Molding apparatus

Abstract

To solve the problem of the conventional molding apparatus in which when molding a product having a female screw hole, a structure of the apparatus is enlarged.SOLUTION: An apparatus for molding a product F having a female screw hole H comprises: a mold 2 having a cavity 1; a screw-shaped pin 3 for molding the female screw hole H; a shaft body 4 with the screw-shaped pin 3 fixed to a tip portion; a holder 5 for holding the shaft body 4 so as to be rotatable around an axis and advanceable / retractable in the axial direction; a pinion 6 connected to a base end portion of the shaft body 4; and a rack 8 that engages with the pinion 6 to be advanced / retracted by a hydraulic cylinder 7. The screw-shaped pin 3 is protrudable toward / sinkable from the cavity 1. The screw-shaped pin 3 is retracted in the axial direction while being rotated at a high torque, to allow the screw-shaped pin 3 to be pulled out of the product F, which realizes simplification or size reduction of a structure of the apparatus.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a molding apparatus used for molding a product having a female screw hole in casting or resin molding.

Background Art

[0002] Conventionally, as a molding apparatus as described above, for example, there is one described in Patent Document 1. Patent Document 1 describes a casting apparatus including an upper mold having an inclined pin in a hanging state and a slide core having an inclined hole into which the inclined pin is inserted, and the slide core is moved horizontally by the sliding contact between the inclined pin and the inclined hole as the upper mold rises.

[0003] By the way, when molding a product having a female screw hole by casting or resin molding, a screw-shaped pin corresponding to the female screw hole is used. However, when the product is demolded, the thread of the screw-shaped pin is in an undercut state, so it cannot be pulled out linearly. Therefore, conventionally, the product has been demolded by rotating the screw-shaped pin with a servo motor and retracting it in the axial direction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the above-described conventional molding apparatus, during molding, the molten metal or resin contacts the entire surface of the screw-shaped pin and solidifies in that state to form a product. Therefore, in order to retract the screw-shaped pin that is in strong contact with the product while rotating it, a high-torque servo motor or a speed reducer is required, and there is a problem that the apparatus structure becomes large.

[0006] The present invention has been made in view of the above-described conventional situation, and is a molding apparatus for molding a product having a female screw hole, and an object thereof is to provide a molding apparatus capable of simplifying and miniaturizing the apparatus structure.

Means for Solving the Problems

[0007] The molding apparatus according to the present invention is an apparatus for molding a product having a female screw hole, and includes a mold having a cavity which is a molding space, a screw pin for molding the female screw hole, a shaft body having the screw pin fixed to its tip portion, a holder for holding the shaft body rotatable about its axis and movable forward and backward in the axial direction, a pinion coaxially connected to the base end portion of the shaft body, and a rack engaged with the pinion and driven forward and backward by a hydraulic cylinder. And the above-described molding apparatus is characterized in that the screw pin can project into and retract from the cavity.

Effects of the Invention

[0008] Since the molding apparatus according to the present invention adopts the above-described configuration, when the product is demolded, the hydraulic cylinder, the rack, and the pinion cause the screw pin to be retracted in the axial direction while rotating the screw pin at a high torque together with the shaft body, and the screw pin is pulled out from the product, so that simplification and miniaturization of the apparatus structure can be realized.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0010] <First Embodiment> The molding apparatus shown in FIGS. 1 and 2 is an apparatus for molding a product having a female screw hole, and is applicable to both casting using molten metal and resin molding using molten resin including injection molding.

[0011] The molding apparatus includes a mold 2 having a cavity 1 which is a molding space. The mold 2 forms the cavity 1 with a fixed mold 2A on the right side in the figure and a movable mold 2B which can move forward and backward with respect to the fixed mold 2A. Although not shown, it is provided with an ejector mechanism for pushing out the product and demolding it.

