JP4432976B2 - Impact wrench air pressure adjustment method and management method - Google Patents

Description

  The present invention relates to an impact wrench air pressure adjusting method and a management method for tightening a nut using a pneumatic pressure when a wheel is fastened to a hub by tightening a nut screwed to a hub bolt, and more particularly, a wheel drop-off. The present invention relates to an impact wrench air pressure adjustment method and management method that contributes to a reduction in accidents.

  As one of the causes of accidents in which wheels (tired wheels) such as large trucks, buses, and trailers fall off, it has been pointed out that the wheels are not fastened at the time of tire replacement. The wheel is fastened by engaging the wheel bolt hole with the hub bolt and tightening the nut screwed into the hub bolt to fasten the wheel to the hub. Air pressure is used as a tool for tightening the nut. An impact wrench (see, for example, Patent Document 1) that tightens a nut is used.

Wheels are fastened with impact wrenches according to the tightening torque specified by the Japan Automobile Manufacturers Association, Japan Automobile Tire Association, etc., but nevertheless, wheel dropout accidents continue and there is a strong demand for countermeasures. It was.
Japanese Patent Laid-Open No. 5-4173

  An object of the present invention is to provide an air pressure adjustment method and a management method for an impact wrench that greatly contributes to a reduction in wheel drop accidents.

In the impact wrench air pressure adjusting method of the present invention that achieves the above object, the nut is screwed onto the hub when the nut screwed into the hub bolt projecting from the hub on the axle side of the vehicle is fastened to the hub. It is a method of adjusting the air pressure of an impact wrench that is tightened by using a hub bolt of the same kind that has deteriorated with time to the same extent as the hub bolt used when attaching the wheel to a vehicle from various hub bolts that have changed over time. Select as adjustment hub bolts, and select the same type of nuts that have deteriorated over time to the same degree as the nuts used when attaching the wheels to the vehicle from the various nuts that have changed over time . using the adjustment nut screwed to the adjustment hub bolts and the adjustment hub bolts projecting from the hub, where By the impact wrench set to the air pressure when the tightening of the adjustment nut is screwed to the adjustment hub bolts in the wheel or the same type of the wheel wheel was fastened to the adjustment hub, embedded in the adjustment hub bolts The axial force generated in the adjusting hub bolt is measured using a strain gauge, and if the measured axial force value is outside the predetermined axial force range, the air pressure of the impact wrench is adjusted. The value of the axial force to be measured is adjusted so as to fall within a predetermined range of the predetermined axial force.

  An impact wrench management method according to the present invention includes a tire wheel fastening device in which a plurality of impact wrench whose air pressures are adjusted by the impact wrench air pressure adjusting method described above is connected to one compressed air supply source via a pressure reducing valve. When the pressure of the compressed air supplied from the compressed air supply source to the impact wrench drops below a predetermined air pressure during the operation of fastening to the hub on the axle side of the vehicle, the use of the impact wrench that is notified or lowered by an alarm It is characterized by stopping.

  According to the air pressure adjustment method of the impact wrench of the present invention described above, the impact wrench can be adjusted so that the axial force falls within a predetermined appropriate range using the adjustment hub bolt and the adjustment nut. When a wheel is attached to an actual vehicle, the axial force of the hub bolt that greatly affects the fastening of the wheel can be set to an appropriate value by the adjusted impact wrench. Therefore, it is possible to prevent the occurrence of poor fastening and reduce the wheel dropping accident.

  According to the impact wrench management method of the present invention described above, the adjusted impact wrench can be operated within an appropriate compressed air pressure range. Therefore, a plurality of impact wrench are connected to one compressed air supply source for use. Even in this case, it is possible to reliably prevent the occurrence of poor fastening and reduce the wheel dropout accident.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an embodiment of an air pressure adjustment method for an impact wrench according to the present invention. 1 is an impact wrench connected to a compressed air supply source 2, 3 is an adjustment hub bolt protruding from an adjustment hub 4, and 5 is This is an adjustment nut that is screwed onto the adjustment hub bolt 3.

