JPH0217265B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to vertical mold clamping and vertical injection molds in which molten metal or molten resin is injected into the cavity of a vertically clamped mold from directly below the cavity. This invention relates to injection molding equipment.

[Conventional technology]

Injection molding equipment such as die casting machines or injection molding machines for plastics is classified into vertical clamping molds and horizontal clamping molds according to the mold clamping direction, and into vertical injection molds and horizontal injection molds according to the injection direction. be done.

FIG. 6 is a longitudinal sectional view of the main parts of a conventional vertical mold clamping and vertical injection die casting machine. and,
It is equipped with a movable platen 2 that moves up and down along tie rods (not shown) installed at its four corners.
A fixed mold 3 and a movable mold 4 are fixed to both platens 1 and 2, respectively. Furthermore, a pair of cores 5 and 6 are interposed between the upper and lower molds 4 and 3 and are supported by the movable mold 4 side, and are moved forward and backward in the horizontal direction indicated by the symbol A by a drive device (not shown). It is configured. And mold 3 of this example,
4 and cores 5 and 6 are for molding aluminum foil for vehicles, and between the convex portions of the molds 3 and 4 and the half-ring-shaped cores 5 and 6, aluminum foil and A cavity 7, which is a space having the same shape, is formed. On the other hand, below the machine base to which the fixed platen 1 is fixed, an injection cylinder (not shown) is arranged so as to be able to stand up and tilt freely, and 8 is a plunger that moves up and down by this injection cylinder, and 9 is a block that is raised and lowered by another cylinder on the injection cylinder side. An injection sleeve 10 into which a plunger 8 is fitted is fixed concentrically to the upper end of this block 9, and when the block 9 is raised, the injection sleeve 10 is inserted into the fixed mold 3 as shown in the figure. It is fitted into the sleeve hole 3a. Furthermore, the injection sleeve 10 and the block 9 are engaged in the notch 1a of the fixed platen 1, and when the block 9 is lowered, the injection sleeve 10 is pulled out from the sleeve hole 3a, and the entire injection cylinder is shown by arrow B in the figure. The molten metal 11 is injected into the injection sleeve 10 by tilting the injection sleeve 10 in the direction shown in FIG.

With this configuration, as shown in the figure, after the mold is clamped, the injection cylinder is tilted with the block 9 and the injection sleeve 10 being lowered, and the molten metal 11 is injected into the injection sleeve 10.
The injection cylinder is erected, the block 9 is raised, and the injection sleeve 10 is fitted into the sleeve hole 3a. When pressure oil is fed into the injection cylinder to raise the plunger 8, the plunger tip 8a, which is the head of the plunger 8, pushes up the molten metal 11 and injects it into the cavity 7. plunger tip 8
When a rises to the position indicated by the chain line 13 and stops, the filling of the molten metal 11 into the cavity 7 is completed.
After waiting for the molten metal 11 to solidify, the movable platen 2 is raised to open the mold, the cores 5 and 6 are moved outward, and the solidified product is ejected from the cavity 7. In this case, the broken line 12 in the figure is the lower end of the product, and this product includes a solidified molten metal, a so-called biscuit, at a location indicated by the reference numeral 14 between the broken line 12 and the chain line 13, which is the upper limit of the plunger tip 8a. do. This biscuit is cut in a separate process after the product is taken out.

[Problem that the invention seeks to solve]

However, in such conventional vertical mold clamping and vertical injection die casting machines, the diameter of the molten metal passage between the cavity 7 and the injection sleeve 10 is set to be smaller than the inner diameter of the injection sleeve 10 in order to remove the product after opening the mold. Since it cannot be made smaller, the biscuit becomes larger and requires more molten metal, which is not only uneconomical, but also, for example, when the surface of aluminum foil, which is indicated by the broken line 12 in the figure, becomes a decorative surface. Since this becomes the cut surface of the biscuit, there is a problem in that it becomes a rough surface and cannot be designed. In addition, the number 15 in the figure
Shell, which is a solidified molten metal, is often pushed up by the plunger tip 8a during casting and enters the cavity 7, and this shell remains inside the product, degrading the quality of the product. Therefore, conventionally, in order to block the intrusion of the shell 15, the broken line 1
Attempts have been made to provide a wire mesh called punching metal at the location shown in 2 or to fit a ring into the upper end of the inner hole of the injection sleeve 10, but these methods are cumbersome to handle and increase the consumption of consumables. There was a problem.

