Extrusion die device

An extrusion die device includes a first die having a shaping hole. An inner periphery of the shaping hole has a plurality of twisted guiding portions. A second die includes a plurality of guiding holes. A bridge is formed between two adjacent guiding holes. A plurality of tongues extends from a surface of each bridge and each includes an input end face contiguous to the bridge and an output end face whose projection on the surface of the bridge has an angular shift relative to the input end face. A side of the second die is coupled to an input side of the first die. The tongues are received in the shaping hole. Material is squeezed through a passage between each tongue and the inner periphery of the shaping hole and rotates according to the twisting direction of the tongues, forming a hollow object with an integrally formed helical rib.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an extrusion die device and, more particularly, to an extrusion die device for forming a hollow object with an integrally formed helical rib by one-time extrusion.

2. Description of the Related Art

Extrusion includes applying pressure to force a heated metal material to pass through a shaping hole of a die, obtaining a produce having a hollow object or a solid rod. Metal tubes in rehabilitation devices or sport devices have specific requirements in strength. In an example shown inFIG. 1, the metal tube1includes a central rib11to enhance the bending strength. The metal tube1has uniform cross sections, and the central rib11provides enhanced strength of the metal tube1in the extending direction of the central rib11. However, the structural strength of the other portions of the metal tube1not supported by the central rib11may be insufficient. The wall thickness of the metal tube1or the central rib11can be increased to enhance the structural strength of these portions, but the costs and the weight of the metal tube1are both increased.

Formation of helical rods or helical tubes by extrusion is known. Furthermore, helical fins can be formed on an outer periphery of a hollow object by extrusion. However, formation of a hollow object with an integrally formed central helical rib by one-time extrusion utilizing conventional die devices without changing the wall thickness of the hollow object or the central helical rib for providing the hollow object with uniform structural strength in the radial direction is still difficult.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide an extrusion die device for forming a hollow object having an integrally formed helical rib to possess uniform strength in the radial direction.

Another objective of the present invention is to provide an extrusion die device for forming a hollow object having an integrally formed helical rib by one-time extrusion.

A further objective of the present invention is to provide an extrusion die device for forming a hollow object with less material and reduced costs.

An extrusion die device according to the preferred teachings of the present invention includes a first die having input and output sides. The first die further includes a shaping hole extending from the input side through the output side. A second die includes a central axis and first and second sides spaced along the central axis. The second die further includes a plurality of guiding holes each extending from the first side to the second side. A plurality of bridges each is formed between two of the guiding holes adjacent to each other and extends from an inner periphery of the second die to the central axis for the bridges to meet each other. A plurality of tongues each includes an input end face contiguous to one of the bridges and an output end face. A projection of the output end face of each tongue on the surface of one of the bridges where the input end face disposed has a first angular shift relative to the input end face of the tongue. The second side of the second die is coupled to the input side of the first die. The tongues are received in the shaping hole. A passage is formed between each tongue and an inner periphery of the shaping hole.

In use, material is squeezed through the passage between each tongue and the inner periphery of the shaping hole and rotates according to the twisting direction of the tongues, forming a hollow object with an integrally formed helical rib possessing uniform structural strength in the radial direction.

Preferably, the shaping hole is a conical hole tapering from the input side toward the output side of the first die.

Preferably, the shaping hole includes a central axis, with the input and output sides of the first die spaced along the central axis of the shaping hole, with the inner periphery of the shaping hole having a plurality of guiding portions, with two of the guiding portions adjacent to each other having an adjoining portion extending along an axis not intersecting the central axis of the shaping hole.

Preferably, each guiding portion includes an input end edge on the input side of the first die and an output end edge on the output side of the first die. A projection of the input end edge of each guiding portion on the output side has a second angular shift relative to the output end edge of the guiding portion.

Preferably, a position where the bridges meet includes a recessed portion between two of the tongues adjacent to each other.

Preferably, the central axis of the first die is coaxial with the central axis of the second die.

Preferably, each of the bridges includes first and second surfaces spaced along the central axis of the second die, and the second die further includes a splitting section having a first end contiguous to the first surface of the bridges in a position where the bridges meet and a second end adapted for splitting flow of metal material into the plurality of guiding holes.

Preferably, the splitting section has decreasing cross sectional areas from the first end toward the second end of the splitting section.

Preferably, directions of the first angular shift and the second angular shift are the same.

Preferably, a shape of the output end face of each tongue is a shape of each channel of a hollow object to be formed by the extrusion die device. Preferably, a container including a compartment is further comprised, wherein the compartment has two open ends, with one of the two open ends aligned and in communication with the guiding holes of the second die.