  The method of adjusting the air pressure of the impact wrench of the present invention is performed in advance before attaching the wheel (wheel with tire) to the hub on the axle side of the vehicle at the time of replacement or repair, and the impact wrench 1 is attached to the hub on the axle side of the vehicle. When the nut screwed to the projecting hub bolt is tightened to fasten the wheel to the hub, the nut is tightened using the pressure (air pressure) of the compressed air supplied from the compressed air supply source 2. The impact wrench 1 can adjust the tightening force (tightening torque) to a predetermined set value by switching the dial 1a. That is, by changing the dial 1a, the air pressure (flow rate of compressed air) for rotating the rotating body (hammer) built in the impact wrench 1 is adjusted, and the air pressure acting on the hammer in the impact wrench 1 is adjusted to a predetermined air pressure. It can be done.

  The hub bolt for adjustment 3 is selected from various hub bolts collected in advance and deteriorated with time, and the same condition as the hub bolt used in the vehicle (same type deteriorated with time to the same extent) is selected. . As with the adjustment hub bolt 3, the adjustment nut 5 is also selected from various nuts that have been collected in advance and deteriorated with time. The same kind) is selected.

  A strain gauge 6 for measuring the axial force of the bolt 3 is embedded in each adjustment hub bolt 3. Each strain gauge 6 is connected to the processor 8 via a lead wire 7. When axial strain occurs in the adjusting hub bolt 3, the voltage generated in the strain gauge 6 changes due to the resistance change of the strain gauge 6. The changed voltage is converted into an axial force by the processor 8, and the axial force is displayed on the display means 9 connected to the processor 8.

  FIG. 1 shows an example conforming to the ISO system, in which an adjustment nut 5 made of a single nut is used and ten adjustment hub bolts 3 are attached to the adjustment hub 4.

  The air pressure adjustment method of the impact wrench of the present invention is performed as follows using the adjustment hub bolt 3 and the adjustment nut 5 as described above. In the figure, an example of a double wheel (rear wheel) to which two wheels W are attached is shown.

  First, ten adjustment hub bolts 3 and adjustment nuts 5 are selected, and each adjustment hub bolt 3 is attached to the adjustment hub 4. Next, lubricating oil is applied to predetermined positions of each adjusting hub bolt 3 and adjusting nut 5. After the application, the wheel of the wheel or the bolt hole of the same type of wheel W is inserted into the adjusting hub bolt 3 and the two wheels W are engaged with the ten adjusting hub bolts 3. Each adjustment nut 5 is screwed into the adjustment hub bolt 3 to temporarily fix the wheel W.

Subsequently, each adjustment nut 5 is tightened by the impact wrench 1 set to a predetermined tightening force (air pressure), and the wheel W is fastened to the adjustment hub 4 . At this time, the axial force generated in each adjustment hub bolt 3 is measured. That is, the voltage changed by the strain gauge 6 due to the axial strain of each adjusting hub bolt 3 is converted into an axial force by the processor 8 and displayed on the display means 9. The display means 9 displays the axial forces of the ten adjustment hub bolts 3 respectively.

  If the measured value of each axial force is within a predetermined (proper) axial force range determined in advance, the impact wrench 1 is used in the operation of fastening the wheel to the hub on the axle side of the vehicle as it is. When there are those in which the value of the axial force of the ten adjusting hub bolts 3 is within the proper axial force and the axial force value that does not enter is determined as follows.

  Obtain the average value of the eight axial force values excluding the maximum and minimum values of the axial force of the 10 adjustment hub bolts 3, and if the average value is within the appropriate axial force range, the tightening force of the impact wrench 1 The impact wrench 1 is used in the operation of fastening the wheel to the hub on the axle side of the vehicle as it is.