[Means for solving problems]

In order to solve these problems, the present invention provides a vertical injection molding device with a vertical injection molding device having a cross-sectional area smaller than the inner hole of the injection sleeve in the melt passage between the injection sleeve and the mold cavity. A gate plate having a hole and divided into parts with the center of the hole as a boundary is provided so as to be movable in the horizontal direction, and a regulating member is provided on the gate plate to restrict movement in a direction perpendicular to the direction of movement of the gate plate. They were provided on both sides, and at least one of them was formed to be movable.

[Effect]

When the hole in the gate plate is located at the center of the melt passage and the melt is injected into the cavity, the shell generated in the injection sleeve is blocked by the hole in the gate plate and remains in the injection sleeve. During injection, the movement of the gate plate is restricted by the movement regulating member to cope with the internal stress of the gate plate due to thermal expansion and injection of molten metal. After the molten material filled in the cavity has solidified, the movement restriction of the gate plate by the movement restricting member is released, and both divided gate plates are moved in the same direction. When the mold is opened, the product is held on the movable mold side, leaving the biscuit below the gate plate, and by ejecting it, the injection cycle is completed. When the gate plate moves, it moves smoothly because it is free from the restriction of the movement restriction member in the orthogonal direction. Furthermore, if you do not want to shear the solidified molten metal, perform injection with the gate plate closed, then open the left and right gate plates by moving them in opposite directions, so that the hole in the gate plate is aligned with the hole in the injection sleeve. Since the diameter is small, the product can be ejected without any problem. After taking out the product, remove the biscuit by cutting from the thin part that corresponded to the hole in the gate plate during injection.

〔Example〕

1 to 3 show an example in which the injection molding apparatus according to the present invention is applied to a vertical mold clamping, vertical injection type die casting machine.
The figure is a sectional view CC of FIG. 1, and FIGS. 3 a to 3 f are longitudinal sectional views of main parts shown for explaining the operation. In the figure, the vertical mold clamping and vertical casting die casting machine includes a fixed platen 21 fixed on a machine base (not shown), and a movable platen 22 that moves up and down along tie rods (not shown) installed at its four corners. These platens 21 and 22 are equipped with
A rectangular fixed mold 23 and a movable mold 24 are each fixed. Then, a mold clamping cylinder (not shown) above the movable platen 22 closes the movable platen 2.
By moving the movable metal 24 up and down, the movable metal 24 is clamped to the fixed mold 23 and opened. Further, between the upper and lower molds 24 and 23, a pair of cores 25 and 26 having semi-circular inner circumferential surfaces are installed in the movable mold 2.
It is supported and interposed on the 4 side, and is configured to move forward and backward in the horizontal direction indicated by reference numeral D in the figure by a drive device (not shown). And mold 2 of the example
3 and 24 and cores 25 and 26 are for casting aluminum foil for vehicles, and the mold 2
A cavity 27, which is a space having the same shape as the aluminum foil, is formed between the protrusions 3 and 24 and the half-ring-shaped cores 25 and 26. On the other hand, below the machine base to which the fixed platen 21 is fixed,
An injection cylinder (not shown) is disposed so as to be vertically tiltable, and 28 is a plunger that is moved up and down by this injection cylinder, and 29 is a block that is moved up and down by another cylinder on the injection cylinder side.
At the upper end of this block 29 is a plunger 28.
An injection sleeve 30 fitted therewith is fixed concentrically, and as the block 29 rises, this injection sleeve is fitted into the sleeve hole 23a of the stationary mold 23 as shown. In addition, the injection sleeve 30
The block 29 is engaged in the notch 21a of the fixed platen 21, and when the block 29 is lowered, it is removed from the sleeve hole 23a of the injection sleeve 30, and the entire injection cylinder is tilted in the direction shown by the arrow E in the figure. The injection sleeve 30 is configured to stand up after injecting the molten metal 31 into the injection sleeve 30. The plunger 28 is provided with a plunger tip 28a as a head that is fitted into the inner hole of the injection sleeve 30. The plunger 28 is raised by the injection cylinder, and the plunger tip 28a pushes the molten metal 31 and injects it into the cavity 27. 32 is a cylinder 32a provided on the rod 28b of the plunger 28.
It is an auxiliary cylinder consisting of a piston rod 32b that moves forward and backward by pressure oil fed into the piston rod 32b.
It is configured to protrude from 8a for feeding.

