DE2629484A1 - DEVICE FOR TIGHTENING SCREW-LIKE PARTS ACCORDING TO A PRESET TORQUE - Google Patents

Description

PATENT ADVOCATE DIPL.-PHYS. LUTZ H. PRÜFERD-8000 MUNICH 9O

MST Macchine Speciali Torino SpA Grugliasco (Turin), Italy

Device for tightening screw-like parts according to a specified torque

The invention relates to a device for tightening screw-like Parts according to a specified torque, at which the tightening by the action of a drive, e.g. a compressed air motor he follows.

Such devices are generally known and mostly comprise a drive _t an. the shaft of which sits the wrench, which is attached to the head of the screw or screw to be tightened

PATEtMTANWALTY DIPU-PHVS. LUTZ H.PPÜFER · D-8OOO MÜKCKiK 9O ■ WlLLROiDERSTR. 8 · TEL. (0S9) S40640

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benbolzens adapts; the drive is installed in its bearings in such a way that that it revolves around the axis of its own shaft, whereby its Counteract rotation elastic means, which represent a torsion dynamo met it. The drive is in the moment switched off, where the reaction moiaent on the bearing has an elastic: triggers a braked rotation of a preselected angular width, which corresponds to a certain tightening torque. Often there is a feeling device provided for the extent of this rotation, which switches off the drive motor when a limit value is exceeded.

Such known devices have not a few disadvantages. Above all, their structure is complicated and space-consuming because of the rotatable installation of the drive motor. The space requirement is a critical condition for devices of this type.

Namely, such devices are inter alia. The requirement made - that it is possible to have a large number of the same devices on one plate to enable the simultaneous tightening of several threaded elements that fasten a mechanical part. A typical example of this is the assembly of the head part of Internal combustion engines, with the small distance between the individual screw bolts narrowing the dimensions of the tightening devices Limits.

The purpose of the invention is to create a dynamometric Screw tightening device with a smaller space requirement, which is in the It is capable of tightening torques that can be adjusted within narrow tolerances to transfer which tolerances meet the requirements Assembly of devices are also sufficient, in which critical r te apply.

The inventive device for screw tightening after a;

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preselected torque includes a motor that drives a non-rotatable pinion, which with planetary gears of an epicyclic gear combs, which are carried by a circulating bridge, which with a Member is firmly connected, which is intended to be in the to be screwed threaded part to be fitted, the planet gears also meshing with a rotating ring gear, on which Member brake means act with a preselected torque, while also sensing members for rotating the ring gear are provided that stop the supply of the drive motor at the moment when the ring gear against its rotation called braking means begins.

Purposes and advantages of the invention .such as the 'essential design features of the proposed device are evident from the following description of an exemplary embodiment, which is shown in the accompanying drawing in which

1 shows a view of a dynamometric tightening device according to the invention with a partial longitudinal section along the line I-j of Fig. 2, and

FIG. 2 shows a cross section along line II-II of FIG.

The device shown comprises a designated as a whole with 10

tes housing on which a motor, e.g. a compressed air operated motor, is flanged, the V / elle 12 carries a sun gear 13 rotating in bearings 15. The sun gear 13 meshes with planet gears 15, which are articulated at 16 on a circumferential web 17 which is rotatably mounted in pairs of bearings 18, 19. Comb on your part the planet gears with an internally toothed ring gear rim 20,

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which is supported by bearings 21 and cam-shaped on ssinem The circumference of the jacket has a series of curves 22.

On the cam-like circumference of the ring gear is located
a roller 23 articulated at 24 on a swivel arm 25, which swivel arm is articulated at 35 and is under the pressure of a pressure rod 26 on which a plate spring 27 acts. The plate spring 27 is seated in a sleeve 28 against which it is supported
and which in 26 is more or less screwed to the
Adjust the elongation of the spring in such a way that the desired preload is applied to the circumference of the ring gear 20
Role 23 is reached.

A sensing element 34 leans on the pivot arm 25 and controls a solenoid valve 36, which regulates the supply of the motor 11, as explained in more detail below.

The circumferential web 17 contains a longitudinally displaceable therein, however by wedges 30 non-rotatably built-in shaft 31, which on his End is provided with an insert 32 which is suitable to carry the tool that the head of the screw to be tightened or mother captured.

A spring 33 presses the shaft 31 so that it comes out of the circumferential web 17 protrudes yieldingly.

