JP2012245604A - Breakage inspection method and device for small-diameter tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely detect whether or not such a small-diameter tool as that smaller than 0.5 mm in diameter is broken by a non-contacting inspection method that hardly causes the breakage of the tool even in an environment in which mist such as that of cutting oil is spattered.SOLUTION: An injection nozzle 1 and a receiving nozzle 2 are opposed to each other. A certain amount of air is jetted in vain from the injection nozzle 1 before installing a tool 10 in an inspection section A. Then, a flow volume threshold is set based on an air volume Q1 taken into the receiving nozzle 2 at this time. The flow volume threshold is set desirably at each inspection. Thereafter, the tool 10 is inserted into the inspection section A, and in this state, a certain volume of air is jetted again from the injection nozzle 1. Then, the air volume Q2 jetted at this time is compared with the flow volume threshold, thereby deciding whether or not an inspection target tool is broken.

Description

  The present invention relates to a breakage inspection method and a breakage inspection apparatus that enable a rod-shaped small diameter tool such as a small diameter drill to be accurately inspected for the presence or absence of breakage without damaging the tool.

  For example, a small-diameter drill called a micro drill or a miniature drill is easily broken during use, and the breakage causes a processing defect of the product. For this reason, inspecting the presence or absence of breakage in the state set in the processing machine is performed.

  As a breakage inspection apparatus for a rod-shaped tool typified by the small-diameter drill, those shown in Patent Documents 1 and 2 below are known.

  The inspection apparatus employed in the tool mounting apparatus of Patent Document 1 uses a photoelectric sensor, and changes in the amount of light received by the light receiving unit as to whether or not the light path between the light projecting and light receiving units is blocked by the tool. Check to see if the tool is broken.

  In addition, the blade breakage detection apparatus of Patent Document 2 uses a touch sensor, and detects and detects a change in the pressure in the flow path that causes whether or not the tool is in contact with the sensor.

JP-A-62-94210 JP 2000-33535 A

  In recent years, the diameter of tools has been reduced, and ultrafine drills having a diameter of less than 0.5 mm have been put into practical use. When the presence or absence of breakage of the ultrafine drill or the like is inspected using a device using a touch sensor, the tool may be damaged by the pressure at the time of measurement.

  In addition, inspection devices using photoelectric sensors do not have to worry about damaging the tool, but cutting oil and coolant are often used for drilling, etc., and the inspection device is operated to shorten the inspection time. If incorporated in the machine, the inspection will be carried out in an environment in which cutting oil or coolant liquid scatters unavoidably, making it difficult to guarantee the inspection accuracy.

  The sensitivity of the photoelectric sensor decreases when the cutting oil or the like adheres, thereby reducing the accuracy of inspection. The breakage referred to in the present invention includes a slight defect at the tip, and such a breakage is particularly likely to be mistakenly overlooked.

  An object of the present invention is to make it possible to accurately detect the presence or absence of breakage of a small-diameter tool by non-contact inspection without fear of damaging the tool even in an environment where mist such as cutting oil scatters.

In order to solve the above-described problems, in the present invention, the injection nozzle for injecting air and the receiving nozzle for taking in the injected air are opposed to each other with the inspection portion interposed therebetween, and before the tool is introduced into the inspection portion, A fixed amount of air is injected from the injection nozzle in an idle state, and at this time, a flow rate threshold is set based on the amount of air Q1 taken into the receiving nozzle,
Thereafter, a tool is inserted into the inspection section, and in this state, a fixed amount of air is again injected from the injection nozzle, and the air amount Q2 taken into the receiving nozzle at this time is compared with the flow rate threshold value to be inspected. The present invention provides a breakage inspection method for a small-diameter tool that determines whether or not a tool is broken and sets the flow rate threshold value by air blow in each inspection or every several inspections.

  The flow rate threshold value can be obtained by multiplying an air amount Q1 (this is a variable) measured by air blanking by a certain coefficient. The coefficient used for the calculation of the flow rate threshold is not less than a value obtained by adding a tolerance to a numerical value obtained by the expression {1- (N / 100)}, where N% is a ratio at which the injected air is blocked by a normal tool. Set as follows. The tolerance mentioned here is, for example, about + 10% to −10% of N. In addition, the flow rate threshold value may be a value always smaller by a certain amount than the air amount Q1.

