JP2009166048A - Floor plate for powder supply box of powder molding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable reduction of leakage of powder out of a powder supply box caused when molding a green compact by a powder molding device without causing the complication of the powder molding device and the increase of equipment cost and without using a sealing material made of an organic substance such as a packing or a felt which affects the quality of a product. <P>SOLUTION: A protrusion 12 with a size to be put in the contour of the upper surface of a die 1 which surrounds the outlet of a casting hole 11 is arranged at the lower surface of a floor sheet 10 which casts powder P supplied to the inside of the powder supply box 6 into a cavity C opened at the upper surface of the die 1 through a casting hole 11 by sliding on a shoe plate 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a floor plate used as a component of a bottom wall in a powder feeding box of a powder molding apparatus, and more specifically, reduces powder leakage when powder is poured from a powder feeding box into a cavity opened on the upper surface of a die. It relates to an effective floorboard.

  The powder forming device is used for forming green compacts for sintered parts, and is used between a die and a lower punch or between a die, a lower punch and a core using a powder supply device. The raw material powder is supplied to the cavity formed in the step, and then the raw material powder in the cavity is pressed with a punch to obtain a green compact.

  The powder feeding device used at this time includes a powder feeding box that slides on the shoe plate and moves from the retracted position to the powder feeding position to the cavity, and a hose that feeds the powder in the hopper to the powder feeding box. The powder feeding box is a box of a size that allows the die to be taken inside the side wall, and the powder fed into the powder feeding box via the hose is introduced into the cavity, and the powder is filled into the cavity.

  For example, the following Patent Documents 1 and 2 are cited as documents describing the powder feeding apparatus. In Patent Document 1, a suction port is provided at the bottom portion of the powder feeding box (shoe box) and in the vicinity thereof, and the suction port is sucked with a suction device, thereby suppressing the leakage of powder from the powder feeding box and leaking. Disclosed is a technique that enables powder recovery.

Patent Document 2 discloses a common powder feeding box in which at least one core is detachably attached to a powder container in the powder feeding box, and the size of the outlet of the powder feeding box is changed by the core. Is used to suppress the variation in the quality of the green compact that occurs when molding green compacts having different shapes and sizes. Further, this Patent Document 2 also discloses that a packing is attached to the lower surface of the core to prevent the powder from leaking from the powder feeding box.
JP-A-5-5102 JP-A-1-208403

  In order to form green compacts having different shapes and sizes using a common powder feeding box, it has been conventionally practiced to provide a flooring plate corresponding to the core of Patent Document 2 in the powder feeding box. The floor plate constitutes the bottom wall of the powder feeding box, and has a hole for pouring powder. By changing and using the floorboards with different sizes and shapes of the insertion holes, the shape and size of the green compact to be molded can be accommodated.

  However, when the slat is used, the powder leaks out of the powder feeding box through a gap formed between the top surface of the die and the slab. As shown in FIG. 5, the powder feeding box 6 slides on the shoe plate 2 and moves between the retraction point and the powder charging point, but when the floor plate 10 moves on the die 1, An inevitable step is formed between the upper surface 1a of the die 1 surrounded by a shoe plate.

  When the floor plate 10 slides on the shoe plate 2 in this state, a gap g is created between the upper surface 1a of the die 1 and the lower surface of the floor plate 10 as shown in FIG. The gap g is not so large. However, if there is this gap g, a powder retention space is created, and powder P accumulates on the die 1 and leaks to the outside due to the movement of the powder feeding box 6. The amount of powder leakage per molding due to the gap g is limited, but in the production of mass-produced products, the amount of leakage in each molding is accumulated, so it cannot be ignored for the entire lot. The amount of raw material is wasted.

  In order to eliminate the waste, it was studied to reduce powder leakage from the gap. However, if the powder feeding box provided with the suction port disclosed in the above-mentioned Patent Document 1 is used, it is possible to meet the demand for reduction of leakage. Increase in equipment costs is inevitable.

