spring after the stress plate enters the furnace body, then the first screw rod penetrates through the screw hole on the surface of the first fixing plate to fix the blanking hopper at the bottom of the furnace body, the top of the first screw rod is made up of two groups of half screw rods, when the half screw rods are heated, the half screw rods can be close to each other to compress the second spring, the telescopic rod is retracted into the half screw rods, when the blanking hopper is required to be disassembled, the insertion plate is pushed upwards to push the pushing arc-shaped plate to enable the telescopic plate to be retracted into the insertion plate, the insertion plate can be removed, and when the insertion plate is not used, the limiting plate is inserted into the insertion groove to prevent the insertion plate from moving, and when the moving plate is pulled out, the anti-falling rod is located inside the blanking hopper to prevent the moving plate from falling.

Drawings

FIG. 1 is a schematic perspective view of the present invention;

FIG. 2 is a schematic perspective view of a first screw of the present invention;

FIG. 3 is a schematic cross-sectional perspective view of a first screw according to the present invention;

FIG. 4 is a schematic perspective view of the blanking hopper of the present invention;

FIG. 5 is a perspective view of the retractable plate of the present invention;

FIG. 6 is a schematic perspective view of a patch panel according to the present invention;

FIG. 7 is a schematic perspective view of a movable plate according to the present invention;

fig. 8 is an enlarged view of a structure shown in fig. 3.

In the figure: the furnace body 1, blanking mouth 2, plugboard 3, blanking fill 4, first screw 5, half screw 6, atress board 7, first fixed plate 8, expansion plate 9, arc 10, first spring 11, top pushes away arc 12, ball 13, plugboard 14, inserting groove 15, limiting plate 16, movable plate 17, connecting rod 18, swivel ring 19, annular 20, second screw 21, prevent the pole 22 that falls, second fixed plate 23, inserted bar 24, spout 25, telescopic link 26, second spring 27.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clear and fully described, embodiments of the present invention are further described in detail below with reference to the accompanying drawings. It is to be understood that the specific embodiments described herein are merely illustrative of some embodiments of the invention and are not limiting of the invention, and that all other embodiments obtained by those of ordinary skill in the art without the exercise of inventive faculty are within the scope of the invention.

In the description of the present invention, it should be noted that the terms "center", "middle", "upper", "lower", "left", "right", "inner", "outer", "top", "bottom", "side", "vertical", "horizontal", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "a," "an," "first," "second," "third," "fourth," "fifth," and "sixth" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

For the purposes of simplicity and explanation, the principles of the embodiments are described by referring mainly to examples. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one skilled in the art that the embodiments may be practiced without these specific details. In some instances, well-known methods and structures have not been described in detail so as not to unnecessarily obscure the embodiments. In addition, all embodiments may be used in combination with each other.

Referring to fig. 1-8, the present invention provides a technical solution: the mesh belt type protective atmosphere heat treatment equipment based on the Aiot technology comprises: the furnace body 1, the bottom of the furnace body 1 is provided with a blanking port 2, the blanking port 2 is rectangular, the bottom of the furnace body 1 is provided with threaded holes, the threaded holes are four groups and are symmetrically distributed on two sides of the blanking port 2, the section shape of the blanking port 2 is consistent with the section shape of the plugboard 3, the plugboard 3 can be inserted into the blanking port 2, the surface of the plugboard 3 is provided with a groove, a telescopic board 9 is inserted in the groove, the top of the telescopic board 9 is provided with a stress board 7, the top of one side of the stress board 7 is arc-shaped, the surface of the stress board 7 is connected with a first spring 11, the other end of the first spring 11 is connected with the inner wall of the surface groove of the plugboard 3, the bottom of the telescopic board 9 is provided with an arc-shaped board 10, one side of the arc-shaped board 10 is tightly attached to the surface of the telescopic board 9, the other side is arc-shaped, the top of the plugboard 14 is positioned at the bottom of the arc-shaped board 10, and the top of the plugboard 14 is provided with a pushing arc-shaped board 12, the top of the pushing arc plate 12 is arc-shaped, the top of the pushing arc plate 12 is attached to the bottom of the arc plate 10, and a plurality of groups of balls 13 are arranged at the top of the pushing arc plate 12;