  For example, the measured axial forces of the ten adjustment hub bolts 3 are 17.2 tf (approximately 168 kN), 15.7 tf (approximately 154 kN), 15.6 tf (approximately 153 kN), 15.5 tf (approximately 152 kN), 15. 3tf (approximately 150 kN), 15.2 tf (approximately 149 kN), 15.2 tf (approximately 149 kN), 15.0 tf (147 kN), 14.3 tf (approximately 140 kN), 13.3 tf (approximately 130 kN) Since it is determined whether or not the average value 15.2 tf (approximately 149 kN) of the eight axial forces excluding the value 17.2 tf (approximately 168 kN) and the minimum value 13.3 tf (approximately 130 kN) is within the appropriate axial force range. is there.

  This is because the ten adjustment hub bolts 3 and the adjustment nuts 5 used are not in the same state. If the axial force values of the 10 adjustment hub bolts 3 are extremely different, there is a possibility of eccentric installation (installation state where only one part is tightened first and no equal force is applied). Therefore, all the adjusting nuts 5 are once loosened and then tightened again.

  When the average value is outside the range of the appropriate axial force, or when the value of the axial force of the ten adjustment hub bolts 3 is outside the range of the appropriate axial force, the impact wrench 1 is tightened. The force is adjusted so that the measured axial force value falls within a predetermined range of proper axial force.

  That is, after loosening each adjustment nut 5 and turning the dial 1a of the impact wrench 1 to adjust the tightening force, the adjustment nut 5 is tightened again, and the axial force of each adjustment hub bolt 3 at that time is measured. The above process is repeated until the measured value falls within the range of the appropriate axial force according to the above-described criteria, and the impact wrench 1 is tightened so that the measured axial force value falls within the range of the appropriate axial force. The power is adjusted.

  FIG. 2 shows a main part of another embodiment of the method for adjusting the air pressure of the impact wrench of the present invention. In this embodiment, the nut used to fasten the wheel is composed of an inner nut that is screwed to the hub bolt and an outer nut that is screwed to the outside of the inner nut. The JIS method has eight hub bolts. It is to comply. Other configurations are the same as those of the embodiment of FIG.

  The inner nut 5A for adjustment and the outer nut 5B for adjustment are selected from a variety of inner nuts and outer nut nuts that have deteriorated over time, and the same conditions as the inner nuts and outer nut nuts used in the vehicle to which the wheels are attached. (Same type that has deteriorated over time to the same extent).

  In the method of this embodiment, first, each of the eight adjustment hub bolts 3, the adjustment inner nut 5 </ b> A and the adjustment outer nut 5 </ b> B is selected, and the adjustment hub bolt 3 is attached to the adjustment hub 4. Next, lubricating oil is applied to predetermined positions of each adjustment hub bolt 3, adjustment inner nut 5A, and adjustment outer nut 5B. After the application, the wheel of the wheel to be mounted on the vehicle or the bolt hole of the wheel W1 of the same type is inserted into the adjustment hub bolt 3, and the wheel W1 is engaged with the eight adjustment hub bolts 3. Each adjustment inner nut 5A is screwed onto the adjustment hub bolt 3 to temporarily fix the wheel W1.

  Subsequently, each adjustment inner nut 5 </ b> A is tightened by the impact wrench 1 set to a predetermined tightening force (pneumatic pressure), and the wheel W <b> 1 is fastened to the adjustment hub 3. At this time, the axial force generated in each adjusting hub bolt 3 is measured in the same manner as described above.

  If the measured axial forces are extremely different, there is a possibility of eccentric mounting, so that all adjustment inner nuts 5A are once loosened and then tightened again. If the measured axial force is not extremely different, another wheel W2 is attached. That is, the bolt hole of the wheel W2 is inserted into the adjustment inner nut 5A, and the wheel W2 is engaged with the adjustment hub bolt 3 via the adjustment inner nut 5A. The adjustment outer nut 5A is screwed into the adjustment inner nut 5A, and the wheel W2 is temporarily fixed.

  Subsequently, each adjustment outer nut 5 </ b> B is tightened by the impact wrench 1, and the wheel W <b> 2 is fastened to the adjustment hub 3. At this time, the axial force generated in each adjusting hub bolt 3 is measured in the same manner as described above.