  Moreover, the powder supply box which patent document 1 discloses has attached to the lower surface the felt which partitions between the inner side of a box and a suction port, and the abrasion of the felt occurs. Therefore, it takes time to replace the felt, and in addition, it is conceivable that felt wear powder is mixed into the powder and deteriorates the quality of the sintered product, which is the final product (causes the density of the component to decrease). .

  The method disclosed in Patent Document 2 also closes the gap with the packing that causes wear and chipping, so it is necessary to frequently replace the packing, which adversely affects the operating rate of the powder molding apparatus. Further, it is conceivable that the wear powder or fragments of the packing are mixed into the powder, thereby deteriorating the quality of the sintered product as the final product.

  This invention reduces the powder leakage from the powder feeding box caused by the step between the shoe plate and the die upper surface that occurs when the green compact is molded by the powder molding machine, making the powder molding machine more complex and increasing the equipment cost. It is an object of the present invention to enable reduction without using organic sealing materials such as packing and felt, which have an adverse effect on product quality.

  In order to solve the above-mentioned problems, in the present invention, a powder molding apparatus in which a die and a shoe plate are installed on a die plate is used to constitute a bottom wall of a powder feeding box of the apparatus, The following devices were added to the floor plate for sliding the powder supplied into the powder feeding box into the cavity opened on the upper surface of the die from the charging hole provided therein. That is, the bottom surface of the floor plate is provided with a convex portion that surrounds the outlet of the charging hole and is large enough to be taken into the outline of the upper surface of the die.

  The convex portion is preferably provided at a position close to the outlet along the edge of the outlet of the charging hole.

  The height of the convex portion is preferably set to be larger than the step between the upper surface of the shoe plate and the upper surface of the die.

  Since the bottom plate of the present invention has a convex portion surrounding the outlet of the charging hole on the lower surface, when the convex portion moves on the die, the gap between the die and the bottom plate is blocked by the convex portion. The powder is charged into the cavity. Thereby, the outflow of the powder from the powder supply box is suppressed, and the amount of leakage is reduced as compared with the conventional case.

  When the convex portion changes from the die to the shoe plate or from the shoe plate to the die, a gap due to a step between the die and the shoe plate is instantaneously formed between the die and the floor plate. Therefore, it is difficult to completely eliminate the leakage of powder, but it is possible to reduce about 50 to 80% of the leakage amount in the current powder feeding using the floor plate without the convex portion by installing the convex portion. is there.

  The reduction of the leakage amount can be realized only by providing a convex portion on the lower surface of the floor plate, so that the powder molding apparatus is not complicated and the equipment cost is not increased. Further, since no sealing material such as packing or felt is used, the quality of the product is not deteriorated.

Note that the base plate provided with the convex portion at a position close to the outlet along the edge of the outlet of the charging hole does not have a gap between the base plate and the die on the inner side of the convex portion, and between the base plate and the die. The powder does not enter the In addition, since the size of the convex portion is reduced by bringing the convex portion close to the edge of the outlet of the insertion hole, the gap formed between the die and the base plate is small when the convex portion is transferred from the shoe plate to the die and from the die to the shoe plate. Thus, the amount of powder leakage is further reduced.

  In addition, the base plate in which the height of the convex portion is set larger than the step between the upper surface of the shoe plate and the upper surface of the die is such that the convex portion is placed on the upper surface of the die when in the powder feeding position. Completely close the gap. Therefore, this also has a high effect of reducing the leakage amount.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a flooring box for a powder feeding box according to the present invention will be described below with reference to FIGS. In the figure, 1 is a die of a powder molding apparatus, 2 is a shoe plate, 3 is a lower punch, 4 is a core, 5 is a die plate supporting the die 1 and the shoe plate 2, 6 is a powder feeding box, and 7 is a hopper (not shown). Hose for transporting the powder in the powder feed box 6, 8 is a slide guide for the powder feed box 6, 9 is a power transmission link of the drive mechanism that transmits the drive force to the powder feed box 6 (the drive mechanism is the only link) Reference numeral 10 denotes a floor plate removably attached to the lower portion of the powder supply box 6.

