DE102017223589A1 - Method for mounting a screw, mounting device and control device - Google Patents

Abstract

The invention relates to a method for mounting a screw using a torque sensor and an angle sensor, characterized in that the screw is screwed in to a target torque (32) and from a threshold torque (24) senses a rotation angle of the screw when screwing and / or determined In addition, the invention relates to a mounting device. In addition, the invention relates to a control device

Description

The invention relates to a method for mounting a screw using a torque sensor and an angle sensor.

It is known to tighten the screws during assembly to a pre-torque, and then tighten the screws by a target angle with monitoring of a resulting end torque. By using the pre-torque, it is to be ensured that the dispersion of the resulting end torque is reduced in comparison with a sole use of a target angle.

In addition, it is known to perform the screw torque controlled and yield limit controlled.

However, it has been found that errors can occur even when using the pre-torque. This can lead to setting operations of the screw. These take place in the setting and joining area, which follows the insertion area. In the following uniformity range occurs when switching from torque control to angle control at a moment in which the assembly tool is de-energized. This results in inaccuracies in the resulting end torque, as well as its rating and the angular start and acting on the screw Nachdrehwinkels, also called target angle

Proceeding from this, it is an object of the present invention to provide a method for mounting a screw, in which the scattering of the threshold torque or pre-torque and the resulting end torque is further reduced.

To solve this problem, it is proposed that the screw is screwed in to a target torque and senses a rotation angle of the screw when screwing in and / or determined from a threshold torque. In the known procedure, no angle adjustment is made until the predetermined torque is reached. It is therefore basically a torque-controlled screwing the screw. As a result, there is no suspension of torque. By measuring the angle, however, a plausibility check of the screwing-in process can take place. As the core of the invention is therefore considered that, at least temporarily, a simultaneous sensing of torque and angle of rotation takes place and still exists a continuous propulsion.

Preferably, the simultaneous sensing of torque and angle of rotation takes place from a threshold torque which is smaller than the target torque or resulting final torque and greater than zero.

The screw is thus screwed in continuously and without interruption up to the defined target torque. From the given threshold torque and the rotation angle is measured to the target torque.

Advantageously, upon reaching and / or exceeding the predetermined torque, the angle of rotation can be compared with at least one predetermined angle of rotation threshold. In this way it should be ensured that the sensed torque does not come about by a standing in the way degree or the like but is defined by the tightening position of the screw.

Depending on the procedure, the screw connection can be classified as faulty in one embodiment when the rotary angle threshold value is exceeded or fallen short of. In particular, the screw connection can be classified as faulty if it falls below a lower angle of rotation threshold or if an upper angle of rotation threshold is exceeded. In this case, the assembly process is stopped and the gearbox is either rearranged, re-assembled or sorted out under supervision.

A review of possible screwing and setting influences in the screw connection are described below and can be detected and detected in these areas by a corresponding parameterization, so that these negative influences can be assessed as niO, also can be decided on a niO strategy whether a release The screw is made by such an event and the process is generally rated as NOK, or whether a loosening and repeated tightening is allowed.

Expressed differently, therefore, there is a tolerance band in which the screw is considered to be mounted error-free.

Alternatively, it can be provided that, when falling below a, in particular lower, rotational angle threshold value, the screw is tightened while sensing the torque. Assuming that the faulty torque is based on the fact that the screw is temporarily blocked, the screw can be solved by overcoming the obstacle either or subsequently tightened again. On In this way, the error rate during screwing directly in the automated screwing process can be minimized by eliminating the screwing problems in the automated screwdriving process. In this way, the number of screws to be mounted manually can be reduced.

Preferably, the screw can be screwed up to a predetermined torque at a higher speed and from the predetermined torque at a lower speed. The predetermined torque may preferably be the threshold torque, but it may also be another torque value.

Advantageously, the method is carried out when screwing a screw on a motor vehicle transmission. In particular, in motor vehicle transmissions, there may be mounting positions of the transmission, in which an inspection and manual post-processing of the screwing is very complex and difficult. Therefore, the reduction of the error rate of the screwing is very beneficial.

In addition, the invention relates to a mounting device for mounting a screw, in particular on a motor vehicle transmission, with a torque sensor, an angle sensor, a control device and a tightening device for tightening the screw. The mounting device is characterized in that the mounting device is adapted to at least temporarily sense the torque applied to the screw and the angle of rotation of the screw when screwing. The assembly is then as already described for the procedure. To avoid repetition, reference is made to the described method. The design of the machine and its operation results directly for the expert.

