JPH0215844A - Method for detecting flaws in cold working - Google Patents

Abstract

PURPOSE:To precisely and quickly detect flaws such as cracks of a material to be worked on-line by arranging a crack-detecting sensor between heading stages by a cold header. CONSTITUTION:In a cold header device, crack-detecting sensors 41, 41 are arranged in each heading stage, for example, between stages 3B and 3C and after the final stage 3E. The crack-detecting sensor 41 is composed of a coil L and a power source to supply alternating current (f) to this coil and a deformed material 10 of a material to be worked is charged into the coil L in time of a measurement. When the alternating current is conducted into the coil L, a magnetic field HP is generated and a secondary magnetic field HS appears as soon as an excess current is induced in the material. For this reason, the impedance of the coil is changed and when the terminal voltage of the coil L is checked, the change and capacity of the excess current can be known. In other words, the stock (material to be worked) containing more flaws such as cracks etc., than regular stock can be detected.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a method for automatically detecting defects such as cracks that occur in a workpiece during cold processing in which bolts and the like are sequentially cold-formed. The present invention relates to a method for detecting flaws in cold working that can be performed.

[Conventional technology]

It is well known that when a workpiece is cold forged and plastically deformed, work hardening and strain hardening occur.

Incidentally, even if the above-mentioned workpiece materials have almost the same composition, their cold workability may differ depending on the conditions in the manufacturing process such as rolling heat treatment, such as when their lofts differ. Therefore, when a workpiece is sequentially subjected to restraint upsetting using a cold header, the workpiece may sometimes develop defects such as cracks.

Therefore, conventionally, defects such as cracks have been detected in the final processed product. This detection is difficult because a huge number of processed products are produced at a production rate of, for example, 100 pieces per minute.
This was mainly done through sampling and inspection.

〔Problems to be solved〕

However, such conventional inspection methods may be incomplete due to being a sampling inspection. In addition, when performing a complete inspection, the inspection itself requires a very long time.

In view of this problem, the present invention is aimed at during the forging process of restraining and upsetting the workpiece using a cold header, that is, online.

Defects such as υ1 cracks can be detected easily and quickly with high accuracy. This paper attempts to provide a method for detecting flaws in cold working.

[Means for solving problems]

In the present invention, when a workpiece is supplied to a cold nodder and subjected to sequential restraint upsetting processing, a two-break detection sensor is disposed during the forging process of the cold header, and the crack detection sensor is used to detect the crack during the processing process. A flaw detection method in cold working is characterized by detecting a workpiece in which a crack has occurred.

In the present invention, the workpiece refers to a metal material that has been processed into a coil or bar material by rolling.

Further, as a halving detection sensor, there is an eddy current flaw detector that uses magnetic flux. In this eddy current flaw detection method, as shown in Figure 2, when a coil carrying an alternating current is brought close to the workpiece, the
When there is a flaw such as a crack, the current and voltage induced in the coil change, which is used to detect the flaw. The eddy current flaw detection method is.

This is also called the magnetic induction deep wound method.

In addition to the above-mentioned eddy current flaw detection method, there is also a leakage magnetic flux deep flaw method as a method using IF flux. This method is a flaw detection method in which magnetic flux leaking from surface flaws or the like when a ferromagnetic material is magnetized is detected using a magnetically sensitive element such as a Hall element or a magnetic diode.

Therefore, the above-mentioned crack detection sensor is applied to a workpiece that is sequentially processed through five cold working processes.

This detects flaws such as 8 cracks. Therefore, as shown in FIG. 1, the crack detection sensor is placed at an appropriate location during the cold heading process, that is, online. For example, as shown in the figure, between the second and third punch,
After the final punch, that is, after the final processing, etc. Also 5
It is preferable to arrange it at least after the forging step in which the maximum processing rate is performed. Furthermore, when testing five workpieces to see which forging process they are likely to crack, etc., they may be placed between each punch.

Further, a workpiece detected by the crack detection sensor as having a crack or other flaw may not be sent to the next forging process, but may be discharged outside the process. Or,
Defective products are marked with a red mark, etc.

[For production]

In the present invention, as shown in FIGS. 4a to 4e, first, the material l as the workpiece is changed by a predetermined change amount (for example,
Upset to 30% pressure (1Iil).

0, which becomes the first deformable material 11, is then upset to a predetermined deformation setting amount (for example, 60% pressure 1 ft) in a second forging process, and becomes the second deformable material 12. Thereafter, the deformed materials 13 and 14 are sequentially processed in the same manner, resulting in the deformed materials 14 of 5 Saihiragi. According to one aspect of the present invention, a crack detection sensor is provided during the forging process on-line to measure the presence or absence of flaws in the workpiece.

[Effects] According to the present invention, defects such as cracks in corrugated material can be measured during the two cold working steps or during online cold working such as the final step. Moreover, according to the present invention, it is possible to detect flaws on all the workpieces during the processing process, with high accuracy. Therefore, process control in cold working becomes easier, and productivity improves.