a blanking hopper 4, an inserting plate 3 is arranged at the top of the blanking hopper 4, a stress plate 7 is arranged on the surface of the inserting plate 3, a first fixing plate 8 is arranged on the surface of the blanking hopper 4, an inserting plate 14 is inserted into the wall of the blanking hopper 4, a pushing arc plate 12 is arranged at the top of the inserting plate 14, a moving plate 17 is arranged at the bottom of the blanking hopper 4, a limiting plate 16 is arranged at the end part of the moving plate 17, the bottom of the inserting plate 14 extends out of the bottom of the blanking hopper 4, an inserting groove 15 is formed in the bottom of the inserting plate 14, the limiting plate 16 can be inserted into the inserting groove 15, the moving plate 17 can move at the bottom of the blanking hopper 4, the limiting plate 16 moves along with the moving plate 17, the limiting plate 16 moves in the inserting groove 15, a second fixing plate 23 is arranged at the top of the moving plate 17, the second fixing plate 23 is clamped in the groove on the surface of the blanking hopper 4, a second screw 21 is screwed on the surface of the second fixing plate 23, a ring groove 20 is formed in the surface of the second screw 21, the ring groove 20 is internally provided with a rotating ring 19, the rotating ring 19 can rotate in the ring groove 20, the surface of the rotating ring 19 is provided with two groups of connecting rods 18, the end parts of the connecting rods 18 are provided with anti-falling rods 22, the anti-falling rods 22 are inserted in the blanking hopper 4, and the anti-falling rods 22 are longer in length;

the first screw 5 is arranged inside the first fixing plate 8, a threaded hole is formed in the surface of the first fixing plate 8, the threaded hole in the surface of the first fixing plate 8 corresponds to a threaded hole in the bottom of the furnace body 1, a sliding groove 25 is formed in the top of the first screw 5, an inserting rod 24 is arranged in the sliding groove 25, the inserting rod 24 can move in the sliding groove 25, a half screw 6 is mounted at the top of the inserting rod 24, a telescopic rod 26 is arranged on the surface of the half screw 6, the telescopic rod 26 is inserted in the half screw 6 and can move in the half screw 6, a second spring 27 is arranged on the surface of the telescopic rod 26, and two ends of the second spring 27 are respectively connected with the surface of the half screw 6;

step 1: pre-fixing, namely inserting the insertion plate 3 into the blanking port 2, compressing the stress plate 7, inserting the expansion plate 9 into the insertion plate 3, inserting the insertion plate 3 into the furnace body 1, then clamping the stress plate 7 on the top of the blanking port 2 under the pushing action of the first spring 11, and pre-fixing the insertion plate 3 at the bottom of the furnace body 1;

step 2: fixing, namely screwing a first screw 5 into a first fixing plate 8, fixing a blanking hopper 4 at the bottom of the furnace body 1, wherein when the first screw 5 is heated, the distance between the half screws 6 is reduced, a telescopic rod 26 enters the half screws 6, a plug rod 24 moves in a sliding groove 25, and a second spring 27 is compressed;

and step 3: disassembling, namely pushing up the inserting plate 14, pushing the arc-shaped plate 10 by the pushing arc-shaped plate 12, enabling the expansion plate 9 to enter the inserting plate 3 after the arc-shaped plate 10 is pushed by an upward force, enabling the stress plate 7 not to be clamped at the top of the blanking port 2, taking down the inserting plate 3 from the blanking port 2, and reducing the friction force between the pushing arc-shaped plate 12 and the arc-shaped plate 10 by the balls 13 at the top of the pushing arc-shaped plate 12 in the process of pushing the arc-shaped plate 10 by the pushing arc-shaped plate 12;

and 4, step 4: when the inserting plate 14 is not used, the limiting plate 16 is inserted into the inserting groove 15, the inserting plate 14 is prevented from moving, when the limiting plate 16 needs to be taken out, the second screw 21 is screwed, so that the moving plate 17 moves, the falling prevention rod 22 is always positioned inside the blanking hopper 4 and plays a role in supporting the moving plate 17, when the limiting plate 16 is taken out of the inserting groove 15, the falling prevention rod 22 is also inserted into the blanking hopper 4, the moving plate 17 is prevented from falling, and the moving plate 17 can be always kept on the surface of the blanking hopper 4.