Such a molten metal casting apparatus is provided with a device for reducing the diameter of the molten metal passage and shearing the solidified molten metal. That is, the fixed mold 23 has an upper plate 23 formed in a rectangular shape, stacked one on top of the other and joined with bolts.
b and a lower plate 23c, and as shown in FIG. sliding grooves 34, 35 on both sides formed in
are provided continuously, and these guide holes 3
3 and the sliding grooves 34 and 35 have a cylindrical shape with vertical openings closed by the upper plate 23b. and,
A gate plate 36 for solidified molten metal is movably fitted into the cylindrical guide hole 33 and the sliding grooves 34, 35. This gate plate 36 has a sleeve hole 37 into which the injection sleeve 30 is fitted, a molten metal hole 38 having the same diameter as the inner hole of the injection sleeve 30, and a constricted hole 39 which is considerably smaller than the inner hole of the injection sleeve 30. They are formed concentrically in this order from the 30 side, and the gate plate 36 has these holes 37,
Gate plate (right) 40 bordering the center of 38 and 39
and a gate plate (left) 41. These gate plates (right) 40 and gate plates (left)
41 refers to guide portions 40a and 41a that are slidably fitted into the guide hole 33, and the slide groove 3.
Sliding portions 40b, 4 which are slidably fitted to 4, 35.
1b and is formed in a T-shape, and the guide portion 40
The fitting tolerance between a and 40b is about 0.5 mm on one side, and the fitting tolerance between sliding parts 40b and 41b is about 0.1 mm or less on both sides. Each of the gate plates 40 and 41 configured in this way is connected to the piston rods 42a and 43a of the cylinders 42 and 43 respectively mounted on the lower plate 23c of the fixed mold 23.
It is fixed to and is configured to be moved by being driven by each cylinder 42, 43. In this embodiment, the stroke of the right cylinder 42 is approximately 15 mm to the left from the position shown in the figure, and the stroke of the left cylinder 43 is approximately 30 mm to the left from the position shown. When molten metal is injected into the cavity 27, pressure is applied to the head end side of the left cylinder 43, pushing the gate plates 40 and 41 to the right in the figure, and the shoulder 40c of the right gate plate 40 is pressed against the fixed plate. Lower plate 2 of mold 23
The gate plate 4 is pressed against the shoulder 23d of the gate plate 3c.
0 and 41 are restricted from moving to the right in the figure. Of course, this rightward movement regulation can also be done by the right cylinder 42, but if it is done by the shoulders 23d, 40c in this way, the position setting adjustment of the gate plates 40, 41 during injection is ensured. and easy to perform. With this configuration, the molten metal 3 filled into the cavity 27
1 is solidified, pressure is applied to the head end of the cylinder 42 or
Pressure is simultaneously applied to the head end side of the cylinder 43 and the rod end side of the cylinder 43, and the gate plate (right) 4
0 and the gate plate (left) 41 are both moved approximately 15 mm in the direction of separation from each other to ensure that the sheared biscuits are separated from the gate plates 40 and 41 and fall. Furthermore, on both front and rear sides of the fixed mold 23,
A pair of cylinders 44 and 45 as regulating members that regulate movement of the gate plates 40 and 41 in a direction perpendicular to the movement direction are connected to piston rods 44a and 4.
5a is fitted into a rod hole provided in the lower plate 23c of the fixed mold 23, and by applying pressure to the head end side, the piston rod 43
The tips of the gate plates a and 44a are configured to be pressed against the end faces of the center portions of the gate plates 40 and 41. When the gate plates 40, 41 are moved, the piston rods 44a, 45a are moved back and the gate plates 40, 41 are moved.
Move away from 0,41. Note that a runner 46 is bored in the upper plate 23b between the cavity 27 and the constricted hole 39.

