DD227907A1 - METHOD FOR FILLING WORKPIECES BY PRESSFILMING - Google Patents

Abstract

The invention relates to a method for joining workpieces by interference fit, in which a workpiece is inserted into the other by means of a press ram under the action of a Fuegekraft by a Fuegehub. The aim of the invention is the automatic separation of workpieces or workpiece pairs according to quality features with regard to the frictional connection. Depending on the task, the quality features of the workpiece pairings in the filled or unfilled state should be recognizable from the process sequence of the joining process after certain process steps. The task is solved in that different staggered Fuegekraefte acting on their respective times successively act on the workpiece to be fufende, from executed Fuegehuben, in conjunction with the applied Fuegekraft a quality signal is formed, which the control of an industrial robot zugefuehrt a differentiated storage of the workpiece pairings or unfinished workpieces according to quality groups.

Description

- 2 - Upper Austria Jl

Pmax takes place, wherein the joining force P _max corresponds to the joining force, as required for joining a press fit with maximum oversize and that when executed joining stroke in conjunction with the applied joining force P _n a quality signal is formed after the workpieces in the joined state after Matching qualities are sorted.

embodiment

The invention is explained in more detail below with reference to a preferred embodiment.

On a hydraulic press a sprocket and a shaft are to be combined automatically in larger quantities in a press fit. The supply and removal of the parts is done with the help of an industrial robot.

With a nominal diameter of the parts to be joined of 100 mm, the parts range contains workpieces with different dimensions within the tolerance range as well as workpieces that exceed or fall below the tolerance range. If the bore of the gear rim is K7 and an associated shaft fit is Z8, the smallest excess is +26 μ and the largest excess is +50 μ.

The workpiece pairings within these dimensions can be added. But they have different qualities depending on the actual dimensions in terms of their frictional connection and are therefore more or less resilient.

Workpiece pairings with an excess of <+ 26μ will be able to be fitted, but no interference fit will result. The workpieces are joined together after joining in a moving seat and must be rejected with the quality criterion "Committee" The workpiece pairings, which have an excess of> +50 μ, can no longer be added ,

In summary, the following quality groups result:

Oversize <+26 μ - scrap

Oversize 26-30 μ-usable

Oversize 31-40 μ-well

Oversize 41-50 μ-very good

Oversize> 50 μ - rework

For joining the workpiece pairs within the assigned quality groups different joining forces are required. The joining force shall be calculated in such a way that the largest excesses of a quality group are the basis of the calculation, giving the following classification:

Oversize <+ 26 μ - joining force P ₁

Oversize 26 - 30 μ - joining force P ₂

Oversize 31 -40 μ - Joining force P ₃

Oversize 41 - 50 μ - joining force P ₄

Oversize> 50 μ - joining force P ₅

Each joining force acts within the process a certain time t, to t ₅ on the workpieces, which is such that in this time the addition can be made. During joining, the press ram executes the joining stroke. A fully executed ram stroke is thus a feature of a performed joining at a certain joining force P ₁ to P. ₅

An unfinished joining stroke causes, according to the method, an increase in the joining force to the joining force for the next higher quality group.

Each executed joining stroke, in conjunction with the joining force which has been effective, serves to form a quality signal which, fed to the control of the industrial robot, results in a differentiated deposition of the workpiece pairings or unfixed workpieces according to the quality groups mentioned.

The process sequence is described in more detail below for three workpiece pairs with different degrees of oversize.

1. Workpiece pairing with oversize +20 μ

- The press ram acts over the time t, with the joining force P ₁ on the workpiece to be joined.

- The joining stroke is executed.

- The execution of the joining stroke leads in conjunction with the statement about the joining force P _{1 used} to form the quality signal "Committee".

- The industrial robot removes the workpieces from the press and leads them to a depository for rejects.

2. Workpiece pairing with oversize +35 μ

- The press ram works over time t! with the joining force P ₁ on the workpiece to be joined.

- The joining stroke is not executed.

- The joining force is increased after the time t, P ₂ , which is effective over the time t ₂ .

- The joining stroke is not executed.

- The joining force is increased after the time t ₂ to P ₃ , which is effective over the time t ₃ .

- The joining stroke is executed.

- The execution of the joining stroke leads in connection with the statement about the used joining force P ₃ to the formation of the quality signal "good".

- The industrial robot removes the workpieces from the press and delivers them to a berth for parts with the quality feature "Good".

3. Workpiece pairing with oversize +60 μ

It follows up to the action of the joining force P ₃ over the time t _3, the same procedure as in the second embodiment.

- The joining stroke is not executed.

- The joining force is increased after the time t ₃ to P ₄ , which is effective over the time U.

- The joining stroke is not executed.

- The joining force is increased after the time I ₄ to P ₅ , which acts on the time t ₅ .

- The joining stroke is not executed.

- The non-execution of the joining stroke leads in connection with the statement about the used joining force P ₅ to the formation of the quality signal "rework".

- The industrial robot removes the workpieces from the press and delivers them to a berth for parts with the quality feature "rework".

-3- 688

The technical-economic effect of the invention is that the procedure for joining the interference fit simultaneously conveys statements about the quality characteristics of the fits. Thus, the press is used as a quality testing device, which makes it possible to signal workpiece pairings that do not correspond to the corresponding fit qualities and weed them out as a committee or supply a rework.

