KR20100111804A - Manufacturing method of pcd cutting tool and the pcd cutting tool - Google Patents

Abstract

PURPOSE: A manufacturing method of a polycrystalline diamond cutting tool and a PCD cutting tool thereof are provided to improve productivity by increasing the number of PCD tips from a PCD disk. CONSTITUTION: A manufacturing method of a polycrystalline diamond cutting tool is as follows. A PCD tip(11) is manufactured from the PCD disc. The PCD tip is made of a PCD layer(11a) and a base layer(11b). The PCD tip cuts the junction of a neck(12) of a cutting tool in V shape. The base layer of the PCD tip is combined with the junction of neck. The base layer is cut in V shape. The V-shape cut base layer of the PCD tip is combined with the junction of a neck. The base layer is welded by oxygen-acetylene brazing.

Description

Manufacturing method of the PCD cutting tool and the PCD cutting tool {Manufacturing method of PCD cutting tool and the PCD cutting tool}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool having a polycrystalline diamond, or PCD, as a tip. In particular, a PCD tip is manufactured from a PCD disc composed of a PCD layer and a substrate layer and bonded to a neck. A method of manufacturing a cutting tool and a PCB cutting tool thereof.

The cutting tool used herein is a name encompassing a drill, an end mill, and the like. Conventional cutting tools, such as a drill and an end mill, are made of cemented carbide, and tips of various materials are selectively used according to the material to be cut. have.

In general, diamond tips are suitable for machining non-ferrous and mineral materials, but not suitable for machining ferrous materials, cemented carbide tips have a short lifespan, and PCBN (Polycrystalline Cubic Boron Nitride) tips for processing mineral materials. There is a drawback to being inadequate.

PCD (Polycrystalline Diamond), which has recently been spotlighted as a tip material, is known to have the highest hardness, and is manufactured by sintering under conditions of high temperature and pressure using artificial diamond manufacturing techniques. PCD's excellent chemical stability makes it particularly suitable for processing non-ferrous and silicon-containing mineral materials. PCD end mills have a tool life of about 20 times that of cemented carbide end mills. It is the base material for breakthrough cutting tools.

PCD cutting tool, the tip portion is composed of PCD, the remaining shank portion is made of cemented carbide or a material having a lower strength. And, the PCD tip and bag portion are usually joined by brazing.

In the PCD cutting tool of the brazing joint type, the PCD was conventionally manufactured by brazing the neck portion, but in recent years, as illustrated in FIG. 1, the PCD layer 1a of polycrystalline diamond and mainly titanium A base layer (b) of alloy steel is fabricated by joining the PCD tip formed from the PCD disc, which is a sintered body sintered to a certain thickness, with the neck, because the neck of the PCD tip and the cemented carbide material is directly brazed. Because of poor bond strength, the base layer of the PCD tip is brazed to the neck.

The type of brazing the PCD tip to the neck is representative of a butt joint type. A single shape is shown in FIG. 2A, but an uneven shape is mainly used as shown in FIG. 2B. However, in the case of straight brazing, there is a problem in that the brazing force of the brazing portion 2a is weak. In the case of the uneven brazing, the end mill is taken from the edge of the brazing portion 2b rather than the edge of the end mill. The neck should be small, but there is a problem that it is impossible with the uneven joint structure.

Vacuum brazing and high frequency brazing are used as brazing methods for PCD tips and necks.Because both vacuum brazing and high frequency brazing use pastes as filler materials, there is a fatal problem that the bond strength of the brazed portion is weak. There is a problem that it is difficult to accurately position the brazing joint site, and it is very difficult to uniformize the temperature control.

On the other hand, another form of brazing the PCD tip to the neck is an implant joint type, which forms a deep groove in the neck region 3a, as illustrated in FIG. 3, in which the PCD tip 3b is formed. ) And then brazing. However, in the implant joint type, it is not easy to insert the PCD tip 3b straight into the groove of the neck portion 3a in a straight line. Therefore, the performance of the cutting tool may be deteriorated if the joint is inserted with a slight inclination. Not only is there a concern, the brazing joint itself is also very difficult. In addition, when manufacturing a single PCD tip from the PCD disk consisting of a PCD layer and a base layer by wire cutting discharge machining, there is a problem that not only the productivity is reduced due to the long processing time due to the thickness of the base layer, but also the product price increases. .