The operation of the die casting machine configured as described above will be explained based on FIGS. 3a to 3f. In FIG. 3a, the injection sleeve 30 has been lowered together with the block 29, and the plunger 28 has been lowered within the injection sleeve 30. Further, the injection sleeve 30 is filled with a predetermined amount of molten metal 31 injected in an inclined state. Piston rod 42a of air cylinder 42 shown in FIG.
is moving backward, and the piston rod 43a of the air cylinder 43 is moving forward, and the shoulder 4 of the gate plate 40
0c is the shoulder portion 23d of the lower plate 23c of the fixed mold 23
The movement to the right in the figure is restricted by contacting with. Also, the piston rods 44a, 45a of both cylinders 44, 45 are moving forward, and the gate plate 42,
43. In this state, the block 29 is raised by a cylinder (not shown), and as shown in FIG.
After the injection sleeve 30 is inserted into the sleeve hole 23a of the fixed mold 23 and the sleeve hole 37 of the gate plates 40 and 41 as shown in FIG. Push up 31 and cavity 2
Inject into 7. At the end of injection, the auxiliary cylinder 3
The second piston rod 32b rises and protrudes from the plunger tip 28a to perform feeding. The shell generated within the injection sleeve 30 during injection is restricted from rising by the circumferential edges of the constricted holes 39 of the gate plates 40 and 41 and is compressed into a bellows shape, so that it does not enter the cavity 27. When filling the cavity 27 with the molten metal 31, the gate plates 40, 41 tend to thermally expand due to the high heat of the molten metal 31, and a large pressure of 1000 kg/cm ² is applied to the gate plates 40, 41 due to the injection of the molten metal 31. The gate plates 40, 41 try to bulge outwards due to the internal force of the cylinder 4.
Since the piston rods 44a and 45a of 4 and 45 are pressed together by cylinder pressure, the gate plates 40 and 41 swell due to the injection of molten metal, and the guide portion 4
0a, 41a, etc. are not pressed against the guide hole 33, etc., and are not seize up or their sliding movement is prevented. In addition, the constriction hole 39 does not open due to deformation of the shear plates 40, 41, and the movement of the gate plates 40, 41 becomes heavy during the subsequent shearing operation of the molten metal solidified material, and burrs and solid objects do not occur. No biting occurs. In this case, pressure is acting on the head end side of the piston rod 43a of the opening/closing cylinder 43 of the gate plate (left) 41, pushing the gate plate (left) 41 to the right, and the shoulder of the gate plate (right) 40 Since the portion (40c) is in contact with the shoulder portion 23d of the lower plate 23a and is restricted from moving in the right direction, the gate plates 40, 41 do not move in the opening/closing direction either.Of course, in this case , pressure may be applied to the head end side of the opening/closing cylinder 42 of the gate plate (right) 40 to restrict its movement to the right.

After the molten metal 31 in the cavity 27 is solidified and the injection sleeve 30 is lowered, the piston rods 44a, 45a of the front and rear air cylinders 44, 45 are moved back, and the gate plates 40, 41 are released from the pressure. Then, when the piston rod 42a of the right cylinder 42 is advanced, for example, by about 15 mm, and at the same time the piston rod 43a of the air cylinder 43 is retreated by the same amount, the solidified molten metal is squeezed into the runner hole 46, as shown in FIG. 3c. It is sheared from the boundary with the hole 39. In this case, the gate plates 40, 41
is not pressed by the piston rods 44a and 45a, so it moves smoothly.

Next, prior to mold opening, the piston rod 42a of the right cylinder 42 is moved back to its original position by about 15 mm, for example, as shown in FIG. For example, further than the position shown in c.
When they are moved back about 15 mm in the same direction, the gate plates 40 and 41 on both sides separate from the sheared compound so-called biscuit 47 attached thereto, and the biscuit 47 falls. At this time, as shown by the chain line in FIG.
A biscuit support rod 47a having a convex portion that fits into a hole formed when the tip of b is activated during the feeder.
from below the biscuit 47 and remove the biscuit 4.
If the gate plates 40 and 41 are opened while supporting the biscuits 7 and preventing left and right movement, the biscuits 47 will not escape even when the force of pushing the biscuits 47 and the gate plates 40 and 41 is strong, and the biscuits will be able to move downward. It can be dropped reliably. FIG. 3e shows the biscuit 47 falling, and after the biscuit 47 has fallen, the piston rod 43a of the cylinder 43 is advanced, for example, by about 30 mm, as shown, to return it to its original position at the time of injection.

