JP4313711B2 - Die-cast frame manufacturing method - Google Patents

Description

  The present invention relates to a method of manufacturing a die-cast frame used as a frame for a liquid crystal television or the like, and more specifically, a boss of a die-cast frame having a substantially flat plate shape and having boss portions formed with female threads from both directions on both front and back sides. The present invention relates to a method for manufacturing a die-cast frame in which tapping on a part is completed only by work from one side.

Conventionally, a die-cast frame having a substantially flat plate shape is used as a frame of a liquid crystal television or the like. The die-cast frame is manufactured by a die-cast machine, and then sent to a machining process by a transfer machine. A tapping is applied to a pre-formed boss portion, and a screw for mounting a component is screwed. Was forming. Since the bosses for forming this female screw are usually formed on both the front and back surfaces of a substantially flat die-cast frame, in the transfer machine, after tapping the boss part on one side, the die-cast frame After tapping, the boss part of the remaining surface was tapped. In addition, in the case of a thin die-cast frame having a substantially flat plate shape, the boss portion where the female screw on each of the front and back surfaces is formed at substantially the same level as the tapping process, so the female screw penetrates the boss portion. If there is no problem, the tapping on the back side can be performed in the same process as the tapping on the front side. However, when the die-cast frame is used for an electronic device such as a liquid crystal television, if the female screw of the boss part is penetrated during tapping, chips that are good electrical conductors are generated when the screw is screwed. Passing through the hole at the bottom of the splatter and splashing into the electronic device, it causes a failure of the electronic device. Therefore, in the die-cast frame for an electronic device, it is absolutely necessary to form a closed bag shape at the bottom of the female screw of the boss portion. There are Patent Document 1 and Patent Document 2 as conventional techniques in which the internal thread of the boss portion is not penetrated. These are states in which the bottom of the electronic device is closed without passing through the female screw to which the component mounting screw is screwed.
JP-A-4-249083, FIG. Japanese Patent Laid-Open No. 10-11954, FIG.

  As described above, when a die-cast frame for electronic equipment is tapped on the bosses on both the front and back surfaces in the machining process by the transfer machine to form the internal thread, The cast frame was inverted and the remaining surface was tapped again, and both sides had to be closed in a bag shape without penetrating the bottom of the female screw. The inversion process of the die cast frame in this transfer machine is also a loss of work time. If possible, it is desired to omit the inversion process and shorten the machining time by the transfer machine. Therefore, the present invention shortens the machining process by the transfer machine by adopting a structure in which chips are not scattered even if the female threads on both the front and back sides are formed only by tapping from one side without inverting the die-cast frame. An object of the present invention is to propose a method of manufacturing a die-cast frame that makes it possible to do this.

