JP6875789B2 - Continuous drilling method and continuous drilling device - Google Patents

Description

The present invention relates to a continuous drilling device at the time of manufacturing an automobile, a home electric appliance, a building structure, or the like.

As a method of forming a hole in a metal plate of an automobile, a home electric appliance, a building structure, etc., a hole punching process using a punch and a die is known. FIG. 1 is a schematic view of a general drilling device. As shown in FIG. 2, when the punch 1 moves downward toward the die 3, the work material 2 set in the die 3 is punched. At this time, the cut-off part is called a residue.
At the actual production site, the drilling process is continuously performed from 1,000 to hundreds of thousands of shots. One of the problems at this time is that the residue 10 shown in FIG. 2 sticks to the bottom surface of the punch without falling to the lower part of the die 3. As the punch rises, the residue moves to the upper surface of the die 3 (referred to as “residue rise”), which may hinder the contact between the work material 2 and the die cutting edge, resulting in poor punching.

As a method for preventing such scrap rising, it is generally practiced to provide an ejector 7 on the bottom of the punch 1 or to suck out by vacuum (Patent Document 5). In addition, a method of providing a step of pressing the planned hole punching portion in advance (Patent Document 1), a method of imparting a bead around the planned hole punching portion (Patent Document 2), and the like have been proposed. It is also common practice to provide an enlarged diameter portion on the inner surface of the die (Patent Document 3).
It has also been proposed to devise the operation of the punch 1. For example, a method of giving a slow or fast punch speed to make it difficult for the residue 10 to stick (Patent Document 4), a method of vibrating the punch at the bottom dead center position to sift off the residue 10 (Patent Document 5), and punching from the bottom dead center of the punch. There is a method (Patent Document 6) of decelerating or temporarily stopping when 1 rises to drop the residue 10.

Japanese Unexamined Patent Publication No. 2000-210727 Japanese Unexamined Patent Publication No. 2011-627 Japanese Unexamined Patent Publication No. 2002-160025 Japanese Unexamined Patent Publication No. 60-162600 Japanese Unexamined Patent Publication No. 63-130226 Japanese Unexamined Patent Publication No. 2006-289413

However, there are some problems with the above method. The costs of the methods of Patent Document 1 and Patent Document 2 increase as the number of steps increases. In the method of Patent Document 2, an unintended shape is provided in the product. In the method of Patent Document 3, when the residue 10 is clogged in a slightly parallel portion inside the die 3, the residue tends to rise. It is possible to use all the enlarged diameter parts, but in this case, the cutting edge is easily damaged and the tool life is shortened. The methods of Patent Document 4, Patent Document 5, and Patent Document 6 utilize the inertial force by changing the punching speed, but these methods also cannot sufficiently remove the residue 10.
Therefore, it is an object of the present invention to surely remove debris and realize stable continuous drilling without impairing the tool life.

In order to solve the above problems, the present inventors have conducted diligent studies and obtained the following findings.
(A) In continuous drilling, scrap rise does not occur at the initial stage, but scrap rise occurs after several hundred shots, and in some cases, several tens of shots. When the residue rises, the shape of the punch hole is distorted. From these facts, the cause of the occurrence of scrap rising was considered as follows.
It was considered that the sliding heat generated in one punching process would accumulate, the punch surface properties would deteriorate, the shape of the punched holes would be distorted, and in some cases, the punch surface would be seized. Then, it was thought that a vicious cycle would occur in which the sliding heat was further accumulated due to the deterioration of the punch surface properties and the surface properties were further deteriorated. As a result, it was considered that a part of the residue finally adhered to the punch in the relevant portion, causing the residue to rise.

(B) Therefore, the drilling process was reviewed so that sliding heat would not be accumulated in one drilling process, that is, the punch surface temperature would be lowered.
As a result, it was found that the surface temperature of the punch is lowered by temporarily stopping the movement of the punch when the punching is completed. After that, it was found that by restarting the movement of the punch again, stable punching can be performed without raising the punch temperature.
That is, it has been found that by dividing the movement of the punch in the punching process into two stages and providing a stop time in the middle, the increase in the punch temperature is suppressed, and as a result, the increase in the residue can be prevented.

