TWI909451B - Workpiece mold - Google Patents

Abstract

A workpiece mold is used to replace the conventional wax mold for casting a metal. The workpiece mold is a mold of a club head shell, and includes a crown, with an opening profile and a buffering portion, integrally connected to the opening profile. The buffering portion has at least one buffering hole. The workpiece mold is formed of a composition via 3D printing. The composition includes 15-25wt% of acrylate monomer, 15-25wt% of ethoxylated bisphenol A diacrylate and 0.5-5wt% of photoinitiator. This can reduce costs and shorten the overall time for metal casting molding.

Description

Workpiece mold

This invention relates to a workpiece mold, and more particularly to a workpiece mold that is an alternative to a wax mold.

When forming a workpiece through investment casting, a wax model corresponding to the shape of the workpiece is usually pre-formed. This wax model is then repeatedly dipped in slurry and sand, and after sintering and solidification, it is melted and removed from the workpiece shell mold to obtain the workpiece shell mold. Finally, molten metal is poured into the workpiece shell mold and solidified to obtain the metal casting. However, before forming the wax model, a wax mold of the corresponding shape must be pre-made, which is time-consuming and costly. Furthermore, when the shape requirements of the metal casting change, the old wax mold must be scrapped and cannot be reused, resulting in waste.

In view of this, the conventional wax molds used to form the shells of workpieces do indeed need to be improved.

To solve the above problems, the purpose of this invention is to provide a workpiece mold that can replace the traditional wax mold used for casting metal, thereby reducing costs and shortening the overall time for metal casting.

The directional terms or similar terms used throughout this invention, such as "front," "back," "left," "right," "top," "bottom," "inside," "outside," and "side," are primarily for reference to the directions in the accompanying diagrams. These directional terms or similar terms are only used to assist in explaining and understanding the various embodiments of this invention and are not intended to limit this invention.

The use of the quantifiers “a” or “one” for the elements and components described throughout this invention is for convenience and to provide the general meaning within the scope of this invention; in this invention, it should be interpreted as including one or at least one, and the concept of a single element also includes plural cases, unless it expressly means otherwise.

The terms “combination,” “assembly,” or similar terms used throughout this invention mainly include those that allow the components to be separated without damaging them after connection, or those that make the components inseparable after connection. These are terms that those with ordinary knowledge in the art can choose based on the material of the components to be connected or the assembly requirements.

The present invention discloses a workpiece mold, which is a rod head shell mold, and includes a crown having an opening profile and a cushioning portion integrally connected to the opening profile. The cushioning portion has at least one cushioning hole. The workpiece mold is formed by 3D printing of an assembly comprising 15-25% acrylate monomer, 15-25% bisphenol A diacrylate ethoxylate, and 0.5-5% photoinitiator by weight.

Accordingly, the workpiece mold of the present invention is formed by 3D printing of the composition, thus having a one-piece molding structure. This allows thermal expansion stress to occur at the buffer area rather than at the opening contour, maintaining the integrity of the opening contour. In addition, the workpiece mold can not only maintain a coefficient of thermal expansion and thermal deformation temperature similar to workpiece molds made of wax, but also has better strength. It can replace the traditional wax molds used for casting metal, thereby reducing costs and shortening the overall time of metal casting.

The acrylate monomer is ethylene glycol diacrylate. Thus, this acrylate monomer system can possess photoreactivity and a better curing rate.

The photoinitiator is diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide. Thus, the photoinitiator can initiate the polymerization reaction of the acrylate monomer and the oligomer, thereby producing a curing effect.

The workpiece mold includes a bottom with an open profile and a buffer portion integrally formed and connected to the open profile. The buffer portion has at least one buffer hole. This ensures that thermal expansion stress occurs at the buffer hole and not at the open profile, thus maintaining the integrity of the open profile of the crown.

The tensile strength of the workpiece mold is greater than 20 MPa. This gives the workpiece mold better strength, reduces expansion cracks caused by temperature changes, and improves the quality of the shell mold.

The tensile modulus of the workpiece mold is greater than 1500 MPa. This gives the workpiece mold better strength, reduces expansion cracks caused by temperature changes, and improves the quality of the shell mold.

The workpiece mold has a coefficient of thermal expansion of 121~130ppm/℃ and a heat deformation temperature of 46~53℃. Thus, the workpiece mold can maintain a coefficient of thermal expansion and heat deformation temperature similar to those of workpiece molds made of wax.