  In order to solve the above-mentioned problems, the present invention is a method of manufacturing a die-cast frame having boss portions in which female threads are formed from both directions on both the front and back surfaces, and penetrates the boss portions corresponding to the back side in advance. A tapped hole is formed in advance, and a tapped hole is formed in the same direction as the boss portion corresponding to the surface side in the same step as the tapped portion of the boss portion corresponding to the front surface side, thereby forming a female screw that penetrates. After that, an opening corresponding to the bottom of the boss corresponding to the back side is closed. That is, in the die-cast frame having a substantially flat plate shape and having boss portions in which both sides of the front and back surfaces are formed with female threads from the respective directions, a tapped pilot hole penetrating in advance to the boss portion on the back surface side is formed, and the back surface In the same process as the tapping of the front-side boss part with a ring-shaped projection formed in advance around the lower hole on the bottom surface of the side boss part, the boss part on the back side After forming a female screw that penetrates by tapping from the bottom side, a mortar-shaped punch is lowered from above the ring-shaped protrusion to deform the protrusion inward to open the bottom of the female screw. Block the part. The cross-sectional shape of the ring-shaped protrusion is preferably a vertical side on the inside and a hypotenuse on the outside. In addition, in a die-cast frame having a substantially flat plate shape and a boss portion where female threads are formed from both directions on both front and back surfaces, a tapped hole that penetrates the boss portion on the back side in advance is formed, In the same process as the tapping of the front side boss with the front side up, after tapping the bottom side of the boss on the back side to form an internal thread, a ring is formed from above the bottom of the internal thread. The bottom of the female screw is deformed inward by lowering the shaped punch to close the bottom opening of the female screw. Furthermore, in a die-cast frame having a substantially flat plate shape and a boss portion where female threads are formed from both directions on both the front and back surfaces, a pilot hole for tapping that penetrates the boss portion on the back side in advance is formed, In the same process as the tapping of the front side boss part with the front side being the upper side, after tapping the bottom side of the boss part on the back side to form a female screw that penetrates, the bottom part of the female screw on the back side is formed. A screw with a short thread is screwed to close the bottom opening of the female thread. Furthermore, in a die-cast frame having a substantially flat plate shape and having a boss portion in which both sides of the front and back surfaces are formed with a female screw from each direction, a tapped pilot hole penetrating the boss portion on the back side is formed in advance. In the same process as the tapping of the front side boss part with the front side up, the back side boss part is tapped from the bottom side to form a female thread that penetrates, and then the bottom part of the rear side female thread The bottom opening of the female screw is closed by inserting a short rivet and then caulking its head. In addition, in a die-cast frame having a substantially flat plate shape and a boss portion where female threads are formed from both directions on both front and back surfaces, a tapped hole that penetrates the boss portion on the back side in advance is formed, In the same process as the tapping of the boss part on the front side with the front side being the upper side, after tapping the boss part on the back side from the bottom side to form a female screw that penetrates, the bottom opening of the female screw on the back side A plate piece larger than the opening is bonded to the portion to close the bottom opening of the female screw.

  As described above, according to the present invention, in the same process as the tap processing of the boss portion corresponding to the front surface side of the die cast frame, the tap processing is performed from the same direction as the tap processing of the boss portion corresponding to the front surface side to penetrate. After forming the female screw, the opening corresponding to the bottom of the boss corresponding to the back side is closed, so that the boss on the front side and the boss on the back side can be tapped in the same process. Since the die-cast frame reversal process is no longer necessary, the processing time is shortened and the cost can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 4 are cross-sectional views showing the processing steps of the first embodiment of the present invention. FIG. 1 shows a state in which the die-cast frame 1 is set in a transfer machine with the front side facing up. This state shows a step of tapping a boss portion (not shown) for forming a female screw used for screwing a component from the surface side. In this state, the boss portion on the surface side (not shown) is transferred by a transfer machine. However, non-penetrating tapping is performed leaving the bottom. The boss portion 2 on the back surface side shown in FIG. 1 protrudes to the back surface side (downward) of the die-cast frame 1, and when tapped and formed with an internal thread, components are attached from the back surface side using screws. Is.

  In the present invention, the boss portion 2 on the back surface side is tapped in the same process as the tapping of the front surface boss portion (not shown) from the front surface side. That is, for the boss portion 2 on the back surface side, a tapped hole 3 is formed through the boss portion 2. At the same time, a ring-shaped projection 4 is formed in advance around the lower hole 3 of the bottom surface portion of the boss portion 2. The tip direction of the protrusion 4 is slightly inward. Next, as shown in FIG. 2, the tapping blade 5 is lowered from above the bottom surface side of the boss portion 2, and tapping is performed inside the lower hole 3. At this time, the blade 5 is sufficiently lowered to form a female screw over the entire length of the lower hole 3. This tapping is performed without reversing the die-cast frame 1 in the same process as tapping on the surface-side boss portion (not shown).

