JPH0661676B2 - Life detection device for drilling tools - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a life detecting device for a drilling tool for forming a predetermined hole in a work.

(Prior Art) In a machine tool that repeatedly drills holes according to a predetermined program, it is desirable to accurately detect the life of the drilling tool during actual operation.

As a device related to this, conventionally, in actual operation, the load applied to the processing tool is detected with time, and a tool abnormality signal is output when the detected load deviates from the set allowable range. Is known (Japanese Patent Laid-Open No. 58-1969).
54 publication).

(Problems to be Solved by the Invention) However, when the above-mentioned conventional apparatus is applied to the detection of the life of a drilling tool, there is a problem in accuracy.

That is, when the conventional device is applied to the detection of the tool life of the drilling tool, the tool life is determined by whether or not the upper limit load value that defines the above setting allowable range is exceeded. This often includes variations, which makes it erroneously determined that the drilling tool has reached the end of its life even when the load applied to the drilling tool exceeds the upper limit load value above due to variations in the hardness of the workpiece. May be done.

The present invention has been made in consideration of the above points, and an object of the present invention is to provide a life detecting device for a drilling tool, which is capable of accurately detecting the life of the drilling tool.

(Means and Actions for Solving Problems) In order to achieve the above object, according to the present invention, a load detecting means for detecting a load applied to a drill as a drilling tool, and a load from the load detecting means. Receiving a signal, comparing means for comparing an actual amplitude based on a load signal within a predetermined period after a lapse of a predetermined time after the start of machining of the drill with a preset reference amplitude, and receiving a signal from the comparing means, When the actual amplitude is larger than the reference amplitude, an output means for outputting a tool life determination signal is provided, and a life tool detecting device for a drilling tool is provided.

With the above configuration, in continuous cutting with a drill, the life span of a drill as a drilling tool is detected based on the load fluctuation range by utilizing the phenomenon that the fluctuation range of the load applied to the drill increases as the tool life approaches. You will be able to do it.

Moreover, since the actual amplitude is based on the load signal within the predetermined period after the lapse of a predetermined time after the start of drilling, a large fluctuation range can be used as the actual amplitude, and the drill life can be accurately determined. Will be high.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. In this example, an elongated hole such as an oil hole (processing length is 1 or 5 times the processing diameter is formed in an engine part (casting product)). The above is applied to an NC machine tool that is repeatedly drilled according to a predetermined program.

FIG. 1 shows the overall configuration of the embodiment. A drill tool life detecting device A includes a load detecting means 2 for detecting a load applied to a drill 1, an amplifier for amplifying a load signal from the load detecting means, and It is composed of a low-pass filter 3, an A / D converter 4 for converting the load signal into a digital signal, and a microcomputer 5. The load detecting means 2 applies to the drill 1 from the spindle current value of the drill driving motor. It is supposed to detect a rotational load (hereinafter referred to as torque). In the microcomputer 5, each time the workpiece is processed,
Based on the amplitude of the load signal, in other words, based on the torque fluctuation width, the life of the drill 1 is determined, and when it is determined that the drill 1 is at the end of life, a life warning signal is output and the warning lamp 6 blinks. It is supposed to do.

By the way, the load applied to the drill 1 becomes relatively large and the fluctuation range becomes large as the number of machining times increases. A solid line A shown in FIG. 2 shows a torque fluctuation in a drill having a small number of working times, and a broken line B shows a torque fluctuation in a drill having a large number of working times.

As is clear from FIG. 2, as the number of drilling operations (usage time) increases, in other words, as the drill wears, the torque fluctuation width increases and its standard deviation (σa:
A drill having a small number of machining times, σb; a drill having a large number of machining times) also has a large value (σa <σb).

From this, it is possible to detect the life of the drill 1 by setting the reference torque fluctuation width in advance and comparing the reference torque fluctuation width with the torque fluctuation width during actual operation. Of course, an appropriate reference torque fluctuation range can be known by experiments.

Based on the above principle, the life detection of the drill 1 in the embodiment will be described with reference to FIGS. 3 and 4.

FIG. 3 shows a torque fluctuation when a drilling tool is used with the drill 1 which has been worn to some extent, and a large torque fluctuation is observed from T seconds after the start of processing to the end of the processing. It is considered that this phenomenon is caused by chatter vibration occurring as the worn drill 1 penetrates into the work while bending, and the hugging force increases from the work.

Therefore, in this embodiment, firstly, it is based on the torque value from T seconds after the start of machining, and secondly, the amplitude (variation width) of the torque value is replaced with the standard deviation, and the drill 1 is operated with this standard deviation. It is supposed to detect the life of the.

Specifically, as shown in FIG. 4, after T seconds have elapsed since the start of processing, the process proceeds from step S1 to step S2, the torque value is taken in, and the standard value is calculated from the n torque values immediately before the end of processing. The deviation (σ) is calculated (step S4). The standard deviation (σ) is calculated by the following formula.

Here, xi is the torque value fetched at the i-th position.

By comparing the actual standard deviation σ thus obtained with the preset standard standard deviation σ ₀ , the solid line standard deviation σ
If is large, it is determined that the drill 1 has reached the end of its life, and an alarm signal is output to the alarm lamp 6 (step S6).

The worker knows the life of the drill 1 by blinking the alarm lamp 6 and replaces the drill 1. The output of the alarm signal is released by pressing the reset button (step S7).

As described above, since the life of the drill 1 is detected by the fluctuation range of the torque, even if there is individual difference in hardness of the work, the life of the drill is accurately detected without making an erroneous determination. The Rukoto.

Further, in the embodiment, since the fluctuation range of the torque is replaced with the standard deviation to determine the life, the variation in the partial hardness within the workpiece alone, that is, the torque due to the variation in the systematic hardness. The life of the drill can be detected without being confused by the protrusion of the value (the portion indicated by C in FIG. 5).

(Effects of the Invention) As is clear from the above description, according to the present invention, in detecting the life of a drilling tool, the life is detected with excellent accuracy because it is not confused by variations in the hardness of the work. be able to.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment, FIG. 2 is an explanatory view showing a relationship between a drill life and a torque fluctuation range, FIG. 3 is an explanatory view showing characteristics of torque fluctuation, and FIG. 4 is a drill life detection. FIG. 5 is a flow chart showing an example of execution of the above, and FIG. 5 is a diagram showing the protrusion of torque due to the systematic variation in hardness existing within the workpiece alone. A: Life detection device 1: Drill 2: Load detection means 5: Microcomputer Step S5: Comparison means Step S6: Output means

Front page continuation (72) Inventor Yasuhiro Fukumoto 3-3 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) Reference JP-A-58-90445 (JP, A) JP-A-56-33256 (JP) , A)

Claims (1)

[Claims] 1. A load detection means for detecting a load applied to a drill as a drilling tool, and a load signal within a predetermined period after a predetermined time has elapsed from the start of machining of the drill upon receiving a load signal from the load detection means. Comparing means for comparing the actual amplitude based on the above with a preset reference amplitude, and output means for receiving a signal from the comparing means and outputting a tool life determination signal when the actual amplitude is larger than the reference amplitude And a tool for detecting the life of a drilling tool.