[0012] The molding apparatus of this embodiment includes a screw-shaped pin 3 for forming a female screw hole on the fixed mold 2A, a shaft body 4 having the screw-shaped pin 3 fixed to its tip, and a holder 5 for rotatably holding the shaft body 4 around its axis and advancing and retreating it in the axial direction. And the molding apparatus includes a pinion 6 coaxially connected to the base end of the shaft body 4, and a rack 8 engaged with the pinion 6 and driven to advance and retreat by a hydraulic cylinder 7, and has a structure in which the screw-shaped pin 3 can project into and out of the cavity 1.

[0013] The screw-shaped pin 3 has a male screw shape corresponding to the female screw hole. In the figure, the thread is shown by a vertical line, but the actual thread is inclined. The shaft body 4 has the screw-shaped pin 3 coaxially fixed to the tip (small diameter end) of a tapered portion 4A whose diameter gradually decreases toward the cavity 1, and has a large diameter portion 4B having a constant diameter at the base end (large diameter end) of the tapered portion 4A.

[0014] An empty space 2C opened to the outside of the mold (right side in FIG. 1) is formed in the fixed mold 2A. The tapered portion 4A of the shaft body 4 is arranged in this empty space 2C, and the tip portion of the tapered portion 4A including the screw-shaped pin 3 penetrates through the partition wall portion 2D between the cavity 1 and the empty space 2C in the axial direction in a movable manner.

[0015] In the fixed mold 2A, the holder 5 is disposed outside the mold of the void 2C, has a through hole 5A penetrating the shaft body 4, and has a female screw portion 5B on the inner surface of the through hole 5A. On the other hand, the shaft body 4 has a male screw portion 4C on the large-diameter portion 4B that is screwed into the female screw portion 5B of the holder 5.

[0016] And the screw pin 3 and the male screw portion 4C of the shaft body 4 have screw pitches that can rotate synchronously with each other as will be described later. Therefore, the female screw portion 5B of the holder 5 also corresponds to the male screw portion 4C of the shaft body 4C. The pinion 6 is fixed to the end of the large-diameter portion 4B of the shaft body 4. The hydraulic cylinder 7 connects a cylinder rod 7A to the end of the rack 8, and drives the cylinder rod 7A to expand and contract to move the rack 8 forward and backward.

[0017] Here, since the molding device can project and retract the screw pin 3 with respect to the cavity 1, the screwing range of the male screw portion 4C of the shaft body 4 and the female screw portion 5B of the holder 5 corresponds to the movable range in the axial direction of the screw pin 3, and is set to the length dimension in the axial direction of the screw pin 3 or a length dimension greater than that. Further, the rack 8 has a width dimension that is sufficiently larger than the width dimension of the pinion 6 so that the pinion 6 can move within the range of the length in the axial direction of the screw pin 3 or a length greater than that.

[0018] As shown in FIG. 3, the molding device having the above configuration advances the movable mold 2B with respect to the fixed mold 2A to close the cavity 1. At this time, the molding device holds the screw pin 3 in a protruding state in the cavity 1. Therefore, the shaft body 4 and the pinion 6 are disposed at the forward position.

[0019] Next, as shown in FIG. 4, the molding device fills the cavity 1 with a molten material M that is molten metal or molten resin, and holds it for a predetermined time to solidify the molten material M to form a product. At this time, since the entire surface of the screw pin 3 is in contact with the molten material M and solidifies in that state, the entire surface is firmly adhered to the product.

[0020] Therefore, as shown in FIG. 5, the molding device advances the rack 8 with the hydraulic cylinder 7. As a result, the molding device rotates the shaft body 4 and the screw pin 3 integrally about the axis together with the pinion 6 by the high-torque force exerted by the hydraulic cylinder 7.

[0021] At this time, since the holder 5 and the shaft body 4 are screwed together by the female screw portion 5B and the male screw portion 4C, the screw pin 3, the shaft body 4, and the pinion 6 retreat in the axial direction. Finally, the screw pin 3 is inserted into the fixed mold 2A with respect to the cavity 1, and the screw pin 3 is completely pulled out from the product F. Thereafter, as shown in FIG. 6, the molding device withdraws the movable mold 2B and operates an ejector mechanism (not shown) to take out the product F having the female screw hole H.