Where used in the various figures of the drawings, the same numerals designate the same or similar parts. Furthermore, when the terms “first”, “second”, “inner”, “end”, “portion”, “section”, “radial”, and similar terms are used herein, it should be understood that these terms have reference only to the structure shown in the drawings as it would appear to a person viewing the drawings and are utilized only to facilitate describing the invention.

DETAILED DESCRIPTION OF THE INVENTION

An extrusion die device according to the preferred teachings of the present invention is shown in the drawings. According to the preferred form shown, the extrusion die device includes a first die3and a second die4. The first die3includes input and output sides31and32. A shaping hole33extends from the input side31through the output side32of the first die3and includes an input end34in the input side31and an output end35in the output side32. The input and output sides31and32of the first die3are spaced along a central axis of the shaping hole33. In the most preferred form shown, the input end34is larger than the output end35. Specifically, the shaping hole33is a conical hole tapering from the input side31toward the output side32of the first die3. The shape of the output end35is circular so that the resultant hollow object formed by the extrusion die device is cylindrical. The shaping hole33further includes an inner periphery having a plurality of guiding portions36between the input end34and the output end35. Two of the guiding portions36adjacent to each other have an adjoining portion38extending along an axis not intersecting the central axis of the shaping hole33. Each guiding portion36includes an input end edge362on the input side31of the first die3and an output end edge364on the output side32of the first die3. A projection of the input end edge362of each guiding portion36on the output side32has an angular shift relative to the output end edge364of the guiding portion36. Namely, the guiding portions36are twisted in a direction about the central axis of the shaping hole33.

In the preferred form shown, the second die4includes a central axis A coaxial with the central axis of the shaping hole33. The second die4includes first and second sides41and42spaced along the central axis A. The second die4further includes a plurality of guiding holes43each extending from the first side41to the second side42. A bridge44is formed between two of the guiding holes43adjacent to each other. Each bridge44extends from an inner periphery of the second die4to the central axis A and includes first and second surfaces442and444spaced along the central axis A, while the bridges44meet at the central axis A. A plurality of tongues45formed on the second surface444of each bridge44and extends away from the bridge44, with the tongues45preferably being spaced out and close to the central axis A. Preferably, numbers of the guiding holes43, bridges44, and tongues45are the same. According to the most preferred form shown inFIG. 2, the second die4includes two guiding holes43, two bridges44, and two tongues45. However, the number of the guiding holes43does not have to be related to the number of the tongues43. Each tongue45includes an input end face46contiguous to the bridge44and an output end face47. The bridge44includes two bulged portions48connecting with and corresponding to the input end faces46of the tongues45, forming a recessed portion49between the bulged portion48. The shape of the output end face47of each tongue45is the shape of each channel of the hollow object to be formed by the extrusion die device.

In the most preferred form shown, the tongues45encircle the central axis A of the second die4with identical distances to the said central axis A; that is, when the number of the tongues45is two, these two tongues45are symmetrically located on opposite sides of the central axis A. A projection of the output end face47of each tongue45on the second surface444of the bridge44has an angular shift relative to the input end face46of the tongue45. The direction of the angular shift between the input and output end faces46and47of each tongue45can be the same or opposite to that of the angular shift between the input and output end edges362and364of the guiding portions36.

In the most preferred form shown, the second die4further includes a substantially wedge-shaped splitting section40having a first end401contiguous to the first surface442of the bridge44and a second end402. The splitting section40is disposed at the place where the bridges meet each other and has decreasing cross sectional areas from the first end401toward the second end402of the splitting section40.

Referring toFIGS. 2 and 3, in assembly, the second side42of the second die4is coupled to the input side31of the first die3. The tongues45are received in the shaping hole33of the first die3. A passage is formed between each tongue45and the inner periphery of the shaping hole33. The output end face47of each tongue45is preferably flush with the output end35of the shaping hole33. However, the output end face47of each tongue45does not have to be flush with the output end35of the shaping hole33. Furthermore, the output end face47of each tongue45is spaced from a periphery of the output end35of the shaping hole33. A container5containing metal material for forming the hollow object is coupled to the first side41of the second die4. The container5includes a compartment51having two open ends. One of the open ends of the compartment51is aligned and in communication with the guiding holes43of the second die4. The splitting section40of the second die4is located in the compartment51of the container5. However, the splitting section40can be arranged outside of the compartment51of the container5if desired.