Also, is that why it is conventional? 1. No complicated detection work is required.

Therefore, according to the present invention, it is possible to provide a flaw detection method in cold working that can detect flaws such as cracks with high accuracy, simply and quickly.

〔Example〕

In this example, in the cold header device shown in FIG.
The purpose is to detect the presence or absence of flaws such as 5 cracks during the upsetting process and at the final stage.

That is, the cold header is composed of an upper die part and a lower die part, and the upper die part supports the punch 3 supported by the punch holder 32.
It has 3. In addition, the lower mold part includes a die 34, a non-kout pin 36 provided below it, and an intermediate non-kout pin 37.
and has. In the figure, 31 and 38 are spacers, and 30 and pins 35 are die holders.

The cold header in this example consists of five forging machines 3A to 3E, and the material upset in each forging process is the first deformed material 11. Second deformable material 12...5th
A deformed material 15 is obtained.

Therefore, in this example, the one-break detection sensors 41 and 41 are arranged after the 3B process, the 30th process, and the final 3E process. As shown in FIG. 2, the crack detection sensor 41 includes a coil L and an alternating current f (Hz).
) and more. In the measurement, a deformable material 10, which is a workpiece, is put into the coil L.

As a result, an induced current called an eddy current is generated inside the metal material, which is the workpiece, through the alternating magnetic field generated by the coil. The distribution of this eddy current and the magnitude of the current vary depending on the shape and size of the coil, the frequency, the electrical conductivity of the metal, the magnetic permeability, and flaws in the material.

That is, as shown in Figure 2, when an alternating current of f (H2) is passed through the coil, a magnetic field of Hp is generated, which induces the above-mentioned eddy current inside the material, and at the same time, this eddy current causes secondary In this case, since Hs is in the opposite direction to Hp and acts in the direction of decreasing Hp, it becomes a kind of resistance to the initial alternating current.
By acting, the impedance of the coil changes each time. Therefore, by checking the terminal voltage of the coil L, it is possible to know the change and magnitude of the eddy current.

In other words, a material with 1 crack etc. compared to the normal material (?!a
! Processed materials) can be detected.

The crack detection sensor is electrically connected to the flaw detection device 5 as shown in FIG.

The basic circuit of the flaw detection device 5 is shown in FIG. That is, the output of the change and magnitude of the eddy current generated in the crack detection sensor 41 is sent to the automatic balancer 531 via the bridge 53. The automatic balancer 531 is adjusted in advance so that the output in the case of no defects is O. The meter 54 is used for this observation.

The output signal from the automatic balancer 531 enters the detector 55 via the amplifier 532, and the input signal is phase-analyzed by the control signal applied from the polyphaser 52 to suppress and detect noise other than the flaw signal. The results are displayed on the cathode ray tube 541. Furthermore, the filter 56 performs frequency analysis, and the rejection 58 performs amplitude analysis to remove noise other than flaws. After this, the signal is transferred to the external device 581, such as a recording device 8, a sorting device, a marker, etc. Furthermore, it is sent to the alarm device 582.

In the two examples, detection is performed as described above between steps 3B and 30. To detect the second deformed material 12 after the 3B process, the second deformed material 12 is placed into the crack detection sensor 41. After the detection, the second deformable material 12 is taken out from inside the crack detection sensor 41 and the 3C
Send to the process.

During this inspection, if it is detected that the second deformable material 12 has a flaw, the second deformable material 12 is not sent to the 3C process but is discarded as a defective product. Alternatively, mark the product with a defective product mark such as red. The same applies to the inspection in the 3E process.

As is known from the above, according to this example, it is possible to detect the presence of flaws when processing the material during the on-line upsetting process in the factory. Therefore,
If desired, this detection can be performed on a huge number of bottles, such as thousands to tens of thousands of bottles, at any time, and flaws such as cracks in cold-worked products can be detected with high accuracy.

[Brief explanation of the drawing]

Figures 1 to 3 show embodiments of the present invention, and the first one is υj
Conceptual diagram of a cold hander equipped with a detection sensor.
FIG. 2 is an explanatory diagram of the principle of the crack detection sensor, and FIG. 3 is a circuit diagram of the flaw detection device. FIGS. 4a to 40 are explanatory diagrams of the upsetting process. l O~1 3A~3 33 ・ ・ 34 ・ ・ 4 l ・ ・ 5 ・ ・ Material. 5...Deformed material E...Heading process/punch.・Dice/υ1 crack detection sensor/flaw detection device. Figure 2 Figure 3 Figure 4a Figure 4b Figure 4c Figure 4-d Figure 13\==Co-e Figure 141.1

Claims (1)

[Claims] When the workpiece is supplied to the cold header and subjected to sequential restraint upsetting, a crack detection sensor is installed during the forging process of the cold header, and the crack detection sensor detects the workpiece that has cracked during the processing process. A flaw detection method in cold working characterized by detecting a workpiece.