Advantageously, the mounting device can be checked by means of a comparison device for comparing the sensed torque and / or rotation angle with redundant transducers. For the use of the comparison devices, appropriate programs are preferably to be set up in the control device, these are to be used cyclically in order to check the accuracy of the torque and rotational angle values and thus to ensure that the device is capable of permanently and safely adhering to the default values.

In addition, the invention relates to a control device for a mounting device for mounting a screw. The control device is characterized in that it is designed to carry out the described method.

• 1 ein Ablaufschema eines Montageverfahrens,
• 2 eine Montagevorrichtung, und
• 3 ein Drehmomentdiagramm.

Further advantages, features and details of the invention will become apparent from the following description of exemplary embodiments and the figure. Showing:

• 1 a flow chart of an assembly process,
• 2 a mounting device, and
• 3 a torque diagram.

The 1 shows a flowchart of a method for mounting a screw. In step S1 The screw is automatically inserted into a mounting device. The screw can be inserted for example on a motor vehicle transmission in order to screw the clutch bell to the transmission housing.

In step S2 the screwing process is started, the torque is sensed.

In step S3 the first predetermined torque is achieved in terms of a threshold value.

From reaching the first predetermined torque is in step S4 additionally sensed the angle of rotation.

Upon reaching the target torque, the rotation angle is compared with a lower rotation angle threshold and an upper rotation angle threshold. Is the achieved angle of rotation in step S7 in the specified tolerance band, he is classified the screwing as error-free, otherwise as faulty.

In step S4 If there is no interruption of the three-phase voltage, screwing in is uninterrupted. The assembly tool is not energized at any time until reaching the target torque.

2 shows a mounting device for mounting a screw. The mounting device 1 includes a frame 2 , a control device 3 , a suit device 4 , a torque sensor 5 and a rotation angle sensor 6 ,

The torque sensor 5 and the rotation angle sensor 6 Sensing this about the tightening device 4 on a screw 7 applied torque or the induced angle of rotation. The screw 7 For example, when installing a motor vehicle transmission 8th between clutch bell 9 and gearbox 10 be used.

3 shows the torque curve during a screwing process. It is on the axis 12 the angle of rotation and on the axis 14 the torque applied.

The insertion area 16 is usually needed to bring the screws within the required cycle time on depth and head support, and should be done with the highest possible speeds. The torque-indicating curve 18 runs in this area almost linear.

Also must in the Eindrehbereich 16 In principle, it is already possible to monitor this process in order to achieve, if necessary, minimum penetration depths or to show possible cases of failure, which can be parameterized by limit values in the sense of tolerances with regard to torque and / or rotation angle.

In the following setting and joining area 20 Set and joining operations of the components included in the screw connection take place. These must be completed in order to be in the regularity area 22 to change without the required there for the final evaluation threshold 24 which could possibly fail to meet a misinterpretation of the final result and thus the quality and functional requirements.

In the uniformity area 22 find according to the invention no interruptions in the screw through screw more instead.

In the state of the art, switching parameters that occur when programming the screwdriver, for example by changing the speed between the screwing range 16 and the setting and joining area 18 or the setting and joining area 18 and the uniformity area 22 are required, a traction interruption after. These lead when changing into the following part of the screw that the tension in the system such as force attacks between the screw head and screw bit, and screw and clutches / extensions, as well as their torsional behavior to misinterpretation of the torque / angular ratio and are not rated as such qualitatively insufficient ,

Another aspect of the prior art relates in this context also the breakaway behavior of the screw in the composite, which also lead to misinterpretations depending on the environmental conditions such as surface roughness, Nachbiegigkeiten, etc. and i.d.R. As a result, the durability of the bolted composite can have a negative impact.

In the uniformity area 22 Now according to the invention, the Schwellmoment 24 without interruption of traction to the end point 26 of the final assessment area 28 defines which nominal value is the angle starting value 30 puts. The value 0 ° is set as angle start value. The angle will now be reached until the defined end torque is reached 32 in accordance with narrow limits, which can be determined empirically, taking into account the permissible Reibwertbandes and the particular peculiarities and development specifications of each Schraubverbundes set. The limit values defined in this way are, just like the angle-controlled and torque-monitored suit known from the prior art, able to bring the screw safely into the desired target corridor, without the influences such as the area of uniformity 22 described.

The swelling moment 24 for angular start as described in the control or parameterization is not specifically controlled, but only after the change in the final suit as angle zero value set. It therefore does not have its own tolerance, which, as in the case of traditional angle-controlled suits, opens up the possibility of altering it within the tolerance allowed there. The fixed value thus allows a slightly greater tolerance in the definition of the target torque, which is additionally limited by a narrow set minimum and maximum rotation angle.