  Next, as shown in FIG. 3, the mortar-shaped punch 6 whose section inside is lowered from above the boss part 2 which has been tapped, and the protrusion 4 is plastically deformed from the outside to the inside. As shown, the bottom (upper end in the figure) of the lower hole 3 is closed. As a result, the bottom surface of the boss portion 2 on the back surface side is blocked, and even if chips are generated when screws are screwed onto the boss portion 2, they are not scattered outside. In addition, the punching process by the punch 6 is performed in the next process of the tapping process for the boss portion 2 and the like. During the transition from the tap process to the punch process, the die cast frame 1 is performed without being inverted.

  FIG. 5 is a cross-sectional view showing the second embodiment. In this embodiment, the protrusion 4 is not provided on the bottom surface portion of the boss portion 2 in the first embodiment. The bottom surface portion of the boss portion 2 is formed flat, and the punch 7 is a ring having a wedge-shaped cross section. Keep it in shape. As in the first embodiment, after the tapping of the pilot hole 3 is performed, the punch 7 is lowered and the punch 7 is bitten into the bottom surface portion of the boss portion 2 in a V shape, so that the inside of the biting portion is Is moved toward the center of the lower hole 3 so that the bottom (upper end in the figure) of the lower hole 3 is closed.

  FIG. 6 is a cross-sectional view showing the third embodiment. In this embodiment, the protrusion 4 is not provided on the bottom surface portion of the boss portion 2 in the first embodiment, and the bottom surface portion of the boss portion 2 is formed flat. Similarly to the first embodiment, after the tapping of the lower hole 3 is executed, the screw 8 having a short threaded portion is screwed and fixed to the bottom portion (upper end in the drawing) of the formed female screw portion. The bottom part (the upper end in the figure) is closed. Compared with the first and second embodiments, the third embodiment reduces the processing time of the transfer machine because there is no punching process.

  FIG. 7 is a cross-sectional view showing the fourth embodiment. In this embodiment, the protrusion 4 is not provided on the bottom surface portion of the boss portion 2 in the first embodiment, and the bottom surface portion of the boss portion 2 is formed flat. As in the first embodiment, after tapping the pilot hole 3, a short rivet 9 is inserted into the bottom (upper end in the figure) of the formed female screw, and the head is caulked to rivet The bottom 9 (the upper end in the figure) of the lower hole 3 is closed by fixing it so that it does not go through 9.

  FIG. 8 is a cross-sectional view showing the fifth embodiment. In this embodiment, the recess 4 is formed by lowering the bottom surface portion of the boss portion 2 by one step without providing the protrusion 4 on the bottom surface portion of the boss portion 2 in the first embodiment. Similar to the first embodiment, after the tapping of the lower hole 3 is performed, the bottom portion (upper end in the figure) of the lower hole 3 is adhered to the formed depression 11 by bonding the plate piece 12 with an adhesive. It was designed to be closed. In the fourth embodiment, as compared with the first and second embodiments, the machining time of the transfer machine is shortened because there is no punching process. The plate piece 12 can be attached by double-sided tape, welding, or the like in addition to attachment by an adhesive. It is also possible to attach the plate piece 12 without forming the recess 11.

  The present invention is not limited to a die-cast frame used as a frame for a liquid crystal television or the like, and is generally a flat plate shape and is a die-cast frame having a boss portion in which both sides are formed with female screws from both directions. It can be used for die-cast frames used in general industrial equipment.

It is sectional drawing which shows the manufacturing process of the 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the 1st Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the 2nd Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the 3rd Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the 4th Embodiment of this invention. It is sectional drawing which shows the manufacturing process of the 5th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Die-casting frame 2 Boss part 3 Pilot hole 4 Protrusion 5 Cutting tool 6,7 Punch 8 Screw 9 Rivet 11 Recess 12 Plate piece

Claims (8)