  If the measured axial force is within a proper axial force range, the tightening force of the impact wrench 1 is maintained in the set state. The determination method is the same as described above. If it is outside the range of the proper axial force, the tightening force of the impact wrench 1 is adjusted so that the measured axial force value falls within the range of the proper axial force.

  That is, each adjustment outer nut 5B and the wheel W2 are removed, each adjustment inner nut 5A is loosened, and the tightening force of the impact wrench 1 is adjusted, then each adjustment inner nut 5A is tightened again, and each adjustment hub bolt 3 is fixed. Measure axial force. If the measured axial force is extremely different, tighten again and if the measured axial force is not extremely different, the wheel W2 is attached to the adjusting hub 3 with the adjusting outer nut 5B in the same manner as described above. Fasten and measure the axial force of each adjusting hub bolt 3. The above steps are repeated until the measured value falls within the proper axial force range, and the tightening force of the impact wrench 1 is adjusted so that the measured axial force value falls within the proper axial force range.

  The inventor diligently studied and experimented with the fact that a wheel dropout accident occurred despite the fact that the wheel was fastened with an impact wrench in accordance with the tightening torque specified by the Japan Automobile Manufacturers Association, the Japan Automobile Tire Association, etc. As a result of repeating the above, the following was found.

  That is, the fastening force of the wheel is greatly influenced by the axial force of the hub bolt. Assuming that the axial force of the hub bolt is F, the tightening torque of the impact wrench is T, the nominal diameter of the hub bolt is d, and the torque coefficient defined by the applied oil is K, the axial force F is F = T / (K × d) When the tightening torque T of the impact wrench is determined, the axial force F of the hub bolt is determined, and the two are correlated.

  However, in the case of a hub bolt that has deteriorated over time due to use, it has been found that the tightening torque T and the axial force F of the hub bolt do not show the correlation represented by the above formula. For example, when using a hub bolt with a nominal diameter of 2 cm that has deteriorated over time, applying engine oil (torque coefficient 0.2) and tightening the nut with a tightening torque of 56 kgf · m (approximately 550 N · m), The axial force F of the hub bolt is 14 tf (approximately 137 kN). However, when the axial force is actually measured, it is only about 10 tf (98 kN), and the correlation represented by the above formula is not established.

  Even when tightening with the same tightening torque, there are aspects where the axial force F of the hub bolt depends on the type and amount of oil applied, but to reduce the occurrence of wheel dropout accidents, the tightening torque is the same as before. It was found that it is important to manage the axial force of the hub bolts rather than managing the bolts.

  Therefore, in the present invention, the axial force is measured using the adjusting hub bolt 3 and the adjusting nut 5 as described above, and the impact wrench 1 is tightened so that the measured value falls within a predetermined appropriate range. The force (pneumatic pressure) was adjusted. Thereby, when attaching a wheel to an actual vehicle, the axial force of the hub bolt that greatly influences the fastening of the wheel can be set to an appropriate value by the impact wrench 1 with the tightening force adjusted. For this reason, the occurrence of poor fastening is suppressed, and it is possible to reduce the wheel dropout accident.

FIG. 3 shows an impact wrench management method of the present invention. When a plurality of impact wrenches 1 adjusted in tightening force as described above are used in a wheel fastening device 10 configured to be connected to one compressed air supply source 12 via a pressure reducing valve 11, a wheel dropout accident is reduced. Therefore, it manages as follows. In the figure, reference numeral 13a denotes a pressure gauge attached to each impact wrench 1. The pressure gauge 13a is viewed so that the pressure of the compressed air supplied to the impact wrench 1 can be confirmed.