Then, as shown in FIG. 3f, the movable platen 22
When the mold is opened by raising the mold, the product in the cavity 27 is held on the movable mold 24 side and rises, so the cores 2 on both sides rise together with the movable mold 24.
After opening 5 and 26 outward and separating them from the product, when a protrusion pin of a protrusion device (not shown) is lowered, the product 48 falls. Therefore, the product 48 is received by an arm of a product unloading device (not shown) and transported outside the machine.
discharge. One casting cycle is completed by clamping the mold after taking out the product. The removed product 48 comes with a runner 49, so either cut it off with a cutting tool on a lathe, or provide a thin section at the base of the runner 49 and punch it with a punch or the like from the direction indicated by the arrow in Fig. 3f. Alternatively, the runner 49 may be folded.

The above example shows an example in which the present invention is applied to a normal vertical mold clamping and vertical casting die casting machine, but in reality, the injection device, product ejecting device, mold spraying device, etc. are installed in separate stations. It is desirable to apply this method to a rotary die-casting machine. That is, both the molds 23 and 24 are held openable and closable at positions that divide the rotary table into three equal parts in the circumferential direction, and an injection station, a product ejection station, and a mold spray station are arranged on the orbit of the rotary table. , injection of molten metal at the injection station to the mold that stops intermittently at each station, shearing of the biscuit 47 at the product take-out station, opening of the mold, and extrusion and take-out of the product;
The molds are sprayed at the mold spray station.

FIG. 4 is a longitudinal cross-sectional view of the main parts of a die-casting machine showing another embodiment of the present invention corresponding to FIG. 1, and members having the same structure as those shown in FIGS. , and the explanation thereof will be omitted. In this example, as is clear from a comparison with FIG.
The convex portion 24a of the movable mold 24 is raised, and the fixed mold 2
The convex portion 23d of No. 3 is lowered. By doing this, the aluminum foil as a cast product is cast upside down, and the decorative side on which the design is applied becomes the runner 46 side, but the large diameter biscuit 14 as shown in Fig. 6 is not attached to this decorative side. Since only a thin runner is included, there is a degree of freedom in design.

Although the example in which the gate plates 40 and 41 are used for shearing the solidified material has been described above, the gate plates 40 and 41 can also be used for opening and closing the melt passage. FIG. 5 is a vertical cross-sectional view of the main parts of another embodiment of this kind corresponding to FIG. Reference numerals are given and explanations thereof are omitted. In this example,
The gate plate (right) 40A and the gate plate (left) 41A are the piston rods 42 of the cylinders 42A and 43A.
These left and right gate plates 40A and 41A are configured to move forward and backward in opposite directions as the piston rods 42a and 43a move forward and backward. Cylinder 42A, 43
The stroke of A is larger than that of the previous embodiment, and at the forward limit of the gate plates 40A and 41A, the molten metal passage has a small diameter indicated by the symbol _D1 in the figure, and the gate plate 40
At the retraction limit of A, 41A, the molten metal passage is set to be the same as the inner diameter of the injection sleeve 30, as shown by reference numeral _D2 in the figure.

With this configuration, the gate plates 40A and 41A are moved forward as shown in the figure to make the molten metal passage smaller, and the front and rear cylinders 44 and 45 are actuated in the same way as in the previous embodiment to move the piston rod 44a. , 45a and gate plate 40A,
Press the side of 41A. After doing this, the plunger 28 is moved forward and the molten metal is poured into the cavity 27.
When injected, the shell formed along the inner peripheral surface of the injection sleeve 30 and the end surface of the plunger tip 28a is pushed by the plunger tip 28a and tries to head toward the cavity 27, but there are gate plates 40A and 41A. Therefore, the shell is compressed into a bellows-like shape between the end surfaces of the peripheral edges of the gate plates 40A and 41A, and does not enter the cavity 27. After the molten metal injected into the cavity 27 is solidified and cooled, the front and rear piston rods 44
Retract a and 45a and remove the gate plates 40A and 41A.
The movement of the piston rods 42a and 43 is lifted.
a is moved backward to open the gate plates 40A and 41A until they have the same diameter as the inner diameter of the injection sleeve 30. When the mold is opened, the product in the cavity 27 is held on the movable mold 24 side and rises, but since the gate plates 40A and 41A are open, the gate plate 4
The biscuits formed below 0A and 41A also rise along with the product. Thereafter, the biscuit can be removed from the product taken out from the cavity 27 in the same manner as in the previous embodiment by breaking the thin solidified material solidified within the holes of the gate plates 40A, 41A with a hammer or the like.