(C) Furthermore, the present inventors repeated the experiment and found that the intermediate stop time should be 0.1 seconds or more.
The present invention has been made based on the above findings, and the gist thereof is as follows.

(1)
In a continuous punching method in which a die having a punch and a die is used to continuously punch a work material a plurality of times, the movement of the punch in one punching process is divided into two stages, a first stage and a second stage. As the first step, the punch is moved until the drilling of the work material is completed, then the punch is stopped, and then the punch is moved again as the second step to complete a series of punching, and this is repeated multiple times. A continuous punching method characterized by repeating.
(2)
The continuous drilling method according to (1), wherein the punching time is 0.1 seconds or more and 10 seconds or less.
(3)
The continuous punching method according to (1) or (2), wherein the movement of the punch in the first step is until the amount of overlap between the punch and the die is more than 0 mm and 2 mm or less.
(4)
The continuous drilling method according to any one of (1) to (3), wherein the moving distance of the punch in the second step is 1 mm or more and 10 mm or less.
(5)
The continuous hole punching method according to any one of (1) to (4), wherein the bottom surface of the punch is provided with an ejector capable of applying pressure to the work material.
(6)
Any one of (1) to (5), wherein the distance between the inner surface of the die and the moving center line of the punch increases in at least one portion of the inner surface of the die with respect to the moving direction of the punch. The continuous punching method described in the section.
(7)
The continuous hole punching method according to any one of (1) to (6), which is carried out by a servo press machine.
(8)
A continuous drilling device having a die having a punch and a die and a feeding device for feeding a work material into the die. The movement of the punch is divided into two stages, a first stage and a second stage, and the first stage is A continuous drilling device comprising a control device that controls the movement of the punch so as to provide a time to stop the movement of the punch between the stage and the second stage.
(9)
The continuous hole punching device according to (8), wherein the punching time is 0.1 seconds or more and 10 seconds or less.
(10)
The continuous punching device according to (8) or (9), wherein the movement of the punch in the first step is such that the amount of overlap between the punch and the die is more than 0 mm and 2 mm or less.
(11)
The continuous hole punching device according to any one of (8) to (10), wherein the moving distance of the punch in the second stage is 1 mm or more and 10 mm or less.
(12)
The continuous hole punching device according to any one of (8) to (11), wherein the bottom surface of the punch is provided with an ejector capable of applying pressure to the work material.
(13)
Any one of (8) to (12), wherein the distance between the inner surface of the die and the moving center line of the punch increases in at least one portion of the inner surface of the die with respect to the moving direction of the punch. The continuous punching device described in the section.
(14)
The continuous hole punching device according to any one of (8) to (13), which is carried out by a servo press machine.

According to the present invention, stable continuous drilling can be performed without raising the residue.

FIG. 1 is a diagram schematically showing a conventional drilling machine. FIG. 2 is a diagram schematically showing scraps when drilling is performed by a conventional drilling apparatus. FIG. 3 is a diagram schematically showing a punch with an ejector. FIG. 4 is a diagram schematically showing a die having a diameter-expanded portion on a part of the inner surface. FIG. 5 is a diagram schematically showing the die used in the second embodiment. FIG. 6 is a diagram schematically showing the punch used in the third embodiment.

The present invention will be described in detail below.
The continuous hole punching device used in the description includes a die having a hole punch 1 and a die 3, and a plate feeding device for feeding the work material 2 into the die.
Since the movement of the punch 1 in the axial direction is complicated in the present invention, it is preferable to use a servo press machine. An electric servo press is even better. It is desirable that the servo press machine is a direct acting type in order to obtain the required punching load at the bottom dead center for punching (for convenience, the position where the punch temporarily stops after punching is called the bottom dead center for punching). As the die having the hole punch 1 and the die 3, a general die for continuous hole punching is used. The plate feed device is used in conjunction with the operation of the press machine.