Within paired workpiece pairings a differentiated quality recognition becomes possible.

This is particularly important in automatic processes in which the workpiece pairings in the workpiece flow are fed to further processing stations or assembly stations.

Another advantage of the invention results from the fact that no special test equipment is required for testing bonded workpiece pairings. There is an ongoing control over the quality of the fit fits. In the case of an accumulation of reduced quality features, it is possible to influence the prefabrication.

Claims (2)

-1- 688 Invention claims: 1. A method for joining workpieces by press fitting, in which a workpiece is inserted into the other by means of a press ram under the action of a joining force through a joining stroke, characterized in that the press ram with a joining force P, over a time t, to the mating workpiece acts in which it is waited whether the joining force P, is sufficient to push the workpieces to be joined together, that the joining force P _{1 is increased} to a higher value P ₂ , if no joining stroke is done by the joining force P _t and that, when the joining stroke is carried out under the action of the joining force P ₁ , and when the joining stroke is not performed under the action of the joining force P ₂ over a time t _2, a separation of the workpieces according to quality features with respect to the frictional connection, wherein the joining force P _{1 is} dimensioned slightly smaller than the necessary joining force P _min for a press fit with minimal oversize and the Joining force P ₂ corresponds to the joining force, as it is necessary to join a press fit with a differentiated upper dimension. 2. The method according to item 1, characterized in that the increase in the joining force in several stages between P _min and P _ma »takes place, wherein the joining force P _{mix of} the joining force, as required for joining a press fit with maximum excess and that at executed joining stroke (h) in conjunction with the applied joining force P _n a quality signal is formed, after which the workpieces are sorted in the joined state according to fit qualities. Field of application of the invention The invention relates to a method for joining workpieces by press fitting, in which a workpiece is inserted into the other by means of a press ram under the action of a joining force through a joining stroke. Characteristic of the known technical solutions The joining of workpieces by press fits is in the most general form in that a cylindrical workpiece, such as a bolt or a shaft, is pressed into a bore which is located in another workpiece. It is also possible to press the workpiece having the bore on the mandrel or the shaft. The tolerance range of such a press fit is chosen so that the workpieces sit firmly together after joining and are suitable due to this form fit to transfer forces from a workpiece of the workpiece pairing on the other. The size of the transferable forces depends primarily on the fitting dimensions, so that within a given tolerance range very different fit quality features are present. These quality features are not readily apparent in a joined workpiece pairing. To determine this, the mating would have to be tested under load to slip or break, destroying the mating. The joining process itself, is known, characterized in that a workpiece in the other with the help of a press ram under the action of a joining force by a joining stroke on or postponed. The joining force is essentially dependent on the dimensions of the cylinder surfaces involved in the pairing. Within a given tolerance range, there are three possibilities for the joining process. If the excess of the fit exceeds the tolerance limit, the first possibility is the fact that the workpieces can not be joined. The shaft can not be inserted into the hole. The second option detects all dimensional conditions within the tolerance range. This is a nesting possible, albeit with different quality in terms of frictional connection. Falling below the tolerance range results in a third possibility, a state in which the workpieces are joined together, but not in a press fit, but in an unintentional movement seat. In order to join workpieces within the scope of the second possibility, it is known to adapt the joining force of press rams to the assembly conditions. From DD-PS 129 033 B 23 P 19/02 an example is known, according to which the operating pressure of the working cylinder from zero to P _{max is designed to be} adjustable. According to DD-PS 208 042; B 23 P 19/02 the pressing force is corrected according to the workpiece diameter and the materials used. However, the per se known controllability of the joining force is used according to the method only to adapt to a certain fit quality with a given tolerance range. The workpiece pairing comes about either after the said second possibility or unassembled, or too loosely joined workpieces must be discarded. In particular, the separation prepares for automated workflows special measures in terms of detection. The pairs of workpieces joined according to the second possibility are sent to further use without knowledge of their fitting qualities. Object of the invention The aim of the invention is, with the help of the process sequence, to effect an automatic rejection of workpiece pairings which exceed or fall short of the tolerance range of the press fit to be joined, and to enable a sorting of joined press fits according to quality features of their adhesion. Explanation of the essence of the invention The invention has the object of providing a method for joining workpieces by press fitting, in which a workpiece is inserted into the other by means of a press ram under the action of a joining force through a joining stroke, inventively further develop, so that from the procedure for certain process steps the Identify quality features of the workpiece pairing in the joined or unfilled state. According to the invention this is achieved in that the press ram with a joining force P ₁ over a time t! acting on the workpiece to be joined, in which it is waited whether the joining force P _{1 is} sufficient to push the workpieces to be joined together, that the joining force P _{1 is increased} to a higher value P ₂ , if no joining stroke by the joining force P ₁ is carried out and that when performed joining stroke under the action of the joining force P ₁ , and when not performed joining stroke under the action of the joining force P ₂ over a time t _2, a separation of the workpieces according to quality characteristics with respect to the frictional connection, wherein the joining force P _{1 is} dimensioned slightly smaller , as the necessary joining force P _min for a press fit with minimal oversize and the joining force P ₂ corresponds to the joining force, as it is necessary for the addition of a press fit with differentiated excess.
An embodiment feature of the invention is that the increase in the joining forces in several stages between P _min and