The present invention is to improve the conventional problems as described above, the object of the present invention is a method for manufacturing a PC cutting tool that can maintain a long bond life and excellent bonding strength to the brazed joint of the PCD tip and neck and It is to provide the PCB cutting tool.

The present invention for achieving the above object, the step of manufacturing a PCD tip consisting of a PCD layer and a base layer from a PCD disk, V-cutting the junction of the neck of the cutting tool to be bonded to the PCD tip, the PCD tip Forming a base layer of the V-cut PCD tip at the junction of the V-cut neck and oxygen-acetylene brazing bonding the base layer of the V-cut to join the joint of the neck. Provided is a method for manufacturing a cutting tool.

In the above manufacturing method, the PCD layer and the base layer may be formed in a thickness ratio of 1: 1.5 to 2, and the V cut may be formed so that the cabinet angle is 80 to 120 °.

The present invention also provides a PC cutting tool manufactured by the above manufacturing method.

According to the present invention configured as described above, there is an effect that can produce a PCD cutting tool that is excellent in bonding strength to the brazing joint of the PCD tip and the neck and also maintained a long life.

In addition, according to the present invention, the number of PCD tips that can be manufactured from PCD discs is increased compared to the conventional, and the thickness of the PCD tips is significantly smaller than that of the conventional implant joint type, etc., thereby reducing the cost and improving productivity. You can expect.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. It doesn't happen.

 4 is a view showing an embodiment of a PCD cutting tool provided by the present invention, the manufacturing method is as follows.

First, the PCD tip 11 is manufactured using the PCD disc described in FIG. 1. The PCD disc is a sintered body in which the PCD layer 11a and the base layer 11b are sintered at a constant thickness ratio. The PCD layer 11a is made of polycrystalline diamond, and the base layer 11b is mainly made of titanium alloy steel. Made of the same material. In the present invention, when the thickness ratio of the PCD layer 11a and the base layer 11b is 1: 1.5 to 2, the thickness ratio of the PCD layer 11a and the base layer 11b is smaller than 1: 1.5 or there is no base layer 11b. The brazing heat causes the PCD layer 11a to heat up when the PCD tip is brazed to the neck of the cutting tool, causing the PCD to be damaged by heat. In addition, when the thickness ratio of the PCD layer 11a and the base layer 11b is larger than 1: 2, the cost for producing the PCD disc is increased, which is not preferable. Such PCD discs are made into individual PCD tips 11 by wire cutting electrical discharge machining.

Next, in order to join the PCD tip 11 manufactured as described above to the neck 12 of the cutting tool, the V 12 of the joint 12a of the neck 12 of the cutting tool to which the PCD tip 11 is to be joined is cut. Then, the base layer 11b of the PCD tip 11 is cut V to be joined with the junction 12a of the neck 12. At this time, it is preferable that the V cut of the junction part 12a of the neck and the PCD tip base layer 11b is made so that the internal angle (theta) may be 80-120 degrees. In other words, when the cabinet angle θ is smaller than 80 °, not only the V cut is difficult but also the strength of the joining site is lowered.

Subsequently, the base layer 11b of the V-cut PCD tip 11 is joined to the junction 12a of the V-cut neck 12 and bonded by oxygen-acetylene brazing. In case of vacuum brazing or high frequency brazing, there is a limitation that the filler metal can be used as a paste because the work is done in a confined space. However, when oxygen-acetylene brazing, the filler material can be used as a silver solder rod instead of a paste. It is much better than paste filler metal. That is, the paste is a filler material is added to the flux in the form of a powder, because the density of the filler material is low, the bonding strength is lower than when using the silver solder rod itself as the filler material. In addition, in the case of vacuum brazing or high frequency brazing, bonding is performed by applying heat in an enclosed space, so that the silver solder rod cannot be directly used as a filler material.