  In such an inspection method, it is preferable to set the flow rate threshold value by air blanking in every inspection.

The present invention also provides a breakage inspection apparatus for executing the above method. The breakage inspection device includes an injection nozzle that injects air toward the inspection unit, a receiving nozzle that takes in the injected air at a facing position, an air source that supplies air to the injection nozzle, and a flow rate control that controls the amount of air supplied A valve, a flow sensor for measuring the amount of air taken into the receiving nozzle, a control device for controlling the operation of the device, and a calculation / determination device are provided.

  Then, air injection is performed in the state where there is no tool in the inspection unit, the air amount (flow rate) Q1 is measured by the flow rate sensor, and the arithmetic / determination device multiplies the measured air amount Q1 by a certain coefficient. A flow rate threshold is set, and the presence or absence of tool breakage is determined by comparing the flow rate threshold with the air amount Q2 measured by the flow rate sensor when air injection is performed in a state where the tool is introduced into the inspection unit. The setting of the flow rate threshold value by the air blow is performed in every inspection or every several inspections. In addition, when the measured air amount Q1 is compared with the previous air amount and it is determined that the difference is larger than a predetermined value, it is considered that a large change has occurred in the measurement environment. You may make it check an apparatus.

  This breakage inspection apparatus includes a receiving nozzle having an end surface on the air introduction side formed as a convex curved surface, and a mist filter that collects mist mixed in the jet air between the receiving nozzle and the flow rate sensor. What installed this is preferable.

The air amounts Q1 and Q2 can be replaced with air pressures P1 and P2. That is, an injection nozzle that injects air and a pressure detection unit that detects the pressure of the injected air are arranged opposite to each other with an inspection unit interposed therebetween, and before introducing a tool to the inspection unit, the injection nozzle is fixed from the injection nozzle. Pressure air is blown and ejected, and at this time, a pressure threshold is set based on the air pressure P1 detected by the pressure detector,
Thereafter, a tool is inserted into the inspection unit, and in this state, air of a constant pressure is again ejected from the injection nozzle, and the air pressure P2 detected by the pressure detection unit at this time is compared with the pressure threshold value. Even in the method for determining whether or not the inspection target tool is broken, the presence or absence of breakage of the small-diameter tool can be accurately detected without bringing the tool into contact with the pressure sensor. The present invention also provides such an inspection method.

  In this inspection method in which the flow rate is replaced with pressure, the setting of the pressure threshold value by air blanking is performed every inspection or every several inspections. The pressure threshold value in this case can also be obtained by multiplying the air pressure P1 measured by idle driving by a certain coefficient.

  The inspection method and the inspection apparatus of the present invention are used because a predetermined amount (or constant pressure) of air is blown prior to inspection and a threshold is set based on the air amount Q1 (or air pressure P1) at that time. Measurement accuracy does not deteriorate due to environmental factors and time-dependent factors.

  For example, even if the flow resistance increases due to mist adhesion etc. and the amount of air flowing to the flow sensor decreases every time the inspection is performed, or the sensitivity of the pressure sensor decreases due to the increase in deposits over time, A factor (which is referred to as an error factor here) that corrects the measurement result by correcting the threshold value immediately before the inspection is eliminated, thereby accurately determining whether or not the tool is broken.

  In particular, inspection devices with a mist filter installed between the receiving nozzle and the flow sensor clog the filter due to the collection of mist and foreign matter, and the flow resistance gradually increases, but this causes a decrease in the measured flow rate. However, measurement accuracy is maintained, leading to early detection of tool breakage.

  By identifying and removing the cause of breakage at an early stage, it is possible to prevent the tool from being lost in a chain due to the same cause.

  The threshold values of the flow rate and pressure can be obtained by multiplying the air amount Q1 and air pressure P1 measured by idle driving by a predetermined coefficient. As a coefficient used at this time, a numerical value that is 1 or less and larger than a value obtained by adding a tolerance to a value obtained by the above equation {1- (N / 100)} is selected.

  If the coefficient is close to a value obtained by adding a tolerance to the numerical value obtained by the expression {1- (N / 100)}, the air amount Q2 measured even when a part of the tool tip is slightly missing is a threshold value. Therefore, it is possible to detect without missing a tool. Moreover, it is possible to prevent a normal tool from being mistaken for a broken product by setting a value obtained by adding a tolerance to a numerical value obtained by the expression {1- (N / 100)} as a lower limit of the threshold value.