<Continuous drilling with conventional equipment>
When the present inventors performed continuous drilling of φ10 mm on a mild steel plate having a thickness of 1 mm with a clearance of 10% of the plate thickness of the work material using the above device, no drilling was performed for 1000 shots. I fell into a situation where the holes were poorly punched due to the rising scraps. When the residue was raised, the shape of the punched hole was significantly distorted, which was a defect as a product.
Therefore, as shown in FIG. 3, a punch 8 in which the ejector 7 was incorporated was used, but although the frequency was reduced, the residue still increased, and it was not possible to continuously punch 1000 shots.
We also considered pushing the residue into the die by setting the overlap amount 9 to about 2 mm. In this case, although the residue could be prevented from rising, the sliding distance between the punch 1 and the hole end became longer, which resulted in a longer sliding distance between the punch 1 and the hole end. Frequent seizures and frequent tool damage.
As shown in FIG. 2, the overlap amount 9 is the distance between the bottom surface of the punch and the top surface of the die when the punch 1 is inserted into the die 3.

<Continuous drilling by the device of the present invention>
[Two-step punch movement]
While the normal punching process is completed by one punch movement without stopping in the middle, the present invention divides the punch movement into two stages, a first stage and a second stage, and the punch movement is in between. Is characterized by temporarily stopping. The drilling process according to the present invention will be described below step by step.
First, the punch is moved to an initial position (referred to as top dead center in the present specification), and a work material such as a steel plate is placed between the punch and the die (usually placed on the die). At this time, the plate holder 4 may be arranged as needed.
Next, the punch is moved (first step) until the punching of the work material is completed (to the bottom dead center of the drilling). "Completed drilling of the work material" means that the residue (the part cut off by the drilling process) is completely separated from the work material. Therefore, it is necessary that at least the punch is inserted inside the die, that is, the amount of overlap is at least greater than zero.
After that, the movement of the punch is temporarily stopped (this stop position is the dead center under the hole). By this stop, the heat (sliding heat) locally accumulated on the punch surface is diffused, and the punch surface temperature can be lowered.

After that, the punch is moved again, and the punch is moved to the final stop position (referred to as bottom dead center in the present specification) (second stage). By this second step of movement, the residue is completely separated and the drilling process is completed.
The punch that has reached the bottom dead center moves to the initial position (top dead center) again, and the punched work material is removed.
The above steps are collectively referred to as a series of drilling processes in the present specification.

[Punch movement control device]
As the device according to the present invention, the conventional continuous hole punching device may have a control measure for controlling the movement of the punch. It suffices if the control device can control the movement of the first stage, the movement of the second stage, and the stop time in between.

[Amount of overlap in the first stage]
The movement of the punch in the first stage is temporarily stopped after the punch is passed through the work piece so that the overlap amount 9 is 2.0 mm or less. Here, the upper limit of 2.0 mm was found by repeated experiments because the seizure would occur if the overlap amount 9 was too large. Considering the fluctuation of the processing conditions, the upper limit of the overlap amount is preferably small, preferably 1.5 mm, and more preferably 1.0 mm. The lower limit is not particularly defined, and it is sufficient that the punch 1 penetrates the work piece 2. In that sense, the lower limit of the overlap may be larger than 0 mm (it may be more than 0). However, since a steel plate or the like has an elastic deformation region, it is preferably 10% or more of the plate thickness of the work material.

[Punch stop time]
The stop time of the punch 1 may be about 0.1 second, and the heat of the punch 1 during this stop (heat generated by sliding during drilling (the heat generated by sliding during drilling) may be referred to as “sliding heat” in the present specification. )) Conducts to the other to cool the punch. It is desirable that the punch stop time (cooling time) is long. Therefore, the lower limit of the stop time is preferably 0.5 seconds, more preferably 1.0 second.
On the other hand, according to the experiments by the inventors, if the stop time is 10 seconds, the punch is cooled to room temperature, so that it is not necessary to provide a stop time longer than this. Therefore, the upper limit of the stop time is 10 seconds.

[Movement of punch in the second stage]
After stopping, push the punch 1 about 1 to 10 mm to send the residue 10 to the back of the die 3. The lower limit of 1 mm was found by repeated experiments on the amount of pushing in which the residue was surely prevented from rising. Here, considering that seizure occurred at an overlap amount of 2 mm at the time of punching, pushing in a punch of 1 mm or more may cause punch seizure.
However, in reality, since the pressure applied to the punch is smaller than that in the case of punching, seizure did not occur even if the pushing amount was longer than 1 mm. However, when pushed in by 10 mm or more, the sliding distance becomes too long, and seizure may occur. By the continuous hole punching device that goes through these processes, it was possible to prevent the scraps from rising without shortening the life of the punch 1 due to seizure.