The operation of the device described can easily be derived from its construction.

"When the motor 11 is started, the circulation web 17 starts to rotate, while the ring gear rim 20 passes through the curve

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22 adjacent roller 23 is held. Then the device brought to the threaded part to be tightened, whereby the Ver ^ binding of the insert 32 of the shaft 31 to the head of the threaded part is facilitated by the resilient installation of the shaft according to an arrangement known per se. The retreat of the shaft namely allows the insert 32, the screw head or the nut to rest and to grasp them as soon as possible the mutual rotation brings the counterparts into the coupling position. In addition, the protrusion of the shaft accompanies it 31 the threaded part to be screwed in in its automatic pest control movement.

Thus, a reaction torque is applied to the ring gear rim 20 during tightening exercised by the one through the circulation bridge 1? torque applied to the threaded part to be tightened is. In particular, the torque (G) acting on the ring gear rim is a multiple of the tightening torque that is can easily be calculated on the basis of the known laws about the gear ratios of the epicyclic gears. In particular, results that the ratio between the two aforementioned torques is equal to the ratio between the number of teeth of the sun gear and ring gear.

If the sun gear 13 rotates clockwise, as can be seen in FIG. 2, does the circumferential web 1 also rotate? clockwise, while the ring gear rim 20 is subject to torque acting in an anti-clockwise direction

By appropriately setting the bias of the spring 27, the limit value of the torque G can be set, which the

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Rotation of the ring gear rim 20 and the lifting of the roller 32 at each time a curve 22 is rolled over. When the torque

G exceeds its own limit value, the rotation also exceeds it.

moment C its own limit value and the curve 22 lifts the roller 23 so that the arm 25 is pivoted and the sensing element 34- actuated which controls the valve 36 in the sense that the engine 11 is switched off. Any delay in stopping the motor, including due to inertia, affects the tightening torque C not to a significant extent, since the revolving of the ring gear rim 20 in any case stops the revolving of the revolving web 17, who cares about getting dressed.

The structure of the .Vorrichtung according to the invention in terms of Set goals can be made very compact and the compilation a set of several juxtaposed devices according to the invention for attracting slightly from one another protruding threaded parts is easily possible. The motor 11 also has a low overall height, since it generates a torque it is required that only a fraction of the tightening torque is required, after its speed is reduced by the epicyclic gear.

It has also been found that because the torque is set on the ring gear rim 20, the cetz epicyclic gear rotates slowly and that the Festsiehreaktionskraiö a: wreath with a small cash register is transmitted instead of the motor (which is also with, be it hose-like , Lines are connected), it is possible to achieve a very favorable approximation when setting the tightening torque.

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chen, so that the tightening of the screws and nuts also at the most critical conditions in the field of mechanical assembly take place within quite satisfactory tolerances can.

It is clear to a person skilled in the art that numerous changes have been made to the embodiment shown as an example in the drawing without deviating from the inventive concept.

So can the relationships between the individual, the epicyclic gear forming gears are changed, and the ring gear rim 20 with a preselected, adjustable torque braking Organ can be formed differently.

Other Aasführungformen and arrangements can also adopt the sensing element, which switches off the engine at the moment where üich the ring gear ring detaches from the braking element, v / whether the type of sensing element depends on the type and type of drive selected is.

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Claims (3)

P-A ΤΕΝΤΑ NS P R Ü C H E 1 j device for tightening and tightening threaded parts according to a preselected torque, characterized in that it comprises a motor which drives a non-rotatable pinion which meshes with planet gears of an epicyclic gear; which are carried by an epicyclic web which is fixed with a member connected that is intended _? to fit into the threaded part to be screwed in ^ whereby the planet gears also mesh with a rotating ring gear ring, on which member braking means act with a preselected torque, while sensing elements are also provided for rotating the ring gear ring, which stop the supply of the drive motor at the moment when the Ring gear begins its rotation against the braking means mentioned. 2. Apparatus according to claim 1, characterized in that the jacket circumference of the ring gear rim is cam-like and at least one curve is on v / e, on which jacket circumference a cam roller is pressed on by resilient means, the aluminum braking element serves. 3. Apparatus according to claim 2, characterized in that the? Ühl member for the rotation of the ring gear ring responds to the movement of the aforementioned cam roller, 609885/0300 ORIGINAL INSPECTED Blank