JPS6355410B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for drilling a stainless steel eyeless suture needle that cannot be hardened by quenching, and more specifically, the needle material is work-hardened by wire drawing at a high processing rate. At the same time, the crystal grains of the needle material are made into a drawn structure elongated in the longitudinal direction of the needle, and then the perforated portion of the needle material is heated to make the crystal grains into a non-elongated structure and softened. The needle material is gripped with the opening portion protruding from the rotary chuck, the needle material is rotated, and a cutting agent is applied to the protruding portion of the needle material and the drill while drilling a hole in the end surface of the needle material with the drill. The present invention relates to a method of manufacturing a stainless steel eyeless suture needle that cannot be quenched.

There are two main types of stainless steel suture needle materials used based on metallurgy. One type is stainless steel that can be quenched and hardened, such as 13Cr stainless steel, which was mainly used until the 1960s and is still the mainstream in Europe and the United States. It is a stainless steel that cannot be quench hardened, typified by the austenitic stainless steel that has been used for a long time and is hardened through work hardening and precipitation hardening. The former is processed to an appropriate degree of softness and then quenched and hardened in the final stage, while the latter is mainly work-hardened by wire drawing and further hardened by precipitation. After the wire drawing process, the wire is processed without lowering its hardness, and finally it is hardened to some extent by a folding process or a taper process.

The manufacturing method of the present invention is for the latter type of stainless steel that cannot be hardened by quenching, and representative examples of steel types include SUS304, SUS302, SUS63151, etc.

In addition, drilling, laser processing,
Various methods are used to perform this, including electron beam machining and electrical discharge machining, among which drilling is generally used when drilling relatively large holes with a diameter of 0.3 mm or more due to machining accuracy and cost considerations. To perform this drilling process, in order to drill a relatively large hole with an inner diameter of approximately 1/2 to 2/3 of the diameter of a small diameter needle, hold the drilled part of the needle completely, and It is necessary to provide rigidity to the needle, and for this reason, conventionally, the needle material 2 is inserted into the hole 3 of the fixed chuck 1, as shown in FIG. 1A.
Either embed the entire hole and drill the hole while rotating the drill 4 and applying cutting fluid (cutting oil or cutting fluid), or in order to mass produce it, install it in a split chuck 1' as shown in Figure 1B. The needle material 2 was completely embedded in the needle material holding hole 3', and in this state, the drill 4 was rotated to drill holes in the needle material 2 one after another. According to this method, since the punched part of the needle material 2 is fully gripped by the chucks 1 and 1', the rigidity of this part can be increased, and the end surface of the needle material 2 and the chuck 1 and 1' surfaces are the same. Since it is a flat surface, there is an advantage that the cutting agent easily enters the machined hole when the drill 4 is removed from the machined hole. Therefore, it has become common sense to use the above method for drilling.

In addition, in the above method, as shown in Figure 2A in terms of metallographic structure, the drawing structure itself of hard and elongated crystal grains is removed, but the reason for this is firstly that the hole punched by the needle is highly rigid. Second, as mentioned above, the hole diameter is 1/2 to 2/3 of the needle material diameter. The thickness is 0.125mm, which is very thin.
In order to resist the chuck force with this thin wall, it is better to be hard, and thirdly, because the drawn wire structure is hard and long in the length direction of the needle material, is strong but brittle in the diameter direction, and when this is drilled, the shavings become brittle in the length direction, and the shavings are cut short and the shavings are drilled.
For reasons such as not getting entangled with the wire, the hard drawn wire structure was scraped off.

