K35 P4PCT LG/KOE

Device for Adjustment of Points of Measuring.

The present invention relates to a device for adjustment of points of measuring in fixtures into the desired position.

Technical Field in which the Invention is Intended to Act and Prior Art:

Upon fixation of details for welding, measuring, mounting, etc., there are several methods to adjust the points of measuring into the correct position.

In order to unambiguously lock a detail in the space, it has to be locked in six degrees of freedom. The six degrees of freedom can be divided into three translations along the X, Y, Z axes and three rotations around the X, Y, Z axes.

When measuring up parts, fixtures are used to create reference points in order to lay out the details in an unambiguous way. If the details are large and weak, many points are needed. A fixture may have from three to more than twenty reference points. Each point can guide in one, two or three axes. The requirements of adjustment accuracy may be less than 0,1 mm.

Given said requirements, it is essential that it is easy to attain correct tolerances and that it can be made quickly, since there may be involved many axis directions to be adjusted by high precision.

Here, there is a selection of solutions applied today:

Shim box :

The solution is based on the fact that a joint is constructed in the direction where there should be trimming allowance and that may vary in distance by either some kind of ground spacers or shims being inserted between the components that are being joined by the joint. For adjustment, either completely ground spacers are used having those intervals by which it is intended to adjust, or the spacers are ground to the correct measure. If shims are used, these may be combined in a number of different thicknesses so that the correct measure is obtained. In one joint, it is possible to combine several adjustment directions by having spacers in all these.

The disadvantages of this type of solution are many. If shims or completely ground spacers are used, these have to be kept in stock so that they are available at the instant of time for adjustment. If spacers are ground to the correct measure, equipment as well as staff for grinding need to be available. If more than one direction in a joint is combined, good knowledge about how these joints function is required in order to be able to adjust in one direction without affecting the joint in another.

This solution is intricate and time-consuming.

Adjusting screw:

A simple solution is based on the supporting shoulder being adjusted in guiding direction by simply screwing it up or down in a thread.

Disadvantages are that it is only possible to adjust the shoulder in one direction, as well as that the shoulder is not rotationally secured.

In certain cases, screws are used with jam nuts in order to both adjust and lock the fixations. This method is useful in those cases where it is only needed to adjust in one direction. Therefore, the method has limited application.

Mechanical joint:

The solution is based on the fact that after having released the joint, the shoulder is gently "knocked" into the correct position in those directions that are to be adjusted. Often, both orientation and position are combined in these types of joints .

The disadvantages of this type of adjustment solution are that it is very difficult to achieve close tolerances, as well as the fact that it is very time-consuming to adjust the shoulder into the desired position. If position is combined with orientation in the same joint, the process becomes even more difficult. A usual method for adjustment of points of measuring is adjustment via different forms of friction joints where first a screw joint is loosened, and then the guide that should be changed is "knocked" into a new position, and after that the guide is locked by tightening the friction joint. This method

is uncertain and time-consuming. Often, there are errors in other directions than in the direction intended to be adjusted.

The Present Invention

The device according to the present invention is essentially characterized in that one axis at a time can be adjusted via one or more guide systems, which are integrated guide systems having form locking of five degrees of freedom together with a friction-locked degree of freedom.

In the drawings, fixture parts are shown in different views, wherein;

Fig. 1 shows in perspective an assembled fixture joint as seen obliquely from below,

Fig. 2 shows in planar view the fixture joint as seen from different directions, Fig. 3 shows a section view as seen along the line B-B in Fig. 2,

Fig. 4 shows a section view as seen along the line C-C in Fig. 2, and

Fig. 5 shows a section view as seen along the line D-D in Fig. 2.

The solution consists of providing a joint 1 for fixtures 20 where one axis at a time is adjusted. The adjustment consists of one or more guides 2, 3, 4, which are assembled in order to be possible to be adjusted one degree of freedom at a time. In order for a guide to be unambiguously fixed, it needs to be guided in six axes. In the present systems, the axes are form- locked in five directions and friction-locked in one direction. The friction locking 5 is made in such a way that the locking

force through wedge action creates a high frictional force in relation to the applied locking force. Upon adjustment, a locking wedge 7 in question is slightly released, so that the locking action ceases. By a set screw 9, the belonging guide 2, 3 is adjusted into the desired position. After the adjustment, the locking wedge 7 is tightened again.

An example of such a design may be a system including a guide 2-4 having a dovetail-shaped track, below denominated dovetail track. That is, two wedge-shaped surfaces 10, 11 where one of the wedges 10 surrounds the other 11. In order to improve the stability, it is possible to remove the intermediate part of the surfaces so that they only abut in the ends. For small parts, this is not necessary, since it is easy to manufacture them by such a precision that the intermediate part does not impair the guiding in the ends of the track contact. In the described example, the guide runs in a dovetail track. On one side, the V-shape of the guide is pressed against the fixed V- shape β. On the other side, a movable wedge 7 enters and locks the upper plane of the guide against the fixed upper plane of the wedge .

Depending on the angle of the wedge, different division is obtained between the locking force in the direction of friction and the stiffness perpendicular to the direction of friction.

In the present joint 1, several methods coincide to a common method wherein adjustment by friction joints is combined with a set screw 9 in each guiding direction.

The present joint 1 has also the advantage that it is possible to adjust the points of measuring rather exactly, quickly and easily. By the fact that the different sliding blocks of the

present joint 1 always are locked against each other in a robust way, via stable surfaces 10, 11 of the opposite sliding block, great repeatability and high accuracy are obtained in the adjustment.

The present joint 1 is considerably more compact than other previously used systems/components.

The design of the present joint is characterized in that the locking of the sliding blocks is effected by the sliding blocks being wedged up against each other via a "dovetail profile". There are two butting profiles in each guiding direction. The locking is effected by the fact that a part of a side of one of the profiles consists of a loose wedge 7, which is pressed into the wedge track 12 on the opposite side of the opposite sliding block 2. The pressing-in of the loose part/wedge 7 is effected by a screw 8 being pulled through the part into one of the sliding blocks. When the screw 8 is tightened, the wedge 7 locks the opposite sliding block to the sliding block in which the wedge is screwed. Upon adjustment, the wedge 7 is slightly loosened and the adjusting screw 9 of the opposite sliding block is turned in different directions for each guiding direction.

In the drawings, different views of parts are shown, which are included in a fixture 20 according to the invention and having the respective end formed as a comb-shaped coupling part and as a plane part, respectively. The different fixture parts may be arranged right-angled in relation to each other and/or at another selected angle between 0-90°. They may also be arranged in a desired number of planes.