  Although the threshold setting is not limited to every time, the air amount Q1 (air pressure P1) measured in the current inspection is compared with the air amount Q1 (air pressure P1) measured in the previous inspection. If it does not fluctuate greatly, the increase in the error factor between the previous test and the current test may be considered to be small. In such a case, the threshold may be changed every several times. This still achieves the object of the invention.

  In the case where the threshold value is set every time, the determination based on the optimum threshold value is always performed, so that an increase in machining defects due to breakage detection delay can be suppressed.

Further, in the breakage inspection apparatus according to the present invention, when the end surface on the air introduction side of the receiving nozzle is formed with a convex curved surface, it is difficult for mist and foreign matter to enter the air introduction port of the receiving nozzle, and in the vicinity of the air introduction port. The mist and foreign matter adhering to the air can be well blown, and an increase in maintenance labor can be suppressed.

System configuration diagram of breakage inspection apparatus of the present invention The figure which shows the detailed structure of an example of the principal part of an inspection apparatus Principle of breakage detection The figure which shows an example of the inspection object tool Schematic diagram showing the relationship between the air amount Q1, the threshold value, and the air amount Q2 at the time of inspection of broken tools and non-breaking tools

  Embodiments of a breakage inspection method and a breakage inspection apparatus for a small diameter tool according to the present invention will be described below with reference to FIGS. 1 to 5 of the accompanying drawings.

  FIG. 1 shows an outline of the overall configuration of the breakage inspection apparatus. This breakage inspection apparatus includes an injection nozzle 1 and a receiving nozzle 2 that are opposed to each other with an inspection unit A interposed therebetween, an air source 3, and a flow rate control valve (electromagnetic valve) 4 that controls the amount of supplied air. Have.

  Further, a flow sensor 5 for measuring the amount of air taken in by the receiving nozzle 2, a mist filter 6 installed between the receiving nozzle 2 and the flow sensor 5, and a monitor 7 for displaying a measurement value by the flow sensor 5; The control device 8 controls the operation of the device, and is configured by combining the above elements.

  The flow rate control valve 4 receives an operation command from the control device 8 and opens for a certain time, and flows a certain amount of air supplied from the air source 3 toward the injection nozzle 1.

  The air is injected by the injection nozzle 1 toward the receiving nozzle 2, and the air is taken into the receiving nozzle 2. A tool 10 to be inspected (a tip side that requires inspection of the tool) is inserted into an inspection portion A provided between the injection nozzle 1 and the receiving nozzle 2. The air flow path between the injection nozzle 1 and the receiving nozzle 2 is blocked by the tool, whereby the amount of air taken into the receiving nozzle 2 varies, and the presence or absence of breakage of the tool is determined based on the variation amount.

  Before introducing the tool 10 to the inspection section A, a certain amount of air is ejected from the ejection nozzle 1 in an idle state, and the amount of air taken into the receiving nozzle 2 at that time is measured by the flow sensor 5. Then, the air amount Q1 (see FIG. 5) is input as basic data to the calculation / determination unit 9 incorporated in the monitor 7.

  The calculation / determination unit 9 calculates a flow rate threshold value T (see FIG. 5) that serves as a determination criterion based on the air amount Q1. The flow rate threshold value is equal to or greater than a value obtained by adding a tolerance to a constant coefficient in the air amount Q1 measured by idle driving, specifically, a numerical value obtained by the expression {1- (N / 100)}. It is obtained by multiplying the following coefficient (for example, 0.9).

  After obtaining the flow rate threshold T, the tool 10 to be inspected is inserted into the inspection part A as shown in FIG. FIG. 3A shows a state in which a normal tool 10 that is not bent is introduced into the inspection section A, and the flow path between the injection nozzle 1 and the receiving nozzle 2 is blocked by the tool 10, and FIG. FIG. 4 shows a state in which the tool 10 with the tip 10a broken is introduced into the inspection part A as shown in FIG. 4 (a state where the tool 10 does not block the flow path).

  Then, in this state where the tool 10 is introduced to a predetermined position, a certain amount of air (same amount as when idling) is again ejected from the ejection nozzle 1, and the air amount Q2 taken into the receiving nozzle 2 at this time is monitored 7 Is compared with a threshold value T set in advance in the calculation / determination unit.