However, the above method had the following disadvantages.The first disadvantage is that the cutting debris is short and does not get entangled with the drill 4, but on the other hand, when the hole deepens to a certain extent as the cutting progresses, it may cause damage inside the drill groove. Chips get stuck in the
This may cause the drill to break. In addition, in order to increase the rigidity, the needle material 2 is chucked all the way to the hole part.
Since the cutting agent is buried in the needle material 1', the cutting agent is applied only to the end surface of the needle material 2, and not to the side surface.
Therefore, in order to cool the needle material 2 and drill 4, introduce cutting agent to the drill cutting edge, and remove cutting waste from the drill groove, so-called step processing must be performed in which the drill 4 is pulled back and inserted and cut again. However, in step machining, the machining time becomes longer and the wear of the drill cutting edge increases because the drill tip is most worn when it first comes into contact with the material. The second drawback is that since the drill 4 is rotated for cutting, the machined hole tends to shift from the center as the cutting progresses. i.e. drill 4
If the center of the needle material 2 coincides with the center of the needle material 2, the hole will be drilled at the center of the needle material 2 near the entrance of the machined hole. If a deviation occurs, the hole will continue to shift in that direction, and since the wall thickness is very thin when drilling with an eyeless needle, the drill 4 will penetrate through the wall and hit the chucks 1 and 1', causing the drill to break. becomes. Furthermore, the third drawback is that in order to increase the rigidity of the needle material 2, the entire needle material is buried in the chucks 1 and 1', so if a misalignment occurs in the machined hole, the chuck will be damaged due to the thin wall thickness. The tightening pressure causes the hole wall to deform inward, tightening the drill 4 and causing the drill to break.

The present invention is a technology developed in view of the above-mentioned drawbacks of the conventional technology, and its purpose is to heat and soften the perforated part of the needle material in the hard drawn wire structure to create a normal structure. By providing a drilling method that is completely opposite to conventional common sense, the drawbacks of conventional processing methods can be fundamentally solved. This is an improvement.

An embodiment of the present invention will be described with reference to the drawings. First, a stainless steel wire rod that cannot be quenched and hardened to become an eyeless needle is drawn by increasing the reduction (area reduction rate, processing rate). For example diameter 1.6
The wire rod 6 having a diameter of 1.5 mm is heated to about 1100° C. and subjected to solution heat treatment to soften it into a structure in which the crystal grains are not elongated as shown in FIG. 2B. Next, the wire is cold-drawn to a diameter of 0.7 mm at once using several stages of dies 5 as shown in Fig. 3 without any heat treatment in between, and is greatly work-hardened by inducing worked martensite. A drawn structure (fibrous structure) having extremely elongated crystal grains in the length direction is formed as shown in FIG. 2A.
At this time, the reduction in cross-sectional area before and after wire drawing is (πD ² /4−πd ² /4)/(πD ² /4), 81
%. This work-hardened wire rod 6' of drawn wire structure is particularly strong in the length direction and is very suitable as a suture needle material.This wire rod 6' is cut to an appropriate length and the tip is sharpened. This constitutes the needle material 7. Next, as shown in FIG. 4, a flame is blown onto the perforated portion 8 of the needle material 7 using a burner 9, etc., and the portion 8 is heated and softened into a general structure with non-elongated crystal grains as shown in FIG. 2B. let That is, the needle material 7 has a general structure in which only the perforated part 8 has a softness of about Hv180 to 230 and has not long crystal grains as shown in FIG.
It has a hardness of about ~550, is strong, and has a drawn structure with extremely elongated crystal grains in the length direction of the needle as shown in FIG. 2A.

To drill holes in the needle material 7 constructed as described above, for example, a device as shown in FIG. 5 is used. This is constructed so that the needle material 7 can be gripped by a chuck 11 integrated with the sleeve 10, and the chuck 11 is constructed so that it can rotate at high speed while gripping the needle material 7 and at the same time move forward in the direction of the arrow. has been done. Further, a drill 12 for drilling holes is fixed on the axial extension line of the chuck 11, and a cutting agent injection nozzle 13 is provided at the top of the tip of the drill 12, and cutting agent is sprayed from the nozzle 13. It is configured so that it can be used. Next, to explain the case of making a hole in the end face of the needle material 7 using the above-mentioned device, first, the needle material 7 is held in the chuck 11 with the perforation part 8 protruding as shown in FIG.
In this state, rotate the chuck 11 at high speed and
The end face of the needle material is subjected to center massaging, and as shown in FIG. 7, a cutting agent is sprayed from a nozzle 13, and the chuck 11 is advanced to press the end face of the needle material against a drill 13 to make a hole.