  The floor plate 10 has an insertion hole 11 through which the powder P supplied from the hopper to the inside of the powder supply box 6 via the hose 7 is introduced into the cavity C opened on the upper surface of the die 1. Further, the lower surface has a convex portion 12 surrounding the outlet of the charging hole 11.

  The convex portion 12 is sized to be taken into the contour 13 {see FIG. 1 (b)} on the upper surface of the die 1. Here, the convex portion 12 is formed in a ring shape, and is provided at a position in contact with the edge of the outlet along the edge of the outlet of the charging hole 11. Further, the height 12 of the convex portion 12 (see FIG. 1A) is set larger than the step d (see FIG. 4) between the upper surface 2a of the shoe plate 2 and the upper surface 1a of the die 1. .

  There is a step d shown in FIG. 4 between the upper surface 1 a of the die 1 and the upper surface 2 a of the shoe plate 2. Although the level difference d is a small dimension that is less than 1 mm, the die 1 is lowered from the upper surface 2a of the shoe plate 2 as shown in FIG. The height h of the convex portion 12 is set higher than the step d. Therefore, when the convex portion 12 is placed on the shoe plate 2, the lower surface of the portion excluding the convex portion of the floor plate 10 is the shoe plate 2. The same amount as the height h of the convex portion in FIG.

  The floor plate 10 thus configured is attached to the lower portion of the powder supply box 6 to constitute a powder supply device of the powder molding apparatus. The powder feeding box 6 of the powder feeding device is driven by the drive mechanism and repeatedly moves between the solid line position (retract point) in FIG. 1 (a) and the solid line position (powder point) in FIG. 3 (a). .

  The action at that time will be described in more detail. When the powder feeding box 6 moves forward from the position in FIG. 1A to the left in the drawing, the convex portion 12 on the bottom surface of the floor plate moves onto the die 1 as shown in FIG. At the beginning of the transfer, most of the convex portion 12 is on the shoe plate 2 so that the powder feeding box 6 is maintained in a horizontal state. For this reason, the convex portion 12 is lifted from the upper surface 1a of the die 1 and A gap is formed between the upper surface 1a and the convex portion 12, but at this stage, the powder supply box 6 moves to the side having the gap, so that it is difficult for the powder to leak out.

  When the powder feeding box 6 further advances and the center of gravity of the powder feeding box 6 moves onto the die, the powder feeding box 6 is tilted. For this reason, the convex portion 12 is partially left on the shoe plate 2 with the remaining one remaining. The part climbs onto the die 1 to narrow the gap, and the further advance of the powder feeding box 6 thereafter moves the entire convex part 12 onto the die 1 as shown in FIG. There is no gap between them. Therefore, the amount of powder leakage when the powder feeding box moves forward hardly occurs.

  Next, the powder supply box 6 finishes charging the powder P into the cavity C at the position shown in FIG. 3A, and then returns to the right in the drawing. At this time, the convex portion 12 rides on the shoe plate 2 from the die 1. Therefore, the right end side of the convex portion 12 in the figure does not float from the upper surface of the die 1 or the upper surface of the shoe plate 2, and the leakage of powder from that portion to the rear portion of the powder feeding box becomes almost zero.

  The leakage of the powder when using the floor plate 10 is caused by the fact that the left side of the convex portion 12 in the drawing rises from the die 1 in the process of returning the powder feeding box 6 from the position of FIG. Is considered to occur when it moves to the right in the figure (until the convex portion 12 is completely transferred onto the shoe plate 2). Since the period is instantaneous, the absolute amount of leakage is much less than in the prior art.