Referring toFIGS. 3 through 5, in forming a hollow object with a helical rib by the extrusion die device according to the preferred teachings of the present invention, the metal material is heated to be in a molten state and fed into the compartment51of the container5. A rod is utilized to apply pressure to the molten metal material. Thus, the molten metal material is squeezed and moves toward the splitting section40of the second die4. The flow of the molten metal material is guided by the splitting section40into the guiding holes43and branches into two streams of molten metal material after passing through the splitting section40and the bridge44. Due to provision of the recessed portion49of the bridge44, the two streams of molten metal material are guided to the tongues45and rotate through an angle. Furthermore, the two streams of molten metal material merge under high temperature and high pressure. An interior portion of the merged flow of molten metal material twists along each tongue45, and an exterior portion of the merged flow of molten metal flow twists along each guiding portion36. Thus, the molten metal material is twisted while passing through and being guided by the guiding portions36of the first die3and the tongues45of the second die4. Namely, during forming of the hollow object by extruding the molten metal material, the molten metal material is twisted and, thus, forms the hollow object2with an integrally formed helical rib21(FIG. 6) by one-time extrusion.

As shown inFIG. 6, the hollow object2formed by the extrusion die device according to the preferred teachings of the present invention includes the helical rib21dividing the hollow object2into two channels22. Each channel22is substantially helical and extends from one end through the other end of the hollow object2along the helical rib21. Thus, the hollow object2with the integrally formed helical rib21formed by one-time extrusion possesses uniform structural strength in the radial direction without changing the wall thickness of the hollow object2or the helical rib21, saving the material costs.

Referring toFIG. 7, an extrusion die device according to the preferred teachings of a specific embodiment of the present invention for illustration of alteration in guiding holes43and bridges44is shown. Specifically, a second die numbered as “6” is provided. The second die6includes a central axis A′ coaxial with the central axis of the shaping hole33, first and second sides61and62spaced along the central axis A′, four guiding holes63each extending from the first side61to the second side62, and four bridges64each formed between two of the guiding holes63adjacent to each other. Each bridge64extends from an inner periphery of the second die6to the central axis A′ and has two opposite surfaces spaced along the central axis A′ and respectively disposed at the first and second sides61and62, while the four bridges64meet at the central axis A′. Four tongues65respectively extend from the surface of the four bridges64, which is disposed on the second side62, and away from the bridge64. Preferably, the tongues65are spaced out and close to the central axis A′.

Please refer toFIGS. 7 through 9now. Each tongue65includes an input end face66contiguous to the bridge64and an output end face67. Preferably, the four input end faces66encircle the central axis A′ with an identical peripheral distance between any two input end faces66that are peripherally adjacent. The shape of the output end face67of each tongue65is the shape of each channel of the hollow object to be formed by the extrusion die device. A projection of the output end face67of each tongue65on the surface of the bridge64, where the tongue65extends from, has an angular shift relative to the input end face66of the tongue65, which can be observed throughFIGS. 8 and 9. The direction of the angular shift between the input and output end faces66and67of each tongue65can be the same or opposite to that of the angular shift between the input and output end edges362and364of the guiding portions36.

Referring toFIGS. 7 and 10, in assembly, the second side62of the second die6is coupled to the input side31of the first die3, with the tongues65received in the shaping hole33of the first die3. A passage is formed between each tongue65and the inner periphery of the shaping hole33. Thereby, in forming a hollow object with a helical rib by the extrusion die device according to the preferred teachings of the present invention, the metal material is heated to be in a molten state. When a flow of the molten metal material is guided into the guiding holes63and branches into four streams of molten metal material after passing by the bridge64, the four streams of molten metal material are guided to rotate through an angle by the tongues65. Furthermore, the four streams of molten metal material merge under high temperature and high pressure. An interior portion of the merged flow of molten metal material twists along each tongue65, and an exterior portion of the merged flow of molten metal flow twists along each guiding portion36. Thus, the molten metal material is twisted while passing through and being guided by the guiding portions36of the first die3and the tongues65of the second die6. Namely, during forming of the hollow object by extruding the molten metal material, the molten metal material is twisted and, thus, forms a hollow object7with four integrally formed helical ribs71(FIG. 11) by one-time extrusion.

As shown inFIG. 11, the hollow object7formed by the extrusion die device according to the preferred teachings of the specific embodiment of the present invention includes the helical ribs71dividing the hollow object7into four channels72. Each channel72is substantially helical and extends from one end through the other end of the hollow object7along the helical ribs71. Thus, the hollow object7with the integrally formed helical ribs71formed by one-time extrusion possess uniform structural strength in the radial direction without changing the wall thickness of the hollow object7or the helical ribs71, saving the material costs.