To explain about the center kneading during the above-mentioned processing, when the drilling end face is inclined as shown in Figure 8A, if you drill directly with a drill without center kneading, the drill tip will flow because the drill is thin and easy to bend. Since the cut is made at position 14 off-center and the needle material 7 further rotates, the drill 12 is shaken, causing the drill to break. On the other hand, if you use a highly rigid center kneading tool, you will be able to perform kneading correctly at the center 15 without the tool drifting, and if you drill afterwards, you will be able to drill a hole in the correct position following the kneading process. The drill also lasts a long time.

However, even if center massaging is performed, if the needle material is completely buried in the chuck as in the conventional method,
Alternatively, if the hole portion 8 protrudes from the chuck but still has high rigidity as a hard drawn wire tissue, the center kneading tool is misaligned with the center of rotation of the needle material, as shown in Figure 8B. As if it were a W-shaped center hole, a crest would remain in the center, and if the hole is drilled in this condition, the tip of the drill would rub against the ridge, accelerating wear, and the drill 12 would swing due to misalignment, causing the drill to break. Become. On the other hand, as in the present invention, the needle material 7
If the perforated portion 8 of the needle is softened so that it protrudes from the chuck 11, the needle can be moved so that the position of the kneading tool becomes the center of rotation as shown in Fig. 8C, even if the center kneading position is slightly off. The drilled part 8 of the material 7 does not bend and rotate to form a W-shaped center hole. Furthermore, when a drill is inserted into the kneading hole, since the drilled portion 8 is soft, the portion 8 flexes and rotates in accordance with the drill, thereby preventing the drill from breaking. As the drill 12 further cuts, the cutting edge of the drill 12 moves toward the center of rotation of the needle material 7, where the force received by the rotation of the needle material 7 becomes smaller. This is advantageous because the present invention rotates the needle 7 instead of rotating the drill 12.

Next, to explain the cooling and lubrication conditions during drilling, if the drill is rotating at high speed like in the past, even if the cutting agent adheres to the drill, it will scatter due to the circular force, and due to the structure of the drill groove. However, in the present invention, since the drill 12 is stationary, the cutting agent does not scatter and is also introduced into the machined hole from the drill groove. Note that during cutting, cutting debris runs inside the drill groove, but the area occupied by the cutting debris in the groove is approximately 20 to 40 mm.
%, it can be sufficiently introduced into the machined hole from the remaining gap. In addition, in the present invention, the hole wall 8 is rotated so as to protrude from the chuck 11, and the hole wall is formed by making a hole with a diameter of 1/2 to 2/3 of the diameter of the fine needle material 7. Since it is thin, it can be evenly and effectively cooled even from the outside by the cutting agent ejected from the nozzle 13. This is a particularly effective cooling method only when drilling eyeless needles.

Next, I will explain the state of the cutting chips. This also greatly affects the life of the drill, but in the case of the present invention, the drilled part 8 is not a drawn structure, but a general structure, and is soft and has high ductility. , and because the material is sticky, the cutting chips come out in long chains. Even if long pieces of debris come out, the drill 12 is stationary in the present invention, so the pieces are removed from the drill 1.
There is no risk of it getting tangled with 2, and on the contrary, if the machined hole becomes deep, it has the advantage that it will not become clogged like short pieces of debris.

Next, I will explain the condition of the hole wall during machining.
Normally, when drilling a hole in an eyeless suture needle, the hole wall near the drill tip and the hole wall will form due to the drill tip and the built-up cutting edge that is formed when the material to be cut adheres to the drill tip. At the same time, the diameter increases due to thermal expansion, and as a practical matter, the diameter becomes larger due to thermal expansion.
It has been confirmed that the outer diameter increases by approximately 10 microns. In this case, if the drilling part is entirely held down by the chuck as in the past, the increase in the outer diameter of the needle material is limited, and as a result, strain is placed on the drill, which shortens the life of the drill. The wall that had been carved further shrunk inward, pressing down on the drill. In this case, since the drill is a tool that cuts at the tip and can hardly cut the outer periphery, it may cause the drill to break. On the other hand, in the case of the present invention, since the drilling part is free, the drill 1
2 is not pressed down and the drilled portion can expand outward, so no load is placed on the drill 12.