  In the wheel fastening device 10, when a plurality of impact wrench 1 is used simultaneously with one compressed air supply source 12, the pressure of the compressed air supplied to the impact wrench 1 via the pressure reducing valve 11 is suitable for use of the impact wrench 1. The pressure may be lower. When the pressure of the compressed air supplied to the impact wrench 1 is reduced in this way, the tightening torque set by the impact wrench 1 cannot be generated. As a result, the tightening force (pneumatic pressure) of the folding impact wrench 1 is as described above. In spite of adjusting the hub bolt axial force to an appropriate value, the hub bolt axial force becomes insufficient due to a decrease in the tightening torque, and the wheel dropout accident cannot be reduced.

  Therefore, when the pressure of the compressed air supplied from the compressed air supply source 12 to the impact wrench 1 falls below a predetermined air pressure suitable for use during the operation of fastening the wheel 13 to the hub on the axle side of the vehicle 14. The alarm means 15 installed in each impact wrench 1 issues an alarm such as a sound to inform the operator that the pressure of the compressed air supplied to the impact wrench 1 has dropped below a predetermined air pressure suitable for use.

  Since the operator can know the pressure drop of the compressed air by the alarm, the use of the lowered impact wrench can be stopped immediately. Therefore, the impact wrench 1 with the adjusted tightening force can always be operated within the range of the appropriate compressed air pressure, and even when a plurality of impact wrench 1 are operated by one compressed air supply source 12, It is possible to reliably prevent the occurrence of poor fastening, and to effectively reduce the wheel dropout accident.

  Although it is preferable to install the alarm means 15 in this way, instead, the operator may stop using the impact wrench with the compressed air pressure decreased by looking at the pressure gauge 13.

  Since wheel dropout accidents occur more frequently on the rear wheel consisting of multiple wheels than on the front wheel consisting of single wheels, the above embodiment has shown an example of multiple wheels, but the front wheels consisting of single wheels are fastened to the hub on the axle side of the vehicle. It goes without saying that the method of the present invention can also be suitably used in this case.

It is explanatory drawing which shows one Embodiment of the air pressure adjustment method of the impact wrench of this invention. It is explanatory drawing which shows the principal part of other embodiment of the air pressure adjustment method of the impact wrench of this invention. It is explanatory drawing which shows one Embodiment of the management method of the impact wrench of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Impact wrench 3 Adjustment hub bolt 4 Adjustment hub 5 Adjustment nut 5A Adjustment inner nut 5B Adjustment outer nut 13 Wheel 14 Vehicle W Wheel

Claims (2)

A method of adjusting an air pressure of an impact wrench that tightens a nut using air pressure when a wheel is fastened to the hub by tightening a nut screwed to a hub bolt protruding from a hub on the axle side of a vehicle. The same kind of hub bolt that has deteriorated with time to the same extent as the hub bolt used when attaching the wheel to the vehicle is selected as the adjusting hub bolt from the various hub bolts that have been collected in advance, and the various hub bolts that have been collected in advance screw from the nut, to the wheel to select the same type of nut degraded over time to the same extent as the nut to be used when mounting on the vehicle as the adjustment nut, projecting from the adjustment hub the adjustment hub bolts and the adjustment hub bolts using the adjusting nut case, Habubo for the adjustment by the impact wrench that is set to a predetermined air pressure Tighten the adjustment nut is screwed to the capital of the wheel or the same type of the wheel of the wheel when fastened to the adjustment hub, the adjustment hub bolt with a strain gauge is embedded in the adjustment hub bolts If the measured axial force value is outside the predetermined range of the predetermined axial force, the air pressure of the impact wrench is adjusted, and the measured axial force value is A method of adjusting the air pressure of an impact wrench so as to be within a predetermined range of predetermined axial force.   In a wheel fastening device in which a plurality of impact wrenches whose air pressures are adjusted by the method of claim 1 are connected to one compressed air supply source via a pressure reducing valve, during the operation of fastening the wheels to a hub on the axle side of the vehicle, A method for managing an impact wrench, in which, when the pressure of compressed air supplied from a compressed air supply source to an impact wrench drops below a predetermined air pressure, the use of the impact wrench notified by an alarm or the lowered impact wrench is stopped.