DE102017223148A1 - Process for process control in screwing processes - Google Patents

Abstract

A method for process control in screwing processes is given. In the method, a connecting element (1) having a thread (4), a component and a measuring unit for detecting a torque and / or a force, in particular for detecting a torque in dependence on a rotation angle and / or a force in dependence Way, provided. By means of the measuring unit, the connecting element (1) is connected to a component in a screwing process by measuring the torque and / or the force as a function of the angle of rotation and / or the path. The component (6) and / or a further component (7) in contact with the component (6) has at least one marking point formed as an overcoming obstacle. The reaching of the marking point during the screwing process is detected by the measuring unit, and the residual screwing distance to be covered from reaching the marking point until a predetermined final tightening torque is reached is taken into account during the screwing process.

Description

A method for process control in screwing processes is given. In the show process, a connection element, such as e.g. a screw or a nut connected to at least one component.

For fastening components, in particular in safety-relevant components, the so-called EC screwing technology (EC, "electronic control") is used. This allows the screwing process to be monitored and a conclusion drawn on the quality of the screw connection created. Usually, the process-monitored screwing process is represented by means of two independent measured variables, namely the torque and the angle of rotation. A certain residual uncertainty remains, however, since it is usually not the headrest of the screw on the component and / or the lack of an attachment can be detected.

In the prior art, in particular so-called CAT A Fittings - in the case of which there is danger to life and limb - are recorded and the screwing process monitored for process safety.

The monitoring takes place on the one hand via a geometrically defined and standardized connection element, a screw or a threaded nut, and on the other hand on the necessary measurement technology. Usually, an EC screwdriver is used for this purpose. The system records the torque over the rotation angle, which are regarded as independent variables and can make a statement about the quality of the connection.

The 1A shows schematically the recording of the system of a hard screwing, which can be assumed to be reliable. A first area A created by the insertion torque of the screw thread into the nut thread. In a hard screwing (inelastic) this increases as soon as the screw is the head rest (area B ) reached, very steep and ends when the desired torque or Verschraubmoments or when reaching a predetermined final tightening torque (range C ) with termination of the torque application.

In order not to record an abundance of data, a defined torque is normally defined as a threshold, which as a trigger causes the data to be recorded. In the 1B this is shown schematically. It means " S "The threshold and" X "The start of the recording.

The problem with this surveillance system is the blind, first area A (please refer 1A) , which is below the threshold and is not included in the evaluation. Thus, irregularities remain unrecognized in this area of the screw. In addition, a tilting of the connecting element, or another type of jamming, which leads to the fact that the end torque is reached, but no statement about whether the screw head contacts the component can not be excluded.

In the 1C and 1D Two possible unrecognized errors are recorded schematically.

When screwing according to the 1C For example, could the thread have errors, or the thread flanks are damaged when screwing.

When screwing according to the 1D can not be guaranteed a tight fit of the components, since there is a risk that the torque was achieved by jamming, but the screw was screwed obliquely and without under-head contact with the clamping part, with a wrong or no clamping part.

In the in the publication DE 10 2016 205 611 A1 described method, the connecting element on at least one marking point, which is designed as a surmountable obstacle and has a defined distance from a support point of the connecting element. The reaching of the marking point during the screwing process is detected by the measuring unit, and the residual screwing distance to be covered by the marking point to the supporting point is taken into account during the screwing process.

It is a task to be solved, at least some embodiments, to specify an alternative method for process control in screwing processes, by means of which the safety in screwing processes can be increased and, for example, the absence of attachments can be detected.

This object is achieved by a method according to the independent claim. Advantageous embodiments and further developments of the method will be apparent from the dependent claims, the following description and from the drawings.

In the method for process control in screwing processes described here, a connection element which has a thread and a component with which the connection element is to be connected are provided. Furthermore, a measuring unit for detecting a torque and / or a force is provided. Preferably, the measuring unit for detecting a torque in dependence of a rotation angle and / or for detecting a force in response to a path is formed.

The connecting element is connected to the component in a screwing process by measuring the torque and / or the force as a function of the angle of rotation and / or the path, wherein the measurement takes place by means of the measuring unit. The connecting element may be e.g. to trade a screw.

The component and / or another component in contact with the component has at least one markable point formed as an overcoming obstacle, in particular as an insurmountable obstacle for the screwing process. Preferably, reaching the marking location can be detected during the measurement, e.g. by a significant change, in particular a significant increase in the measured torque. The further component may be e.g. to act an attachment or clamping part.