As explained above, the present invention eliminates the need for conventional step machining in terms of cooling conditions, lubrication conditions, and cutting debris conditions.

In the above embodiment, the perforated portion 8 was heated by the burner 9, but it may also be heated by a high frequency induction heating method or an electrical heating method.
Alternatively, the hole may be drilled by moving the drill 12 without moving the chuck 11 forward. Further, in the above embodiments, center rubbing was performed prior to drilling, but if the punched end surface of the needle material is perpendicular to the axis, center rubbing is not necessary. Furthermore, although the tip of the needle material 7 was sharpened before drilling, this may also be done after drilling.Furthermore, the wire material 6' can also be cut to a predetermined length after drilling. But it's okay.

Here, a drill with a diameter of 0.46 mm is used for a needle with a diameter of 0.75 mm, the relative rotational speed between the needle and the drill at that time is 4000 rpm, the cutting agent is white kerosene containing a rust preventive agent, and the cutting speed is 0.5 The results of an experiment conducted using a conventional method and a method according to the present invention to determine how many needles can be drilled before one drill breaks when drilling a hole to a depth of 1.7 mm using mm/S. show.

Experiment 1 (Conventional method) Condition A Drilled part Hard drawn wire structure B Chuck method Fully buried in the chuck C Rotation and steps Drill rotation, needle material fixed, steps every 0.3 mm Results: 1st run: 429 wires 2nd time: 113 wires 3rd drill 13 4th drill 42 5th drill 281 Findings The second and fourth drills broke due to bent holes.

Experiment 2 (softening of the needle material using the conventional method) Condition A: Drilling area: Soft general tissue B: Chuck method: Fully buried in the chuck C: Rotation and steps: Rotating the drill, fixing the needle material, and stepping every 0.3 mm Results: 1st time 2 pieces 2 0th time 0th time 3rd time 0th time 4th time 12th time 5th time 0th time Findings All 5 times broke after cutting more than 1mm. It appears that the inside of the wall was mostly deformed, but there was also some tangles of cutting debris.

Experiment 3 (Protruding from the chuck using the conventional method) Condition A Drilled part: Hard drawn wire structure B: Chuck method: Protruding from the chuck 2.0 mm C. Rotation and steps Drill rotation, needle material fixed, steps every 0.3 mm Results: 1st run 32 wires 2nd time: 0 pieces 3rd time: 41 pieces 4th time: 8 pieces 5th time: 16 pieces Findings Many of the drill holes were bent and the drill tip protruded to the side.

Experiment 4 (drill fixed using conventional method) Condition A Drilled part Hard drawn wire structure B Chuck method Fully buried in chuck C Rotation and step Needle rotation, drill fixed, no step Results 1st time 12 wires 2nd time 29 wires 3 6th time 4th time 18 times 5th time 23 times Findings Some drill bits were clogged with cutting chips and some had discolored drill bits.

Experiment 5 (method of the present invention) Condition A Drilled part Soft general tissue B Chuck method Protruding from 2.0mm chuck C Rotation and steps Rotation of needle material, fixed drill, no step Results 1st time 1836 pieces 2nd time 5000 pieces 3rd time 2377 Book 4th time: 981 books 5th time: 1567 items Observations The outer diameter of the hole made by the drill was 20 microns thicker the second time, so I replaced it with a new drill before it broke and did the third time.