  If the air amount Q2 exceeds the threshold value T (see the center data in FIG. 5), the calculation / determination unit 9 determines that the tool is broken, and if the air amount Q2 is below the threshold value T ( Data on the right end of FIG. 5) The tool is determined not to be broken, and the result is displayed on the monitor 7.

  The example inspection apparatus is configured to perform the setting of the flow rate threshold value T by air blown every time, and by resetting the flow rate threshold value in each inspection, the time between the previous inspection and the current inspection is set. Condition fluctuations are corrected, and each inspection is performed under appropriate conditions, and an accurate inspection is performed.

  If the difference between the air amount Q1 in the previous inspection and the current inspection is small, the current inspection may be performed using the threshold value in the previous inspection as it is. Even if the air amount Q1 when the air is blown in each inspection is decreased by a predetermined value or more with respect to the air amount Q1 when the previous threshold value was changed, the threshold value is also reset to correct the temporal variation of the inspection conditions. can do.

  FIG. 2 shows an example of a preferable structure of the main part of the inspection apparatus of the present invention. As shown in the drawing, the receiving nozzle 2 has an air introduction side end face 2a formed in a convex curved surface, and an air introduction port 2b is opened in the convex curved end face 2a.

  According to this structure, it is difficult for mist and foreign matter to enter the air introduction port 2b, and the mist and foreign matter adhering to the vicinity of the air introduction port 2b can be well blown. For this reason, adhesion, residual, and uptake of mist and foreign matters are reduced, and it is possible to expect effects such as reduction in maintenance labor and extension of replacement time of the mist filter.

  The dimensions of the inspection apparatus of FIG. 2 are as follows: the inner diameter d of the injection nozzle 1 and the receiving nozzle 2 is 0.5 mm, the arc radius R of the air introduction side end surface 2a of the receiving nozzle 2 is 20 mm, and the injection nozzle 1 and the receiving nozzle. 2 distance L = 5 mm, inner diameter d1 of the air pipe connected to the injection nozzle 1 and the receiving nozzle 2 = φ1.5 mm, mist filter filtration capacity 0.3 μm, measurement capacity of the flow sensor 5: 0 to 0.5 liters / Min.

  The air jetted from the jet nozzle 1 of this apparatus moves forward with a spread angle of about 10 ° and collides with the end face 2a of the receiving nozzle 2 on the air introduction side.

  The apparatus shown in FIGS. 1 and 2 determines the presence or absence of a tool deficiency by checking the fluctuation state of the air amount. Instead of checking the fluctuation state of the air amount, the method of checking the fluctuation state of the air pressure can be used. The presence or absence of defects can be inspected without causing the problems seen in conventional methods.

  1 is replaced with a pressure control valve, the flow sensor 5 is replaced with a pressure detection unit, the receiving nozzle 2 is omitted, and a pressure detection unit (pressure sensor) is disposed at that position. A constant air pressure to be injected is caused to collide with a pressure detection unit arranged oppositely. Then, the air pressure when air is blown and ejected from the injection nozzle 1 is measured by the pressure detection unit, and a pressure threshold is set by multiplying the measured air pressure P1 by a certain coefficient.

  Thereafter, a tool is inserted into the inspection part A, air of a constant pressure is again ejected from the injection nozzle 1, and the air pressure P2 detected by the pressure detection part at this time is compared with the pressure threshold value. This method also corrects the threshold value set before the error factor is taken in by setting a threshold value for every inspection or every several inspections. It is possible to accurately detect without contacting the sensor.

  The inspection device having the specifications shown in FIG. 2 was assembled to the workpiece transfer device of the processing machine. Then, the apparatus was adjusted so that the flow rate detected by the flow rate sensor 5 when the tool 10 was not introduced into the inspection unit A was 0.4 liter / min.

Further, a tool (drill) 10 having a diameter of 0.1 mm was introduced into the inspection section A of this inspection apparatus, and air was injected from the injection nozzle 1 under the same conditions as when no tool was present. At that time, the flow rate measured by the flow rate sensor 5 was 0.3 liter / min.
Further, a measurement flow rate of 0.4 liter / min without a tool was used as basic data, and this was multiplied by 0.1 as a coefficient to set a threshold value in the initial inspection. The above 0.1 is also used as a coefficient to be multiplied by the flow rate Q1 measured by idle driving in setting the threshold value in the second and subsequent inspections.