[Diameter inside die]
In the continuous drilling device according to the present invention, a diameter-expanded portion 12 may be provided on the inner surface of the die 3 as shown in FIG. The enlarged diameter portion does not have to be the entire inner surface of the die. That is, it is sufficient that the distance between the inner surface of the die and the moving center line of the punch increases with respect to the moving direction of the punch in at least a part of the inner surface of the die. Further, the cross-sectional shape of the inner surface of the die perpendicular to the moving center line of the punch (also the shape of the bottom surface of the punch, that is, the shape of the hole to be opened) is not limited to a circle. Even if the holes have various shapes, it is sufficient that at least a part of the inner surface thereof has an increased distance from the moving center line with respect to the moving direction of the punch. In the present specification, this portion is referred to as a "diameter expansion portion" for convenience.
Of course, the entire inner surface of the die may be an enlarged diameter portion. In that case, it is preferable to install a surface parallel to the moving center line of the punch on the upper part of the inner surface of the die (the side where the punch enters is called the upper part) instead of the enlarged diameter portion. By doing so, it is possible to avoid damage to the die end portion (the portion corresponding to the blade).
As a result, the residue 10 pushed to the enlarged diameter portion 12 falls to the lower part of the die 11 by its own weight, so that the load of the punch due to pushing the residue 10 is reduced, and the tool life can be expected to be improved. In addition, it is possible to reduce the risk of scrap rising due to scrap clogging. It is desirable that the amount of diameter expansion is small in terms of tool life. It is necessary to determine the size by trial and error by observing the punch load and the presence or absence of clogging of the residue.

[Ejecta]
Further, if the ejector 7 is provided on the bottom surface of the punch 1 (the surface in contact with the residue), the risk of the residue rising can be further reduced. The ejector is a mechanism provided on the bottom surface of the punch and presses the work material (including the residue) to facilitate the separation of the residue. The method of applying pressure is not particularly limited. Some punches have an elastic body such as a spring placed inside the punch to apply pressure to the material to be processed.

[Drilling speed and hole size]
It is also possible that the drilling speed and drilling size affect the scrap rise and punch life. In the experiments conducted by the present inventors, the punching speed was 400 mm / sec and the punching size was about φ50 mm, but the effect of the continuous punching device was obtained without any problem. Considering from the principle of the present invention, these punching speeds and punching sizes do not limit the application fields of the present invention.
Further, the present invention is not limited to the round hole, and the same effect can be obtained for an ellipse, a square hole, and any other hole shape.

An evaluation test was carried out using a 1.6 mm thick 590 MPa class steel sheet as a work material by the continuous drilling method according to the present invention and the conventional continuous drilling method (a method in which punch movement is not stopped halfway), which is a comparison target. In both the examples and the comparative examples, the drilling speed was set to 200 mm / sec, and the drilling portion was a round hole having a diameter of 10 mm. The clearance between the punch and the die was set to 10% of the plate thickness of the material to be processed. In both Examples and Comparative Examples, dies having no enlarged portion were used, and no punch ejector was used. The maximum number of shots was 30,000 shots. Table 1 shows the overlap amount at the time of punching, the punch stop time, the punch pushing amount after the stop, the number of shots in which the residue rises, and the presence / absence of punch seizure at the time of the residue rise (up to 30,000 shots).
From Table 1, in the comparative example, scrap rising occurred at 12000 times, and seizure was also confirmed. On the other hand, in all the examples of the present invention, the residue did not rise up to 20000 shots or more, and there was no seizure, or even if there was, it was observed only in a minute region. This verified the effect of the present invention.

Hole punching was performed with a die having an enlarged diameter portion on the inner surface. The drilling conditions were the same as those for A6 in Example 1 (Table 1). As shown in FIG. 5, a die having a diameter-expanded portion having an inclination angle θ with respect to the moving center line of the punch was used, and no punch ejector was used. The maximum number of shots was 30,000 shots. Table 2 shows the overlap amount at the time of punching, the punch stop time, the punch pushing amount after the stop, the number of shots in which the residue rises, and the presence / absence of punch seizure at the time of the residue rise (up to 30,000 shots).
From Table 2, by having the enlarged diameter portion on the inner surface of the die, the residue is raised by 30,000 shots and no seizure occurs. This is improved as compared with the case where the die of Example 1 has no enlarged diameter portion. This verified the effect of the present invention.