Examples of the present invention will be given below.
A floorboard (invention) with the following specifications was prototyped.
・ Material: S45C
-Diameter of input hole (= inner diameter of convex part 12): 140 mm
・ Outer diameter of convex part 12: 150 mm
-Height of convex part 12: 5 mm
・ Thing board thickness: 20mm

Next, a powder forming apparatus in which a prototype invented floorboard is attached to a powdering box, and a powdering apparatus in which a floorboard without a convex portion (conventional product) is attached to the powdering box are powder-molded using a 200 ton press. Adopted in the apparatus, the degree of powder leakage was evaluated.
The evaluation test was performed by molding the following green compacts 1-5.
・ Green compact 1: Rotor for variable valve timing mechanism of automobile, Material: Iron-based alloy, Basic unit weight 304g
・ Green compact 2: cylinder head for engine, material: iron-based alloy, basic unit weight 175g
・ Green compact 3: Disc-shaped part for pump, Material: Iron-based alloy, Basic weight 152g
・ Green compact 4: Housing vane for automobile, Material: Iron alloy, Basic weight 259g
・ Green compact 5: Cylindrical insert parts, Material: Iron alloy, Basic unit weight 211g

The green compact 1 had a molding number of 1000 per lot and a molding speed of 10.0 spm (10 moldings per minute).
The green compact 2 has a molding number of 1000 pieces and a molding speed of 11.0 spm. The green compact 3 has a molding number of 1000 pieces of one lot, a molding speed of 12.0 spm, and the green compact 4 has one lot. The number of moldings was 1000, the molding speed was 7.3 spm, and the green compact 5 was 3500 moldings per lot and the molding speed was 7.2 spm.

  Molding was performed under the above conditions, and the amount of powder leakage per lot when using the base plate of the invention and using the base plate of the conventional product was investigated. Table 1 summarizes the results and the leakage rate reduction rate when using the inventive product, which is obtained by the formula {1- (leakage amount when using the inventive product / leakage amount when using the conventional product) × 100}.

This test result clearly shows the effectiveness of providing a convex portion of a size that can be taken into the contour of the upper surface of the die on the bottom surface of the floor plate.

(A) sectional view and (b) plan view showing a powder feeding device adopting the floorboard of this invention (A) sectional view and (b) plan view showing a state in which the powder feeding box of the powder unmolding device in FIG. 1 has advanced halfway toward the powder feeding point (A) sectional view and (b) plan view showing a state in which the powder feeding box of the powder unmolding device in FIG. 1 has advanced to the powder feeding point Sectional view showing details of step between die and shoe plate The figure which shows the clearance gap which arises between the upper surface of die | dye, and a lower surface of a base plate when using the powder non-molding apparatus which employ | adopted the base plate of a conventional product

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Die 2 Shoe plate 3 Lower punch 4 Core 5 Die plate 6 Powder supply box 7 Hose 8 Slide guide 9 Power transmission link 10 Base plate 11 Injection hole 12 Convex part 13 Contour of die upper surface C Cavity P Powder h Convex part height d Level difference between the top surface of the die and the shoe plate

Claims (2)

A shoe plate that is employed in a powder forming apparatus in which a die (1) and a shoe plate (2) are installed on a die plate (5) and constitutes a bottom wall of a powder feeding box (6) of the apparatus, the shoe plate (2) An insertion hole (11) through which the powder (P) supplied by sliding to the inside of the powder supply box (6) is introduced into a cavity (C) opened on the upper surface of the die (1). Prepared,
Supply of a powder molding apparatus characterized in that a lower surface is provided with a convex portion (12) that surrounds the outlet of the charging hole (11) and is taken into the contour (13) of the upper surface of the die (1). Floor box for powder box.   The height (h) of the convex portion (12) is set larger than the step (d) between the upper surface (2a) of the shoe plate (2) and the upper surface (1a) of the die (1). A base plate for a powder feeding box of the powder molding apparatus according to 1.

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