  Using this inspection device, a tool having a diameter of 0.1 mm was inspected for breakage. As a result, it was possible to stably detect a tool with a tip lacking 0.4 mm in length as a breakage.

  In order to evaluate the inspection method and the inspection apparatus according to the present invention, the number of tool breaks during one month was compared with the case of visual inspection. In the visual inspection, the operator periodically checks the processing machine and checks the breakage status of the tool using a tool microscope. The inspection is 100% inspection, but it is difficult to detect defects of only about 0.4 to 0.5mm in a small diameter tool by visual inspection. Sometimes occurred.

  On the other hand, in the inspection method of the present invention, breakage was detected at an early stage, and tool breakage could be suppressed to 10% or less of the number generated by visual inspection, and to a few when it was small.

  For this reason, the processing machine can be operated unattended, which has greatly improved productivity.

DESCRIPTION OF SYMBOLS 1 Injection nozzle 2 Receiving nozzle 2a Air introduction side end surface 2b Air introduction port 3 Air source 4 Flow rate control valve 5 Flow rate sensor 6 Mist filter 7 Monitor 8 Control device 9 Calculation / determination part 10 Tool 10a Tip A Inspection part Q1 Measured air amount Q2 Measured air amount P1 during tool inspection Measured air pressure P2 when blanking Measured air pressure T during tool inspection Threshold

Claims (6)

Before injecting the tool into the inspection section (A), the injection nozzle (1) for injecting air and the receiving nozzle (2) for taking in the injected air are opposed to each other with the inspection section (A) interposed therebetween. A fixed amount of air is ejected from the nozzle (1) in an idle state, and a flow rate threshold is set based on the amount of air Q1 taken into the receiving nozzle (2) at this time,
Thereafter, a tool is inserted into the inspection section (A), and in this state, a fixed amount of air is again injected from the injection nozzle (1), and at this time, the amount of air Q2 taken into the receiving nozzle (2) is set. Judge the presence or absence of breakage of the inspection target tool compared to the flow rate threshold,
A breakage inspection method for small-diameter tools, in which the flow rate threshold is set every time or every several inspections.   The breakage inspection method for a small-diameter tool according to claim 1, wherein the flow rate threshold value is obtained by multiplying the air amount Q1 by a constant coefficient. An injection nozzle (1) that injects air toward the inspection section (A), a receiving nozzle (2) that takes in the injected air at an opposing position, and an air source (3) that supplies air to the injection nozzle (1) And a flow rate control valve (4) for controlling the amount of supplied air, a flow rate sensor (5) for measuring the amount of air taken into the receiving nozzle (2), a control device (8) for controlling the operation of the device, Computation / judgment device (9)
Air injection is performed in the state where there is no tool in the inspection section (A), the air amount Q1 is measured by the flow rate sensor (5), and the arithmetic / judgment device (9) is fixed to the measured air amount Q1. A flow rate threshold value is set by multiplying a coefficient, and the air amount measured by the flow rate sensor (5) when the air flow is injected with the flow rate threshold value and the tool (10) introduced into the inspection unit (A). Q2 is compared to determine the presence or absence of tool breakage,
A breakage inspection device for a small diameter tool configured such that the setting of a flow rate threshold value by air blow is performed in every inspection or every several inspections.   The breakage inspection device for a small-diameter tool according to claim 3, wherein an end surface (2a) on the air introduction side of the receiving nozzle (2) is formed as a convex curved surface.   The breakage of a small diameter tool according to claim 3 or 4, wherein a mist filter (6) for collecting mist mixed in the jet air is installed between the receiving nozzle (2) and the flow rate sensor (5). Inspection device. Before injecting a tool into the inspection section (A), an injection nozzle (1) for injecting air and a pressure detection section for detecting the pressure of the injected air are arranged opposite to each other with the inspection section (A) in between. , Injecting a constant pressure of air from the injection nozzle (1) in an idle state, setting a pressure threshold based on the air pressure P1 detected by the pressure detection unit at this time,
Thereafter, a tool is inserted into the inspection part (A), and in this state, air of a constant pressure is again injected from the injection nozzle (1). At this time, the air pressure P2 detected by the pressure detection part is Judge the presence or absence of breakage of the tool to be inspected compared to the pressure threshold,
A breakage inspection method for a small-diameter tool in which the pressure threshold is set every time or every several inspections by air blow.

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