When the inserting plate 3 is inserted into the blanking port 2, the inner wall of the blanking port 2 extrudes the stress plate 7, so that the stress plate 7 is retracted into the inserting plate 3, then the inserting plate 3 is pre-fixed in the blanking port 2 under the pushing of the first spring 11 after the stress plate 7 enters the furnace body 1, then the first screw 5 penetrates through the screw hole on the surface of the first fixing plate 8, the blanking hopper 4 is fixed at the bottom of the furnace body 1, the blanking hopper 4 is made of heat-resistant material, the situation that the blanking hopper 4 is deformed by heat can be solved, the top of the first screw 5 is composed of two groups of half screws 6, when the half screws 6 are heated, the half screws 6 can approach each other, the second spring 27 is compressed, the expansion rod 26 is retracted into the half screws 6, when the blanking hopper 4 is dismounted, the first screw 5 cannot be dismounted due to thermal expansion, when the blanking hopper 4 needs to be dismounted, the inserting plate 14 is pushed upwards, the pushing arc plate 12 supports the arc plate 10, the inserting plate 3 can be taken down by retracting the expansion plate 9 into the inserting plate 3, the limiting plate 16 is inserted into the inserting groove 15 when the inserting plate 14 is not used, the inserting plate 14 is prevented from moving, and the falling-preventing rod 22 is positioned in the falling hopper 4 when the moving plate 17 is pulled out, so that the moving plate 17 is prevented from falling.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. Mesh belt type protective atmosphere heat treatment equipment based on Aiot technology is characterized in that: the method comprises the following steps:

the furnace comprises a furnace body (1), wherein the bottom of the furnace body (1) is provided with a blanking port (2);

the device comprises a blanking hopper (4), wherein an insertion plate (3) is arranged at the top of the blanking hopper (4), a stress plate (7) is arranged on the surface of the insertion plate (3), a first fixing plate (8) is arranged on the surface of the blanking hopper (4), an insertion plate (14) is inserted into the wall of the blanking hopper (4), a pushing arc plate (12) is arranged at the top of the insertion plate (14), a moving plate (17) is arranged at the bottom of the blanking hopper (4), and a limiting plate (16) is arranged at the end part of the moving plate (17); and

the first screw (5) is arranged inside the first fixing plate (8).

2. The Aiot technology based mesh-belt protective atmosphere heat treatment apparatus of claim 1, wherein: the furnace body is characterized in that the blanking port (2) is rectangular, threaded holes are formed in the bottom of the furnace body (1), the threaded holes are provided with four groups and symmetrically distributed on two sides of the blanking port (2), the section shape of the blanking port (2) is consistent with that of the insertion plate (3), and the insertion plate (3) can be inserted into the blanking port (2).

3. The Aiot technology based mesh-belt protective atmosphere heat treatment apparatus of claim 2, wherein: the surface of the plugboard (3) is provided with a groove, the expansion board (9) is inserted in the groove, the top of the expansion board (9) is provided with a stress board (7), the top of one side of the stress board (7) is arc-shaped, the surface of the stress board (7) is connected with a first spring (11), and the other end of the first spring (11) is connected with the inner wall of the surface groove of the plugboard (3).

4. The Aiot technology-based mesh-belt type protective atmosphere heat treatment apparatus according to claim 3, wherein: the bottom of expansion plate (9) is provided with arc (10), and the surface of expansion plate (9) is hugged closely to one side of arc (10), and the opposite side is the arc, and the top of plugboard (14) is located the bottom of arc (10), and top push arc (12) are installed at the top of plugboard (14), and the top that pushes up arc (12) is the arc, and pushes up the top of arc (12) and laminate in the bottom of arc (10), and the top that pushes up arc (12) is provided with multiunit ball (13).

5. The Aiot technology-based mesh-belt type protective atmosphere heat treatment apparatus according to claim 4, wherein: the bottom of plugboard (14) stretches out the bottom of blanking fill (4), and inserting groove (15) have been seted up to the bottom of plugboard (14), and limiting plate (16) can peg graft in inserting groove (15), and movable plate (17) can move in the bottom of blanking fill (4), and limiting plate (16) are following movable plate (17) and are moving, and limiting plate (16) move in inserting groove (15).

