JPH0155948B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a power wrench used to strongly tighten or disassemble objects to be fastened, such as bolts and nuts, by increasing the input torque from an operating handle or the like. Regarding.

The present invention also relates to the above-mentioned power wrench to which a torque measurement function is added.

(Prior art and problems to be solved by the invention) Conventionally, when fastening objects such as bolts and nuts with a large tightening torque, and moreover, with a predetermined tightening torque, a torque wrench has been combined with a power wrench. Ta. And at this time,
Input torque value Ti of the torque wrench, tightening torque value To of the fastened object, and power increase ratio a of the power wrench
The following relationship holds true between .

To=aTi...(1) Moreover, the power increase ratio a can be expressed by the following equation, which is the theoretical power increase ratio ao obtained by theoretical calculation multiplied by the mechanical efficiency η of the speed reduction mechanism of the power wrench, etc.

a=ηao...(2) By the way, conventionally it was assumed that a=ao, and To=
The tightening torque value To was calculated as aoTi, but even if η is considerably smaller than 1 due to wear of the gears in the reduction mechanism, deterioration of the lubrication condition, etc., Ti=T ₀ /a When the value reached ₀ , it was assumed that the object to be fastened was tightened with a predetermined tightening torque value. However, the actual tightening torque value at this time is significantly insufficient compared to the value obtained by calculation (ηaoTi<<aoTi), and there is a problem that accurate tightening work cannot be performed.

In addition, in the conventional method, the input torque value of the torque wrench
There was also the hassle of having to calculate Ti.

(Means for Solving the Problems) In order to solve the problems of the above-mentioned conventional example and to provide a power wrench equipped with a low-cost and highly accurate torque measuring device, the present invention provides a power wrench with rotational force as exemplified in the illustrated embodiment. an input shaft 1 that receives the fastened object a; an output shaft 3 that rotates the fastened object a; a casing 6 that supports the input shaft 1 and the output shaft 3; In the power wrench, the power wrench is equipped with a deceleration mechanism 8 that outputs an output to the output shaft 3, and a reaction force receiver 9 that stops the rotation of the casing 6 by locking it to a fixed object b outside the power wrench. 9 integrally provided on the casing 6, and a reaction force receiving arm 1 rotatably arranged relative to the casing 6.
A load measuring unit 12 is disposed between the casing arm 10 and the reaction force receiving arm 11 to measure the compressive force or tensile force acting between them. A torque display device 13 that converts measured values into torque values and displays them is connected to a load measuring unit 12.
It is characterized by being integrally provided on the top.

(Embodiment) The illustrated embodiment has a rectangular fitting hole 15 on the top surface of the input shaft 1 that fits into the square drive 16 of the operating handle 14. Input torque) can be taken into the input shaft 1, and a socket 17 can be removably attached to the output shaft 3, and fastened objects such as bolts and nuts can be
It is made to rotate so that it can be tightened or disassembled.

A sun gear 2 is attached to the input shaft 1, and a sun gear 2 is attached to the output shaft 3.
are each provided with a carrier 5, and the carrier 5 supports four planetary gears 4, 4, . . . .
The planetary gear 4 meshes with the outer periphery of the sun gear 2 and also meshes with an internal gear 7 formed on the inner surface of the casing 6, and is guided by the internal gear 7 to revolve around the sun gear 2. The input shaft 1 and the output shaft 3
are both supported by the casing 6.

The casing 6 is integrally provided with a casing arm 10 that projects in the radial direction, and a reaction force receiving arm 11 that projects in the radial direction is rotatably supported around the output shaft 3. The casing arm 10 and the reaction force receiving arm 11 are disposed in a plane in which they abut against each other, and a load measuring unit 12 is disposed between these abutting surfaces to measure the compressive force acting between them. Specifically, a spring type compressive force measuring device is attached to the casing arm 10.

The compressive force measured by the load measuring unit 12 causes the pointer 18 of the dial gauge type torque display device 13 to rotate by a predetermined amount. The scale 19 of the torque display device 13 displays a numerical value obtained by converting the compressive force into a tightening torque value using a predetermined calculation formula (see formula (3)). Incidentally, the torque display device 13 is integrally mounted on the load measuring unit 12.

Next, the operation of the power wrench of the present invention will be explained.
For example, to explain the case of tightening the bolt a clockwise with a predetermined tightening torque, first, in order to prevent the rotation of the casing 6, the reaction force receiving arm 11 is attached to a fixed object b (FIG. 2) outside the power wrench. After the casing 6 is locked, the operating handle 14 is rotated clockwise (if a ratchet type operating handle is used, it is set so that it can be freely rotated in the counterclockwise direction). As a result, the casing arm 10 tries to rotate counterclockwise, but this rotation is caused by the fixed object b.
The reaction force receiving arm 11 is restrained by the reaction force receiving arm 11. Therefore, the input torque of the operating handle 14 is amplified by the planetary gear mechanism (reduction mechanism) 8, transmitted to the socket 17 attached to the output shaft 3, and rotated clockwise to tighten the bolt a.

At this time, the following equation holds between the tightening torque To for tightening the bolt a and the reaction torque Tc of the casing arm 10.