The marking point can thus be designed such that during the screwing process the required screwing force or the required torque increases from reaching the marking point. Achieving the marking can be done, for example, when the connecting element reaches the marking of the component or the other component during the screwing the component or touches for the first time.

Preferably, from the detection or reaching the marking point, a defined or known residual path of the connecting element is traversed until the correct screw connection is reached or until a contact point of the connecting element has an end position, in particular by contact with or support on the component and / or further Component has reached. Preferably, after the completion of the screwing process, the connecting element contacts the component and / or the further component with the support point.

For example, the support point may be a lower head side of a screw head of a screw.

The reaching of the marking point during the screwing process is detected by the measuring unit. In particular, the measuring unit may detect reaching the overcoming obstacle, e.g. by an increase in the screwing force and / or the torque to be expended.

Preferably, the remaining screwing distance to be covered from reaching the marking point until reaching a predetermined final tightening torque is taken into account during the screwing process. In particular, the Restschraubweg to be covered by the marking to the support point during the screwing process can be considered. For example, the remaining screwing distance to be covered can be measured during the screwing process or following the screwing process. Alternatively or in addition to the consideration of the Restschraubwegs during the screwing, for example, a subsequent evaluation of the screwing done by means of data recorded by the measuring unit, in particular as to be traversed residual path is known.

By means of the method described here can be ensured by additional measures increased security in the screwing. Furthermore, for example, the absence of attachments can be detected. The detection of an existing screw head support or the lack thereof can be ensured by correlation of the applied torque in combination with the completed Restschraubweg from reaching the defined marking point. In addition, it is possible to provide during the screwing process from reaching the marking a purely Drehwinkel- and / or screw path controlled suit. The torque and the force are no longer required as control variables. As a result, friction inclusions can be excluded.

According to a further embodiment, the connecting element is designed as a screw. In particular, the connecting element may have a screw shaft and a screw head connected to the screw shaft. The screw head has a lower head side, wherein a support point is formed by the lower head side. When terminating the screwing, the lower head side of the screw head is preferably on the component and / or on the other component. Furthermore, the connecting element may be formed as a self-tapping screw. Alternatively, the connecting element is designed as a nut or as a connecting part with a nut thread.

According to a further embodiment, the screwing force to be expended during the screwing process and / or the torque to be expended during the screwing process increases by at least 10% on reaching the marking point. The screwing force expended during the screwing process and / or the torque to be expended during the screwing process preferably increases by at least 25%, particularly preferably by at least 50%, when the marking point is reached.

According to a further embodiment, the marking point is formed in a thread of the component and / or in a thread of the further component. The marking point can be, for example, a notch in the thread of the component and / or of the further component. Furthermore, the marking can be formed as a bulge in the thread of the component and / or the other component. Furthermore, the marking point or bulge can be designed, for example, as an adhesive and / or securing point in the thread of the component and / or of the further component. In general terms, the marking point may be a defined geometric deviation at a specific point of the thread of the component and / or of the further component, which, for example, has a defined distance from the contact point. The marking point can be generated either directly during the production of the component or of the further component or subsequently after the actual production process of the component and / or of the further component.

According to a further embodiment, the marking point is formed on a surface of the component and / or of the further component. For example, the marking point may be formed as an element projecting from a surface of the component and / or of the further component. The projecting element may be, for example, local elevation or bulge or embossment.

According to a further embodiment, the marking point is a locally changed hole geometry of a hole in the component and / or in the further component. For example, the hole geometry of the hole may be locally narrowed, so that when screwing a fastener or a screw into the hole of the screw resistance increases temporarily at this point.

According to a further embodiment, the marking point is an area in the component and / or in the further component, which has a different material and / or a different density compared to adjacent areas.

According to a further embodiment, the connecting element is connected in the screwing process with a component which is in contact with another component. The further component may be e.g. to act around a dome or a spring ring. The reaching of the marking can be given, for example, in a first contact of the connecting element and / or a support point of the connecting element with the other component. The dome-shaped further component may e.g. be executed with or without its own thread. Before the screwing or connecting process, e.g. between the calotte executed as a further component, a cavity may be arranged, which may be eliminated during the screwing or after the finished screwing process.

According to a further embodiment, the torque to be expended during the screwing process increases by at least 0.5 Nm when the marking point is reached. The torque to be expended during the screwing process preferably increases by at least 3.0 Nm, particularly preferably by at least 5.0 Nm, when the marking point is reached.