A method of manufacturing a die-cast frame having a boss part in which a female screw is formed from each direction on both the front and back surfaces,
From the same direction as the tap processing of the boss portion corresponding to the front surface side in the same step as the tap processing of the boss portion corresponding to the front surface side, by previously forming a tap hole penetrating the boss portion corresponding to the back surface side. A method of manufacturing a die-casting frame, comprising: forming an internal thread penetrating through tapping and then closing an opening corresponding to a bottom portion of a boss portion corresponding to the back surface side. In a die-cast frame having a boss portion that is substantially flat and has internal threads formed on both front and back sides from each direction,
A pilot hole is formed in advance for tapping through the boss corresponding to the back side, and a ring-shaped protrusion is formed around the pilot hole at a position corresponding to the bottom surface of the boss corresponding to the back side. In addition, after tapping from the same direction as the tapping of the boss portion corresponding to the surface side in the same process as the tapping of the boss portion corresponding to the front surface side to form the internal thread that penetrates, the inside of the cross section is a mortar shape A method of manufacturing a die-casting frame, wherein the ring-shaped protrusion is deformed inward using a punch and the opening corresponding to the bottom of the boss corresponding to the back side is closed. In the manufacturing method of the die-casting frame according to claim 2,
A method of manufacturing a die-cast frame, characterized in that the cross-sectional shape of the ring-shaped protrusion is a vertical side on the inside and a hypotenuse on the outside. In a die-cast frame having a boss portion that is substantially flat and has internal threads formed on both front and back sides from each direction,
A pilot hole is formed in advance for tapping through the boss corresponding to the back side, and a ring-shaped protrusion is formed around the pilot hole at a position corresponding to the bottom surface of the boss corresponding to the back side. In addition, after tapping from the same direction as tapping of the boss corresponding to the surface side in the same process as tapping of the boss corresponding to the surface side, forming a female thread that penetrates, a ring-shaped punch A method of manufacturing a die-cast frame, wherein a portion corresponding to the bottom portion of the boss portion corresponding to the back surface side is deformed inward to close the opening. In a die-cast frame having a boss portion that is substantially flat and has internal threads formed on both front and back sides from each direction,
A pilot hole is formed in advance for tapping through the boss corresponding to the back side, and a ring-shaped protrusion is formed around the pilot hole at a position corresponding to the bottom surface of the boss corresponding to the back side. In addition, after tapping from the same direction as the tapping of the boss portion corresponding to the front surface side in the same process as the tapping of the boss portion corresponding to the front surface side, the internal thread penetrating is formed and then corresponding to the back surface side. A die cast frame manufacturing method, wherein a screw having a short threaded portion is screwed into an opening corresponding to a bottom portion of a boss portion to be closed to close the opening. In a die-cast frame having a boss portion that is substantially flat and has internal threads formed on both front and back sides from each direction,
A pilot hole is formed in advance for tapping through the boss corresponding to the back side, and a ring-shaped protrusion is formed around the pilot hole at a position corresponding to the bottom surface of the boss corresponding to the back side. In addition, after tapping from the same direction as the tapping of the boss portion corresponding to the front surface side in the same process as the tapping of the boss portion corresponding to the front surface side, the internal thread penetrating is formed and then corresponding to the back surface side. A die cast frame manufacturing method, wherein a rivet having a short length is inserted into an opening corresponding to a bottom portion of a boss portion to be closed, and then the rivet head is caulked to close the opening. In a die-cast frame having a boss portion that is substantially flat and has internal threads formed on both front and back sides from each direction,
A pilot hole is formed in advance for tapping through the boss corresponding to the back side, and a ring-shaped protrusion is formed around the pilot hole at a position corresponding to the bottom surface of the boss corresponding to the back side. In addition, after tapping from the same direction as the tapping of the boss portion corresponding to the front surface side in the same process as the tapping of the boss portion corresponding to the front surface side, the internal thread penetrating is formed and then corresponding to the back surface side. A die cast frame manufacturing method, wherein a plate piece larger than the diameter of the opening is bonded to an opening corresponding to the bottom of the boss portion to close the opening. 8. The method of manufacturing a die-cast frame according to claim 1, wherein the boss portion is formed in a bag shape.

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