Hole punching was performed with a punch having an ejector on the bottom surface. The drilling conditions were the same as those for A2 in Example 1 (Table 1). The die used had no enlarged diameter portion, and the punch had an ejector having a diameter φ as shown in FIG. The maximum number of shots was 30,000 shots. Table 3 shows the overlap amount at the time of punching, the punch stop time, the punch pushing amount after the stop, the number of shots in which the residue rises, and the presence / absence of punch seizure at the time of the residue rise (up to 30,000 shots).
From Table 3, by providing the ejector on the bottom surface of the punch, the residue is raised by 30,000 shots and no seizure occurs. This is improved as compared with the case where the punch of Example 1 has no ejector. This verified the effect of the present invention.

The present invention can be used for drilling holes in steel sheets and the like. In particular, in continuous drilling, stable continuous operation can be realized without scrap rising.

1 Punch 2 Work material 3 Die 4 Plate retainer 5 Clearance 6 Spring 7 Ejecta 8 Punch with ejector 9 Overlap amount 10 Cass 11 Die with enlarged diameter 12 Die inner diameter enlarged 20 Punch movement center line θ Die inner surface Inclination angle of enlarged diameter φ Ejecta diameter

Claims (10)

In the continuous drilling method in which the work material is punched multiple times in succession using a die having a punch and a die, the movement of the punch from the top dead center to the bottom dead center in one drilling is the first step. If two stages of the second step, the punch from the top dead center to piercing is completed piercing bottom dead center of the workpiece moves a first step, then after stopping a punch, the second stage moving from piercing bottom dead center punch to the bottom dead center again to complete the series of piercing,
The movement of the punch in the first stage is until the amount of overlap between the punch and the die becomes more than 0 mm and 2 mm or less.
The time for stopping the punch is 0.1 seconds or more and 10 seconds or less.
The moving distance of the punch in the second stage is 1 mm or more and 10 mm or less.
A continuous drilling method characterized by repeating this multiple times. The continuous drilling method according to claim 1, wherein the amount of overlap between the punch and the die in the first step is 10% or more and 2 mm or less of the plate thickness of the material to be processed. The continuous drilling method according to claim 1 or 2, wherein the bottom surface of the punch is provided with an ejector capable of applying pressure to the work material. The method according to any one of claims 1 to 3, wherein the distance between the inner surface of the die and the moving center line of the punch increases in at least one portion of the inner surface of the die with respect to the moving direction of the punch. The described continuous punching method. The continuous hole punching method according to any one of claims 1 to 4, wherein the method is performed by a servo press machine. A continuous drilling device having a die having a punch and a die and a feeding device for feeding a work material into the die, and moving the punch from the top dead center to the bottom dead center in one drilling process. Is divided into two stages, the first stage from the top dead center to the bottom dead center for drilling where the drilling of the work material is completed, and the second stage from the bottom dead center for drilling to the bottom dead center. It has a control device that controls the movement of the punch so as to provide a time to stop the movement of the punch between the stage and the second stage.
The movement of the punch in the first stage is until the amount of overlap between the punch and the die becomes more than 0 mm and 2 mm or less.
The time for stopping the movement of the punch is 0.1 seconds or more and 10 seconds or less.
A continuous punching device characterized in that the moving distance of the punch in the second stage is 1 mm or more and 10 mm or less. The continuous drilling device according to claim 6, wherein the amount of overlap between the punch and the die in the first stage is 10% or more and 2 mm or less of the plate thickness of the material to be processed. The continuous drilling device according to claim 6 or 7, wherein the bottom surface of the punch is provided with an ejector capable of applying pressure to the material to be processed. According to any one of claims 6 to 8, the distance between the inner surface of the die and the moving center line of the punch increases in at least one portion of the inner surface of the die with respect to the moving direction of the punch. The continuous punching device described. The continuous drilling device according to any one of claims 6 to 9, wherein the continuous drilling device is carried out by a servo press machine.

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