According to a further embodiment, the screwing force expended in the screwing process and / or the torque to be expended during the screwing process decreases again after the marking point has passed. In particular, the expended screw force or the torque to be expended after overcoming the overcome obstacle, which is formed by the marking point, and before reaching a final tightening torque decrease again. For example, the screwing force to be expended during the screwing process and / or the torque to be expended during the screwing process may decrease by at least 10% after passing through the marking position. Preferably, the screwing force expended during the screwing process and / or the torque to be expended during the screwing process, after passing through the marking point, decreases by at least 25%, particularly preferably by at least 50%.

According to a further embodiment, the torque to be expended during the screwing process decreases by at least 0.5 Nm after passing through the marking point. The torque to be expended during the screwing process preferably decreases after passing through the marking point of the marking location by at least 3.0 Nm, particularly preferably by at least 5.0 Nm. As a result, a definite criterion for determining the threshold value can be obtained via a torque difference.

According to a further embodiment, no further control variables are used in the screwing process, in particular from the time the marking point is reached, as the control variable for the screwing process in addition to the angle of rotation and / or the screwing path. By a pure angle-controlled or screw-controlled suit advantageously friction influences can be excluded.

According to a further embodiment, the connecting element has no marking point. In particular, the connecting element may be a commercially available connecting element, such as a screw or a nut. The connecting element can Thus, be designed so that it is in an undamaged state in a screwing process in which the connecting element is bolted to a component without Markierstelle until reaching the final torque no significant change in torque.

In accordance with a further embodiment, the residual path of the connecting element to be traversed from reaching or detecting the marking position is at least 5.0 mm, preferably at least 10.0 mm, until reaching the nominal end position.

According to a further embodiment, data of the screwing process, in particular the torque and / or the force as a function of the angle of rotation and / or the path, are recorded or stored electronically as soon as the marking point is reached or detected. This can be advantageously avoided that the entire screwing process must be recorded.

By the method described here, a reliable screw connection is possible. Furthermore, errors in a screw connection, such as a missing or a wrong attachment, can be detected. Especially for CAT A Fittings are a more meaningful monitoring of the screwing possible.

• 1A bis 1 D Schraubprozess-Diagramme bei Schraubprozessen gemäß dem Stand der Technik, und
• 2 ein Schraubprozess-Diagramm bei einem hier beschriebenen Schraubprozess gemäß einem Ausführungsbeispiel, und
• 3 eine schematische Darstellung eines Verbindungselements und eines Bauteils gemäß einem weiteren Ausführungsbeispiel.

Further advantages and advantageous embodiments of the method described here for process control in screwing processes will become apparent from the following in connection with the 1A to 3 described embodiments. Show it:

• 1A to 1 D Schraubprozess diagrams in Schraubprozessen according to the prior art, and
• 2 a Schraubprozess diagram in a screwing process described here according to an embodiment, and
• 3 a schematic representation of a connecting element and a component according to another embodiment.

In the exemplary embodiments and figures, identical or identically acting components may each be provided with the same reference numerals. The illustrated elements and their proportions with each other are basically not to be considered as true to scale. Rather, individual elements can be shown exaggeratedly thick or large in size for better representability and / or better understanding.

The 1A to 1D show the previously described screwing processes according to the prior art, in which a tight fit of the components can not be guaranteed, since there is the possibility that the torque was achieved by jamming, the connecting element or the screw but obliquely and without under-head contact with Clamping part, with a wrong or no clamping part was screwed. Furthermore, it can not be determined whether the thread of the connecting element has errors or whether thread flanks have been damaged when screwing in the connecting element.

Thus, especially due to the "blind" area A - Errors remain undetected and a sufficient process reliability can not be fully guaranteed. Furthermore, it can not be checked whether another component, such as an attachment or a clamping part, were properly or even attached.

2 shows a schematic representation of a described screwing process according to an embodiment.

In this case, a connecting element which has a thread, a component with which the connecting element is to be connected and a measuring unit for detecting a torque as a function of the angle of rotation are provided.

The connecting element is connected to the component in a screwing process by measuring the torque as a function of the angle of rotation, wherein the measurement is performed by means of the measuring unit. The connecting element may be e.g. to act a screw or a nut.

In addition, on the component side, a marking point can be formed as an obstacle that can be overcome during the screwing process. This marking is intended to have a defined distance to a support point of the connecting element. The marking must be designed so that the torque at this point significantly and measurably changed, preferably increases. This allows the measuring unit to detect the reaching of the marking. From this marking point is now still a defined residual path covered to the support point of the connecting element.

The marker can be the measurement as a constraint and possible starting point X serve the record. It is also conceivable to create two process windows, wherein the marker represents another constraint. It is also conceivable to continue the tightening of the screw connection from reaching the marking point in an angle-controlled manner.