To make the above and other objects, features and advantages of the present invention more apparent, preferred embodiments of the present invention are given below and described in detail with reference to the accompanying drawings; in addition, those marked with the same symbols in different drawings are considered the same and their descriptions will be omitted.

The composition of the present invention for forming workpiece molds comprises 15-25% acrylate monomer, 15-25% bisphenol A diacrylate ethoxylate and 0.5-5% photoinitiator by weight percentage.

The acrylate monomer can be a reactive monomer with photoreactivity and a good curing rate, so that the composition used to mold the workpiece can be cured by irradiation with ultraviolet light of an appropriate wavelength, such as irradiation with ultraviolet light of 200-400 nm. In this embodiment, the acrylate monomer is ethylene glycol diacrylate, and polyethylene glycol diacrylate (PEGDA) can be formed in the composition used to mold the workpiece. PEGDA has good toughness and good wear resistance. Thus, by including 15-25% of PEGDA, the composition used to mold the workpiece can give the molded workpiece a better mechanical property (described in detail later).

The composition used to form the workpiece mold further includes an oligomer, which can be a compound with a better curing rate. In this embodiment, the oligomer is bisphenol A ethoxylate diacrylate, which allows the oligomer to have higher hardness after photocuring.

The photoinitiator can absorb energy of a predetermined wavelength of ultraviolet or visible light, thereby initiating the polymerization reaction of the acrylate monomer and the oligomer to produce curing. Specifically, the photoinitiator can absorb ultraviolet light with a wavelength of 250–400 nm, or visible light with a wavelength of 400–800 nm, and can generate, for example, free radicals, cations, or anions to initiate the polymerization reaction of the acrylate monomer and the oligomer. In this embodiment, the photoinitiator is diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide.

Please refer to Figures 1 and 2. The combination of the present invention used to form a workpiece mold can be formed by additive manufacturing, such as by 3D printing, to form a workpiece mold 1. In this embodiment, the workpiece mold 1 is illustrated by taking a golf club head shell mold as an example. The workpiece mold 1 can be formed by dipping in slurry and applying sand to make the slurry adhere to the surface of the workpiece mold 1, and by sintering the slurry to solidify it to produce a one-piece molded club head shell. After pouring molten metal into the one-piece molded club head shell, a one-piece molded golf club head can be formed. For example, the composition used to form the workpiece mold can be 3D printed to form the workpiece mold 1. Thus, the workpiece mold 1, based on the component ratio of the composition used to form the workpiece mold, can have a coefficient of thermal expansion (CTE) of 121~130 ppm/℃ and a heat deflection temperature (HDT) of 46~53℃. Therefore, the workpiece mold 1 can have a coefficient of thermal expansion and heat deflection temperature similar to wax, and can reduce volume shrinkage and expansion during sintering to maintain a stable volume, thereby replacing traditional wax molds used for casting metals. Furthermore, it is worth noting that, based on measurements of the mechanical properties of the workpiece mold 1, the workpiece mold 1 has a tensile strength greater than 20 MPa and a tensile modulus greater than 1500 MPa, that is, the composition of the above-mentioned components has the function of forming a workpiece mold 1 with good strength.

In one embodiment of this case, the workpiece mold 1 comprises 15% acrylate monomer, 16.3% bisphenol A diacrylate ethoxylate and 0.8% photoinitiator by weight percentage. At this time, the workpiece mold 1 has a coefficient of thermal expansion of 121.3 ppm/℃, a heat distortion temperature of 46.7℃, a tensile strength of 21 MPa and a tensile modulus of 1516 MPa.

In another embodiment of this case, the workpiece mold 1 comprises 25% acrylate monomer, 23.7% bisphenol A diacrylate ethoxylate and 4.8% photoinitiator by weight percentage. In this case, the workpiece mold 1 has a coefficient of thermal expansion of 129.6 ppm/℃, a heat distortion temperature of 52.7℃, a tensile strength of 21 MPa and a tensile modulus of 1520 MPa.