As described above, in the present invention, since the junction 12a of the neck 12 and the base layer 11b of the PCD tip 11 are cut into V-shapes and oxygen-acetylene brazed, they are conventionally cut into a straight or uneven shape and vacuum brazed. Alternatively, as compared with the case of bonding by high frequency brazing, the strength of the joint is greatly improved and stable bonding can be seen.

As mentioned earlier, when brazing with oxygen-acetylene, the silver lead rod can be used as a filler metal, so that the strength of the bonding site can be improved, the brazing can be performed at the correct position, and the temperature can be easily controlled around 680 ° C. Has the advantage.

In the case of oxygen-acetylene brazing for the V-cut joint, the number of PCD tips that can be fabricated from the same size PCD disks is also increased compared to the prior art, which can greatly contribute to cost reduction. That is, in the conventional case of brazing the joint portion of the neck and the PCD tip into an uneven shape, a subsequent step of polishing the PCD tip is required after brazing, so that the size of the PCD tip before the polishing process is about twice as large as the final size. It should be made larger. Therefore, the number of PCD tips that can be produced from the same size of PCD disks can only be small, considering that the price of the PCD disk is expensive it can be seen that the manufacturing method according to the present invention is very economical.

For example, when manufacturing a PCD tip using a PCD disc having a diameter of 60 mm, when the PCD tip and the neck have a straight joint, as many as 120 PCD tips can be produced regardless of the diameter. If the neck is a concave-convex type, about 120 to 400 PCD tips may be manufactured depending on the diameter of the PCD tip. On the contrary, in the case where the junction portion of the PCD tip and the neck is V-cutted as in the present invention, about 120 to 1000 PCD tips may be manufactured according to the diameter of the PCD tip. Assuming that the diameter of the PCD disk is the same, the number of PCD tips that can be manufactured from one PCD disk is 800% or more, compared to the straight brazing joint in the V-cut brazing joint, as shown in the present invention. It can be seen that the effect is increased by more than 200%. This is because in the case of straight or uneven brazing, vacuum brazing or high frequency brazing is performed, so that the amount of post-processing is increased compared to oxygen-acetylene brazing in the V-cut brazing joint like the present invention.

Therefore, when the PCD tip and the neck joint are manufactured in V-cut form and the oxygen-acetylene brazing is performed, vacuum brazing or high frequency brazing is conventionally performed by making the PCD tip and the neck joint part straight or uneven. Compared to this, the cost savings are superior.

In the above described the present invention based on the preferred embodiment, the present invention is not limited to the above embodiment, various modifications by those skilled in the art within the scope of the technical idea of the present invention This is possible.

1 is a perspective view showing a PCD disk required for the production of a PCD tip.

Figure 2a is a view showing an example of the conventional brazing bonded PCD tip to the neck.

Figure 2b is a diagram showing an example of conventional brazing bonded PCD tip to the neck.

Figure 3 is a view showing an example of a cutting tool conventionally implanted PCD tip to the neck.

Figure 4 is a view showing an example of a cutting tool oxygen-acetylene brazed V-cut joint of the PCD tip and neck in accordance with the present invention.

<Explanation of symbols for the main parts of the drawings>

11: PCD Tip 11a: PCD Layer

11b: base layer 12: neck

12a: junction

Claims (4)

Manufacturing a PCD tip comprising a PCD layer and a base layer from the PCD disc; V-cutting the joint of the neck of the cutting tool to which the PCD tip is to be joined; V-cutting the base layer of the PCD tip to fit the junction of the neck; And joining the base layer of the V-cut PCD tip to the junction of the V-cut neck to form an oxygen-acetylene brazing joint. The method of claim 1, And forming a PCD layer and a base layer in a thickness ratio of 1: 1.5 to 2. The method of claim 1, And the V cut is formed such that the angle is 80 to 120 degrees. A cutting tool manufactured by the manufacturing method of any one of claims 1 to 3.

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