By the described method, the process reliability of the screwing increases, since further errors, such as the lack of attachments, the screw with a wrong component, or a skewing of the connecting element can be detected.

For example, the marking point may be a notch in the component. Equally conceivable would be the expression of a bulge. A glue dot is also conceivable. The marking point can be designed as a defined geometric deviation at a position of the component. Furthermore, the marking location may be defined as a defined geometrical deviation in another component, such as e.g. a clamping part which is in contact with the component may be formed. Preferably, the feature has a defined distance to a support point of the connecting element.

After reaching the marking point, the torque can decrease again in order to obtain a definite criterion for threshold value determination via a torque difference.

In the 3 is a schematic representation of a connecting element 1 , a component 6 and another component 7 shown according to an embodiment. The connecting element 1 is designed as a screw and has a thread 4 and a screw head with a support point 3 on.

The other component 7 is designed as a dome with a protruding, dome-shaped part and has a hole 5 on, through which the screw 1 for connecting to the component 6 to be led.

Before the screwing is between protruding, dome-shaped part of the other component 7 and the component 6 a cavity 2 educated. The projecting, dome-shaped part of the other component 7 forms a marker. Reaches the support point during the screwing process 3 the screw 1 the marking point, then this reaching the marking point can be detected by the measuring unit, since the measured torque increases significantly when reaching the marking point.

Subsequently, from the reaching of the marking a predetermined Restschraubweg be covered, so that a correct screw can be ensured.

Advantageously, the method described here brings increased security in screwing.

The features described in the embodiments shown may also be combined with each other according to further embodiments. Alternatively or additionally, the embodiments shown in the figures may have further features according to the embodiments of the general description.

LIST OF REFERENCE NUMBERS

1

connecting element

2

cavity

3

support point

4

thread

5

hole

6

component

7

another component

A, B, C

Schraubprozessabschnitte

S

threshold

X

Start the recording

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102016205611 A1 [0011]

Claims (15)

Method for process control in screwing processes, comprising the following steps: - providing a connecting element (1) having a thread (4), - providing a component (6), - providing a measuring unit for detecting a torque and / or a force, in particular for detecting a torque as a function of a rotational angle and / or a force as a function of a path, - connecting the connecting element (1) to the component (6) in a screwing process by measuring the torque and / or the force as a function of the angle of rotation and / or the path by means of the measuring unit, characterized in that - the component (6) and / or a further component (7) in contact with the component (6) has at least one marking point formed as a surmountable obstacle, - reaching the marking position during the Tightening process is detected by the measuring unit, and - from the reaching of the marking until reaching a given Endanzugsdrehmoments zurückzulegende Restschraubweg is taken into account during the screwing process. Method according to Claim 1 in which the screwing force expended in the screwing process and / or the torque to be expended during the screwing process increase by at least 25% upon reaching the marking point. Method according to one of Claims 1 or 2 in which the torque to be expended during the screwing process increases by at least 1.0 Nm when the marking point is reached. Method according to one of Claims 2 or 3 , wherein the expended during the screwing screwing and / or expended during the screw torque after passing through the marking (2) decreases again. Method according to one of the preceding claims, wherein the marking point is formed in a thread of the component (6) and / or in a thread of the further component (7). Method according to Claim 5 , wherein the marking is formed as a notch or bulge in the thread of the component (6) and / or the further component (7). Method according to one of Claims 1 to 4 , wherein the marking is formed as from one surface of the component (6) and / or the further component (7) projecting element. Method according to Claim 7 , wherein the projecting element is designed as a local increase or embossment. Method according to one of Claims 1 to 4 , wherein the marking is formed as a locally changed hole geometry of a hole in the component (6) and / or in the further component (7). Method according to one of Claims 1 to 4 , wherein the marking is formed as a locally changed hole geometry of a hole in the component (6) and / or in the further component (7). Method according to one of Claims 1 to 4 , wherein the marking point is formed as an area in the component (6) and / or in the further component (7), which has a different material and / or a different density compared to adjacent areas. Method according to one of Claims 1 to 4 , wherein the further component (7) is formed as a dome or as a spring ring, wherein, for example, regions of the further component (7), which are touched during the screwing process first by the connecting element (1), are designed as a marking point. Method according to one of the preceding claims, wherein the connecting element (1) is designed as a screw. Method according to one of Claims 1 to 6 , wherein the connecting element (1) is designed as a nut. Method according to one of the preceding claims, wherein in the screwing process from the reaching of the marking point as a control variable for the screwing next rotation angle and / or Schraubweg no further control variables are used.

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