The present invention relates to a nut working (or molding) machine and, more particularly, to a molding die structure for forming oblique teeth on a rivet nut.
A rivet nut is available for a metal sheet plate. The rivet nut is combined with an anchor hole of the metal sheet plate after the rivet nut is pressed and riveted. Thus, the rivet nut is screwed onto a bolt for use with an operator. A conventional rivet nut 10 in accordance with the prior art shown in
The primary objective of the present invention is to provide a molding die structure for directly forming oblique teeth on a rivet nut by a nut molding machine during a successive molding and forming process of the rivet nut, to enhance the efficiency of production.
In accordance with the present invention, there is provided a molding die structure for forming oblique teeth on a rivet nut comprising a mold seat, a first forging die, a second forging die, and a retaining member. The mold seat is provided with a mold cavity. The mold cavity is provided with a threaded portion. The first forging die is inserted into the mold cavity of the mold seat.
The first forging die is provided with a die cavity and a nut cavity. The nut cavity is connected to the die cavity. The first forging die has an oblique shoulder formed between the nut cavity and the die cavity. The second forging die is inserted into the die cavity of the first forging die. The second forging die has a hollow cylindrical shape. The second forging die has a front end provided with an oblique resting face. The second forging die has an inner face provided with an oblique toothed portion and a guide hole. The oblique toothed portion is connected to the guide hole. The oblique toothed portion includes a plurality of oblique teeth. The retaining member is screwed into the threaded portion of the mold seat and limits the first forging die and the second forging die in the mold cavity of the mold seat. The second forging die and the die cavity of the first forging die form a low friction contact.
Preferably, the oblique resting face of the second forging die has a slope corresponding to that of the oblique shoulder of the first forging die.
Preferably, the second forging die has an outer wall in non-contact with an inner wall of the die cavity of the first forging die.
Preferably, the second forging die has a height less than a depth of the die cavity of the first forging die. The height of the second forging die is more than 99.5% of the depth of the die cavity of the first forging die.
Preferably, each of the oblique teeth has an inclined angle ranged between 35° and 45°.
According to the primary advantage of the present invention, the molding die structure cooperates with the nut working machine to work the rivet nut so that the flange of the rivet nut is directly formed with the oblique teeth during the working process.
According to another advantage of the present invention, the flange of the rivet nut is directly formed with the oblique teeth without needing a secondary working process, thereby simplifying the working procedure, shortening the working time, and greatly increasing yield of the rivet nut.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.
Referring to the drawings and initially to
The mold seat 20 is provided with a mold cavity 21. The mold cavity 21 of the mold seat 20 is used to receive the first forging die 30 and the second forging die 40. The mold cavity 21 is provided with a threaded portion 22.
The first forging die 30 is inserted into the mold cavity 21 of the mold seat 20. The first forging die 30 is provided with a die cavity 31 and a nut cavity 32. The die cavity 31 receives the second forging die 40. The nut cavity 32 is connected to the die cavity 31. The first forging die 30 has an oblique shoulder 33 formed between the nut cavity 32 and the die cavity 31.
The second forging die 40 is inserted into and loosely fitted in the die cavity 31 of the first forging die 30. The second forging die 40 has a hollow cylindrical shape. The second forging die 40 has a front end provided with an oblique resting face 41. The second forging die 40 has an inner face provided with an oblique toothed portion (or grain portion or pattern portion) 42 and a guide hole 43. The oblique toothed portion 42 is connected to the guide hole 43. The oblique toothed portion 42 includes a plurality of oblique teeth 421.
The retaining member 23 is screwed into the threaded portion 22 of the mold seat 20 and limits the first forging die 30 and the second forging die 40 in the mold cavity 21 of the mold seat 20. Thus, the second forging die 40 and the die cavity 31 of the first forging die 30 form a low friction contact.
In the preferred embodiment of the present invention, the oblique resting face 41 of the second forging die 40 has a slope corresponding to that of the oblique shoulder 33 of the first forging die 30.
In the preferred embodiment of the present invention, the second forging die 40 has an outer wall in non-contact with an inner wall of the die cavity 31 of the first forging die 30.
In the preferred embodiment of the present invention, the outer wall of the second forging die 40 is tapered from the oblique resting face 41 to the rear end of the second forging die 40 through 5°.
In the preferred embodiment of the present invention, the second forging die 40 has a height less than a depth of the die cavity 31 of the first forging die 30. Preferably, the height of the second forging die 40 is more than 99.5% of the depth of the die cavity 31 of the first forging die 30. Thus, the second forging die 40 and the die cavity 31 of the first forging die 30 form a low friction connection.
In the preferred embodiment of the present invention, each of the oblique teeth 421 has an inclined angle ranged between 35° and 45°.
In the preferred embodiment of the present invention, the second forging die 40 has a shape corresponding to that of the die cavity 31 of the first forging die 30, with a tolerance defined therebetween.
In the preferred embodiment of the present invention, the threaded portion 22 of the mold seat 20 is close to an open end of the mold cavity 21.
In the preferred embodiment of the present invention, the retaining member 23 is provided with an external thread screwed into the threaded portion 22 of the mold seat 20.
In operation, referring to
When the rivet nut 50 is pushed out of the nut cavity 32 of the first forging die 30 by the rear punch head 60b, the rivet nut 50 is not rotated during operation. At this time, the second forging die 40 and the die cavity 31 of the first forging die 30 form a low friction contact. Thus, the second forging die 40 easily performs a rotation with the slope of the oblique teeth 421 of the oblique toothed portion 42 as shown in
Accordingly, the molding die structure cooperates with the nut working machine to work the rivet nut 50 so that the flange 51 of the rivet nut 50 is directly formed with the oblique teeth 52 during the working process. In addition, the flange 51 of the rivet nut 50 is directly formed with the oblique teeth 52 without needing a secondary working process, thereby simplifying the working procedure, shortening the working time, and greatly increasing yield of the rivet nut 50.
Although the invention has been explained in relation to its preferred embodiment(s) as mentioned above, it is to be understood that many other possible modifications and variations can be made without departing from the scope of the present invention. It is, therefore, contemplated that the appended claim or claims will cover such modifications and variations that fall within the scope of the invention.
Number | Date | Country | Kind |
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109125697 | Jul 2020 | TW | national |