6. The Aiot technology-based mesh-belt type protective atmosphere heat treatment apparatus according to claim 5, wherein: the top of the moving plate (17) is provided with a second fixing plate (23), the second fixing plate (23) is clamped in a groove in the surface of the blanking hopper (4), the surface of the second fixing plate (23) is in threaded connection with a second screw (21), a ring groove (20) is formed in the surface of the second screw (21), a rotating ring (19) is arranged in the ring groove (20), and the rotating ring (19) can rotate in the ring groove (20).

7. The Aiot technology-based mesh-belt type protective atmosphere heat treatment apparatus according to claim 6, wherein: the surface of the rotating ring (19) is provided with two groups of connecting rods (18), the end parts of the connecting rods (18) are provided with anti-falling rods (22), the anti-falling rods (22) are inserted in the blanking hopper (4), and the anti-falling rods (22) are longer in length.

8. The Aiot technology-based mesh-belt type protective atmosphere heat treatment apparatus according to claim 7, wherein: the surface of the first fixing plate (8) is provided with a threaded hole, the threaded hole in the surface of the first fixing plate (8) corresponds to the threaded hole in the bottom of the furnace body (1), the top of the first screw (5) is provided with a sliding groove (25), the sliding groove (25) is internally provided with an inserting rod (24), and the inserting rod (24) can move in the sliding groove (25).

9. The Aiot technology-based mesh-belt type protective atmosphere heat treatment apparatus according to claim 8, wherein: half screw rod (6) are installed at the top of grafting pole (24), and the surface of half screw rod (6) is provided with telescopic link (26), and telescopic link (26) are pegged graft in half screw rod (6) and can be removed in half screw rod (6), and the surface of telescopic link (26) is provided with second spring (27), and the surface of half screw rod (6) is respectively being connected at the both ends of second spring (27).

10. A method for preparing the mesh-belt type protective atmosphere heat treatment equipment based on the Aiot technology according to any one of claims 1 to 9, characterized in that: the processing flow of the product comprises the following steps:

step 1: pre-fixing, namely inserting the insertion plate (3) into the blanking port (2), compressing the stress plate (7), allowing the expansion plate (9) to enter the insertion plate (3), allowing the insertion plate (3) to enter the furnace body (1), clamping the stress plate (7) at the top of the blanking port (2) under the pushing of the first spring (11), and pre-fixing the insertion plate (3) at the bottom of the furnace body (1);

step 2: fixing, namely connecting a first screw (5) in a first fixing plate (8) in a screwed mode, fixing a blanking hopper (4) at the bottom of a furnace body (1), wherein when the first screw (5) is heated, the distance between half screws (6) is reduced, a telescopic rod (26) enters the half screws (6), an inserting rod (24) moves in a sliding groove (25), and a second spring (27) is compressed;

and step 3: disassembling, namely pushing up the inserting plate (14), pushing the arc-shaped plate (10) by the pushing arc plate (12), pushing the arc-shaped plate (10) by an upward force, making the expansion plate (9) enter the inserting plate (3), making the stress plate (7) not clamped at the top of the blanking port (2), taking the inserting plate (3) down from the blanking port (2), and reducing the friction force between the pushing arc plate (12) and the arc-shaped plate (10) by the balls (13) at the top of the pushing arc plate (12) in the process of pushing the arc-shaped plate (12);

and 4, step 4: the limiting plate (16) is inserted into the insertion groove (15) when the insertion plate (14) is not used, the insertion plate (14) is prevented from moving, when the limiting plate (16) needs to be taken out, the second screw (21) is screwed, the moving plate (17) moves, the falling prevention rod (22) is located inside the falling hopper (4) all the time, the effect of supporting the moving plate (17) is achieved, when the limiting plate (16) is taken out of the insertion groove (15), the falling prevention rod (22) is further inserted into the falling hopper (4), the moving plate (17) is prevented from falling, and the moving plate (17) can be kept on the surface of the falling hopper (4) all the time.