[0022] FIG. 7 is a flowchart for explaining the above molding process. That is, when the molding starts (starts) in step S1, the filling of the molten material is started in step S2, and the filling of the molten material is completed in step S3. Next, in the molding process, after the molten material solidifies, the retreat of the shaft body 4 is started in step S4, and the retreat of the shaft body 4 is completed in step S5. As a result, the screw pin 3 is completely pulled out from the product F.

[0023] Thereafter, the molding device opens the mold in step S6, pushes out the product in step S7, takes out the product in step S8, then starts the forward movement of the shaft body 4 in step S9, and ends the forward movement of the shaft body 4 in step S10 to project the screw pin 3 into the cavity 1. In this state, the mold is closed in step S11 to shift to the next molding.

[0024] Further, the molding device has a screw pitch in which the screw pin 3 and the male screw portion 4C of the shaft body 4 can rotate synchronously with each other. As is clear from Table 1 below, it is possible to rotate them synchronously without setting both to the same pitch.

[0025]

Table 1

[0026] The above-mentioned molding device is a device for molding a product F having a female screw hole H. When the product F is demolded, the screw-shaped pin 3 is rotated at a high torque together with the shaft body 4 and retracted in the axial direction, so that the screw-shaped pin 3 can be easily and surely pulled out from the product F, and the simplification and miniaturization of the device structure can be realized.

[0027] Further, in the above-mentioned molding device, since the shaft body 4 and the holder 5 are configured to be screwed together by a male screw portion 4C and a female screw portion 5B, the rotation operation of the rack 8 and the pinion 6 is utilized to ensure the advance and retreat operation functions of the screw-shaped pin 3 and the shaft body 4, and it can contribute to further simplification and miniaturization of the structure.

[0028] Furthermore, in the above-mentioned molding device, since the screw-shaped pin 3 and the male screw portion 4C of the shaft body 4 have screw pitches that can rotate synchronously with each other, when the screw-shaped pin 4 is pulled out while rotating from the product F, the load applied to the screw-shaped pin 3 can be suppressed, and a situation where the thread is damaged can be prevented in advance.

[0029] The molding device according to the present invention is not limited to the above-described embodiment only, and can be appropriately changed without departing from the gist of the present invention. Further, in the above embodiment, the molding of a product having one female screw hole was exemplified, but it is also applicable to the manufacture of a product having a plurality of female screw holes.

[0030] When manufacturing a product having a plurality of female screw holes, the molding device may be configured to include, for example, a plurality of sets of combinations of a screw-shaped pin, a shaft body, a holder, a pinion, a hydraulic cylinder, and a rack, a configuration including a plurality of sets of combinations of a screw-shaped pin, a shaft body, and a pinion, and adopting a common holder, and further, a configuration adopting a common hydraulic cylinder and a rack.

Explanation of Signs

[0031] 1 Cavity 2 Mold 2A Movable mold 2B Fixed mold 3 Threaded Pin 4 Shaft 4C Female Threaded Portion 5 Holder 5A Through-Hole 5B External Threaded Portion 6 Pinion 7 Hydraulic Cylinder 8 Rack F Product H Female Threaded Hole

Claims

1. An apparatus for molding a product having a female screw hole, comprising: a mold having a cavity as a molding space; a screw pin for molding the female screw hole; a shaft body having the screw pin fixed to its tip; a holder for rotatably holding the shaft body about its axis and advancing and retracting it in the axial direction; a pinion coaxially connected to the base end of the shaft body; a rack engaged with the pinion and driven to advance and retract by a hydraulic cylinder; The molding apparatus, characterized in that the screw pin can project into and retract from the cavity.

2. The holder has a through hole penetrating the shaft body, the through hole has a female screw portion on its inner surface, The molding apparatus according to claim 1, characterized in that the shaft body has a male screw portion screwed into the female screw portion.

3. The molding apparatus according to claim 2, characterized in that the screw pin and the male screw portion of the shaft body have a screw pitch that allows synchronous rotation with each other.

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