In addition, in each of the above embodiments, the gate plates 40, 41,
Although an example has been shown in which the regulating member for regulating the movement of 40A and 41A in the front and back direction is formed as air cylinders 44 and 45 so as to be movable in both the front and rear directions, one side is fixed at the movement regulating position, and the one side's movement regulating member is fixed at the movement regulating position. Only a cylinder or the like may be formed to be movable. In addition, although each of the above embodiments has been described as an example in which the present invention is applied to a die casting machine for casting aluminum foil,
The product is not limited to aluminum foil and may be any product. Further, the present invention can be applied not only to die casting machines but also to injection molding machines for plastics.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, in a vertical mold clamping and vertical injection type injection molding apparatus,
In the melt passage between the injection sleeve and the mold cavity, there is a hole with a smaller cross-sectional area than the inner hole of the injection sleeve, and a gate plate that is divided and formed with the center of this hole as a border is moved in the horizontal direction. By making the molten material passage smaller than before, excess solidified material such as biscuits attached to the product can be reduced by shearing the solidified material that has solidified in this reduced channel with the gate plate. It is economical because the amount of molten metal consumed is reduced, and the runner part of the product is small, so even if this part becomes a decorative surface, the aesthetics will not be impaired, and the mold can be used to add designs. This allows for greater freedom in design. Furthermore, by reducing the size of the molten material passage, the molten solidified material solidified within the injection sleeve during injection is blocked by the reduced passage and does not enter the cavity, resulting in a significant improvement in the quality of the product. If the molten solidified material is not sheared by the gate plate, the solidified material in the injection sleeve can be injected along with the product by opening the gate plate when the mold is opened. moreover,
Regulating members that restrict movement in a direction perpendicular to the direction of movement of the gate plate are provided on both sides of the gate plate, and at least one of them is movable, so that the gate plate can be moved easily during injection of melt. By regulating the thermal expansion of the gate plate and the phenomenon that the gate plate tends to bulge outward due to internal pressure due to injection, the gate plate deforms and the required amount for sliding is controlled. There will be no gaps, and no burrs or solid matter will get stuck in the gaps due to deformation. Therefore, by opening the regulating member when moving the gate plate, the gate plate can be moved smoothly.

[Brief explanation of drawings]

1 to 5 show an embodiment of the injection molding apparatus according to the present invention, FIG. 1 is a vertical cross-sectional view of the main parts of a vertical mold clamping and vertical injection type die casting machine to which this is applied, and FIG. Figure 1 is a cc sectional view, Figures 3 a to f are longitudinal sectional views of main parts shown to explain the operation, and Figure 4
5 and 5 are longitudinal sectional views of the main parts of other embodiments of the present invention corresponding to FIG. 1, and FIG. 6 is a longitudinal sectional view of the main parts of a conventional vertical mold clamping and vertical injection die casting machine. It is a diagram. 23...Fixed mold, 23b...Top plate, 23c...
... Lower plate, 24 ... Movable mold, 27 ... Cavity, 28 ... Plunger, 30 ... Injection sleeve, 31 ... Molten metal, 33 ... Guide hole, 34, 35
...Sliding groove, 36...Gate plate, 39...Neck hole, 40, 40A...Gate plate (right), 40a,
41a...guiding part, 40b, 41b...sliding part,
41, 41A...Gate plate (left), 42, 43,
42A, 43A...Air cylinder, 42a, 43
a... Piston rod, 44, 45... Air cylinder, 44a, 45a... Piston rod.

Claims (1)

[Claims] 1. In an injection molding device that injects the melt in a vertical injection sleeve into the cavity of a vertically clamped mold from directly below the mold, in the melt passage between the injection sleeve and the cavity, A gate plate having a hole having a smaller cross-sectional area than the inner hole of the injection sleeve is divided and formed with the center of the hole as a boundary, and is provided so as to be movable in the horizontal direction,
An injection molding apparatus characterized in that regulating members for regulating the movement of the gate plate in a direction orthogonal to the direction of movement of the gate plate are provided on both sides of the gate plate, and at least one of the regulating members is formed to be movable.