Please refer to Figure 3, which shows a second embodiment of the workpiece mold for the rod head shell mold. The workpiece mold 2 has a crown 21, which may have an opening profile 22 to form a crown opening, allowing the crown opening to be used to attach a crown cover plate, such as a carbon fiber crown cover plate. It is worth noting that the crown opening is subjected to relatively large stress when the workpiece mold 2 is heated and undergoes thermal expansion. Therefore, when the workpiece mold 2 is sintered after slurry application and sandblasting, the crown opening is a relatively easy point to crack. Therefore, in this embodiment, the crown 21 also has a buffer portion 23, which is integrally formed and connected to the opening profile 22. That is, the buffer portion 23 is formed at the same time as the workpiece mold 2. The buffer portion 23 has at least one buffer hole 231. In this way, when the workpiece mold 2 is sintered, the aforementioned thermal expansion stress will occur at the buffer hole 231 and not at the opening profile 22. Even if the buffer hole 231 cracks, the opening profile 22 of the crown portion 21 can still remain intact.

Referring again to Figure 4, the workpiece mold 2 has a bottom 24 (Sole), which may have an opening profile 25 to form a bottom opening for use with a bottom cover plate, such as a carbon fiber bottom cover plate. Therefore, the opening profile 25 of the bottom 24 can be integrally connected to a buffer portion 26, and the buffer portion 26 has at least one buffer hole 261. This also prevents the opening profile 25 of the bottom 24 from being affected by expansion and cracking.

Thus, after forming a club head shell mold using the workpiece mold 2, pouring molten metal into the club head shell mold yields a semi-finished club head. A buffer portion for cracking is also formed at the aforementioned opening contour of the semi-finished club head. The worker can cut off the cracking buffer portion according to the opening contour to obtain the predetermined finished club head for capplate assembly. Accordingly, the workpiece mold of the second embodiment can be used to form a club head for capplate assembly.

In summary, the workpiece mold of this invention is formed by 3D printing of the composition, thus having a one-piece molding structure. This allows thermal expansion stress to occur at the buffer area rather than at the opening contour, maintaining the integrity of the opening contour. Furthermore, the workpiece mold not only maintains a coefficient of thermal expansion and thermal deformation temperature similar to workpiece molds made of wax, but also has better strength. It can replace traditional wax molds used for casting metals, thereby reducing costs and shortening the overall time for metal casting.

Although the present invention has disclosed the preferred embodiments using the foregoing examples, these are not intended to limit the present invention. Any modifications and alterations made by those skilled in the art relative to the foregoing embodiments without departing from the spirit and scope of the present invention shall still fall within the scope of the technology protected by the present invention. Therefore, the scope of protection of the present invention shall include all changes within the meaning and equivalent scope of the appended claims. Furthermore, when the foregoing embodiments can be combined, the present invention includes embodiments with any combination.

1,2: Workpiece mold; 21: Crown; 22,25: Opening contour; 23,26: Buffer section; 231,261: Buffer hole; 24: Bottom.

[Figure 1] Crown view of the club head shell mold of the first embodiment of the present invention. [Figure 2] Bottom view of the club head shell mold of the first embodiment of the present invention. [Figure 3] Crown view of the club head shell mold of the second embodiment of the present invention. [Figure 4] Bottom view of the club head shell mold of the second embodiment of the present invention.

2: Workpiece mold; 21: Crown; 22: Opening outline; 23, 26: Buffer section; 231, 261: Buffer hole

Claims (7)

A workpiece mold, which is a rod head shell mold, includes a crown having an opening profile and a cushioning portion integrally connected to the opening profile and having at least one cushioning hole. The workpiece mold is formed by 3D printing of a composition comprising 15-25% acrylate monomer, 15-25% bisphenol A diacrylate ethoxylate, and 0.5-5% photoinitiator by weight. For example, in the mold of the workpiece in claim 1, the acrylate monomer is ethylene glycol diacrylate. For example, in the workpiece mold of claim 1, the photoinitiator is diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide. As in claim 1, the workpiece mold includes a bottom having an opening profile and a buffer portion integrally connected to the opening profile, the buffer portion having at least one buffer hole. For example, the workpiece mold in Request 1, wherein the tensile strength of the workpiece mold is greater than 20 MPa. For example, the workpiece mold in Request 1, wherein the tensile modulus of the workpiece mold is greater than 1500 MPa. For example, the workpiece mold in Request 1 has a thermal expansion coefficient of 121~130ppm/℃ and a heat deformation temperature of 46~53℃.