Experiment 6 (Hard tissue using the method of the present invention) Condition A Drilled part: Hard drawn wire tissue B: Chuck method: Protruding from 2.0 mm chuck C: Rotation and step: Needle material rotation, drill fixed, no step Results: 1st run 38 wires 2nd run 105 3rd time: 18 pieces 4th time: 7 pieces 5th time: 21 pieces Findings Clogging of cutting waste was observed, and in many cases the drill was being shaken during cutting.

Experiment 7 (Needle material is buried in the chuck using the method of the present invention) Condition A: Drilled part Soft general tissue B: Chuck method: Fully buried in the chuck C: Rotation and step: Needle material rotation, drill fixation, no step Results: 1st time 3 needles 2nd time: 1 piece 3rd time: 7 pieces 4th time: 0 pieces 5th time: 1 piece Findings The cause of the drill breakage seems to be the pressure on the hole wall by the chuck.

Experiment 8 (Drill rotation using the method of the present invention) Condition A Drilled part Soft general tissue B Chuck method 2.0mm protrusion C Rotation and step Drill rotation, needle material fixed, no step Results 1st time 18 pieces 2nd time 32 pieces 3rd time 21 pieces 4th time 67 pieces 5th time 38 pieces Findings Discoloration of the tip of the drill was observed. In addition, entanglement of cutting chips was noticeable.

Experiment 9 When the needle material was rotated at 3500 rpm and the drill was rotated at 500 rpm using the method of the present invention, an average of about 1800 holes could be drilled.

Experiment 10 When drilling was performed using the method of the present invention without applying a cutting agent, the drill broke after drilling 10 holes or less in all five attempts.

As is clear from the above experimental results, the life of the drill can be significantly extended by drilling according to the method of the present invention. shall be. The perforated portion 8 protrudes from the chuck 11 and is gripped. Rotate the needle material 7. Drill holes while applying cutting fluid. It has been found that the desired effect cannot be obtained if even one of these conditions is lacking.

Since the processing method according to the present invention has the above-mentioned configuration, it is possible to apply the cutting agent evenly to the drilled part, and this also provides a cooling effect, which significantly extends the life of the drill. Furthermore, the cutting agent can also enter into the machined hole through the drill groove. In addition, even when drilling a large hole close to the diameter of the needle material, the outer diameter of the hole being drilled can swell outwards to some extent, so the drill is not tightened by wall pressure and there is no stress on the drill. The life of the drill can be extended in this respect as well, and the cutting debris does not get tangled with the drill and can be discharged while being connected for a long time. There is no need to perform this process at all, and therefore the machining time can be significantly shortened. In addition, since the drilling part is softened and free, even if the center kneading tool and drill are slightly off the axis, the needle material will flex and rotate, and the drill will not break. As the machining progresses due to rotation, the machined hole also moves closer to the center. In addition, the main body of the resulting eyeless suture needle is made of strong elongated tissue, and the hole is made of soft general tissue, so although it is a hard and strong needle, it has good thread crimping performance, and it also has a hole depth that is difficult to achieve in conventional methods. It has features such as no chipping from the edges and significantly improved quality.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the conventional drilling method, Figure 2 A is a wire drawing organization chart, B is a general organization chart, Figure 3 is an explanatory diagram of wire drawing, and Figures 4 to 7 are related to the present invention. An explanatory diagram of the processing method, FIG. 8 is an explanatory diagram of center rubbing. 1, 1', 11 are chucks, 2, 7 are needle materials, 4,
12 is a drill, 5 is a die, 6 and 6' are wire rods, 8
9 is a burner, and 13 is a nozzle.

Claims (1)

[Claims] 1. Work-harden the needle material by wire drawing at a high processing rate, and make the crystal grains of the needle material elongated in the longitudinal direction of the needle, and then heat the perforated portion of the needle material. The crystal grains are softened as they form a non-elongated structure, and the drilled part of this needle material is held so as to protrude from the rotary chuck, and while the needle material is rotated, a cutting agent is applied to the protruding part of the needle material and the drill. A method of processing a stainless steel eyeless suture needle that cannot be hardened by quenching, characterized by drilling a hole in the end face of the needle material with a drill while hanging the needle.