In the final evaluation area 28 the end torque or target torque is defined. This is defined according to the specifications such as coefficient of friction, elastic or over-elastic suit and verified by empirical tests under series conditions. The thus defined target torque is within the requirements required for process and functional safety, by a narrow tolerance range for the out of the threshold in the uniformity range 22 and the target torque resulting rotation angle defined for this.

In the following, examples according to the prior art and embodiments according to the invention are compared.

The first example describes a known angle-controlled tightening with a pre-torque of 10Nm + 1Nm. After reaching the pre-torque, the screwdriver switches over to angle control and is thereby de-energized. This results in a draft relief. The pre-torque, which as a control variable leads precisely to the shutdown of the screwdriver, can no longer be used to detect possible influences, such as, for example. Friction values outside specifications, etc., until the torque is reached.

After reaching the pre-torque, the rotation angle evaluation is falsified by the re-tensioning of the force attacks between the screw spindle and screw head, torsion, breakaway behavior and evaluation blindness of the control unit during circuit operations. The determined angle of rotation achieved does not completely affect the screw or the tension of the parts involved in the screw connection. When proceeding according to the first example, which has already been described in the introduction, this leads to large variations in the resulting end torque.

The second example describes the procedure according to the invention. Upon reaching the threshold value 24 without control and mechanical influences of the nutrunner control parameters and in the force structure of the components used. There is no train interruption, no breakaway torque, etc. and thus lower failures, as failures in the Voranzugmomentes completely eliminated.

The in essential areas, in particular up to Voranzugsmoment or at the start in the stage of the final suit no longer taking place interruption of traction leads to a fully dynamic drive of the screw. As a result, the specific screw course of the screw connection becomes more transparent and easier to interpret in the event of a fault. So you can also verify possible causes faster in the error analysis. That The advantages of this invention thus lie in the reduction of niO glands, a faster error analysis, as well as in the robustness or improved reliability of the screw.

As a general rule, this procedure applies to all bolting applications, both for bolts and nuts.

The described areas can additionally be checked with corresponding monitoring criteria. Here are switching commands of the control, which interrupt the traction, as possible in the Eindrehbereich 16 to lay, if necessary, also to the setting and joining area 20 in order to be able to recognize large spreading widths in the course of the screw. In any case, starting from the uniformity range 22 Zugunterbrechungsfrei to target moment in the final evaluation area 28 be continuously tightened with preferably the same speed.

LIST OF REFERENCE NUMBERS

1

mounter

2

frame

3

control device

4

tightening device

5

torque sensor

6

Rotation angle sensor

7

screw

8th

Motor vehicle transmission

9

Kupplungsglocke

10

gearbox

12

axis

14

axis

16

Eindrehbereich

18

Curve

20

Setting and joining area

22

uniformity area

24

threshold torque

26

endpoint

28

Endbewertungsbereich

30

Angle start value

32

end torque

Claims (11)

Method for mounting a screw using a torque sensor and an angle sensor, characterized in that the screw is screwed in up to a target torque (32) and sensed from a threshold torque (24) a rotation angle of the screw when screwing and / or determined. Method according to Claim 1 , characterized in that the angle of rotation is compared with at least one predetermined angle of rotation threshold. Method according to Claim 2 , characterized in that when exceeding or falling below the rotation angle threshold, the screw is classified as defective. Method according to one of the preceding claims, characterized in that the screw is screwed in to a further predetermined torque with a higher speed and from the predetermined torque with a lower speed. Method according to one of the preceding claims, characterized in that the position of the angle of rotation in the predetermined tolerance band, the screw is classified as error-free. Method according to one of the preceding claims, characterized in that the screw is mounted on a motor vehicle transmission. Method according to one of the preceding claims, characterized in that the screw from a predetermined torque, in particular from the threshold torque (24) and / or in particular with the beginning of the uniformity region (22), torque interruption-free to the target torque (32) is screwed. Mounting device for mounting a screw with a torque sensor, an angle sensor, a control device and a tightening device for tightening the screw, characterized in that the mounting device is adapted to simultaneously sense the torque applied to the screw and the angle of rotation of the screw when screwing. Mounting device according to Claim 8 , characterized in that the mounting device comprises a comparison device for comparing the torque with a torque threshold. Mounting device according to Claim 8 or 9 , characterized in that the mounting device comprises a comparison device for comparing the angle of rotation with at least one angle of rotation threshold. Control device for a mounting device for mounting a screw, in particular on a motor vehicle transmission, characterized in that according to the control device for carrying out the method according to one of Claims 1 to 5 is trained.

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