To=ηc(ao−1)Tc...(3) Here, ηc is the casing arm 10 and output shaft 3
The mechanical efficiency between and ao is a constant at the theoretical amplification ratio.

The reaction torque Tc expressed by the equation (3) acts on the load measuring unit 12 as a compressive force, which is converted and displayed on the torque display measuring station 13 as a torque value indicating the tightening torque.

The friction portion in the torque transmission path between the casing arm 10 and the output shaft 3 is
Since the frictional portion is small compared to the frictional part in the torque transmission path between the output shaft 3 and the output shaft 3, the above ηc is
(2)) can be brought closer to 1, and
Fluctuations in ηc after long-term use can also be reduced. Therefore, the torque value displayed on the torque display device 13 can be close to the actual tightening torque value, and this can be made highly reliable. If the displayed torque value of the torque display device 13 is determined in advance, reliability can be further improved.), Accurate tightening work can be expected.

The present invention can be configured in various ways other than those shown in the above embodiments. For example, the input shaft 1 may have a structure in which a bar handle is directly attached to the input shaft 1, or the input shaft 1 may be configured to accept input torque from an electric drive device, an air drive device, a hydraulic drive device, or the like. The above embodiment also includes a sun gear 2, planet gears 4, 4..., a carrier 5, and an internal gear 7.
Although the speed reduction mechanism 8 is configured with a planetary gear mechanism, it is not limited thereto. Further, the aspect of the reaction force receiving section 9 formed by combining the casing arm 10 and the reaction force receiving arm 11 is not limited to that shown in the above embodiment. Further, in the above embodiment, the load measuring unit 12 measures the compressive force acting between the casing arm 10 and the reaction force receiving arm 11, but the load measuring unit 12 is also used to measure the tensile force between the two. 12 may be configured. Also, as the load measurement unit 12, a strain gauge type measurement device (load cell) which is integrated with a battery and a control circuit and is integrated with the torque display device 13,
It is also possible to use a hydraulic measuring device that has a built-in hydraulic circuit and is integrated with the torque display device 13 to measure the compressive force or the tensile force. The torque display device 13 shown in the above embodiment can be of a type other than the dial gauge type. Furthermore, a socket 1 is connected to the output shaft 3.
7 may be integrally formed, or a fastened object a may be integrally formed on the output shaft 3.
It is also possible to attach a fitting member other than the socket that fits into the socket.

(Actions and Effects of the Invention) Since the present invention has the above configuration, it can achieve the following actions and effects.

By using the power wrench with a torque measuring device of the present invention, as explained in detail in the functional explanation of the embodiment, more accurate tightening torque can be obtained compared to a combination of a conventional torque wrench and a power wrench. Accurate tightening work can be performed.

In the present invention, the reaction force receiving section is constructed by combining a casing arm and a reaction force receiving arm, and torque is measured by measuring the compressive force or tensile force acting between the two using a load measuring unit. Since the load measuring unit only needs to measure a simple force such as compressive force or tensile force, a commercially available unitized spring type measuring device or load cell can be used. Furthermore, a torque display device that converts the measured value of the load measuring unit into a torque value and displays it is provided integrally on the load measuring unit, so that the measured torque can be immediately determined. In this way, the present invention is configured so that it is sufficient to measure a simple force such as compressive force or tensile force, so the load measuring unit can have a simple and low-strength structure, and the torque display device can be integrated into it. As a result, there is no need for a separate electrical measurement/display device or lead wires for connection to it, making it possible to provide a power wrench that is convenient for torque measurement at low cost. . In addition, the input to be measured given to the load measuring unit can be compressive force or tensile force placed in an appropriate range by both arms (see equation (3)), and from this point of view, it is possible to use a low-cost load measuring unit. It has become advantageous to accurately measure torque with a measuring unit.

[Brief explanation of drawings]

FIG. 1 is a partially longitudinal front view of an embodiment of the present invention, and FIG. 2 is a partially transverse plan view thereof. 1...Input shaft, 2...Sun gear, 3...Output shaft, 4...Planetary gear, 5...Carrier, 6...Casing, 7...Internal gear, 8...Planetary gear mechanism (reduction mechanism) , 9...Reaction force receiver, 10...Casing arm, 11...Reaction force receiver arm, 12...Load measurement unit, 13...Torque display device, a
...Object to be fastened, b...Fixed object.

Claims (1)

[Claims] 1. An input shaft that receives rotational force, an output shaft that rotates the fastened object, a casing that supports the input shaft and the output shaft, and decelerates the input of the input shaft via the casing and outputs it to the output shaft. A power wrench that is equipped with a speed reduction mechanism and a reaction force receiver that stops rotation of the casing by locking it to a fixed object outside the power wrench, the casing arm having the reaction force receiver integrally provided with the casing. and,
It is constructed by combining a reaction force receiving arm rotatably arranged with respect to the casing, and a load measuring unit is arranged between the casing arm and the reaction force receiving arm to measure the compressive force or tensile force acting between them. 1. A power wrench with a torque measuring device, characterized in that a torque display device is integrally provided on the load measuring unit, and a torque display device that converts the measured value of the load measuring unit into a torque value and displays the torque value.