Device for inserting a threaded insert into a bore

Abstract

Device for inserting a threaded insert (18) into a bore (16), with a mandrel (10) axially displaceable in a working direction (A), which has a holder (34) for holding the threaded insert (18) when inserted into the bore (16), characterized by a feeding aid which has a downpipe (26) for the threaded insert (18) and a catch (22) arranged at the lower end of the downpipe, which has a receptacle (24) for the threaded insert (18) in its circumferential wall and is rotatable about an axis extending transversely to the working direction (A) of the mandrel (10) and displaceable in a direction parallel to this axis.

Description

[0001] The invention relates to a device for inserting a threaded insert into a bore, with a mandrel axially displaceable in a working direction, which has a holder for holding the threaded insert when inserting it into the bore.

[0002] When bolts are screwed into threaded holes in workpieces made of plastic or similar materials with low tensile strength, there is a risk of the thread stripping if excessive tensile force is applied to the bolt. Therefore, instead of cutting the thread directly into the plastic material of the workpiece, a threaded insert—that is, a sleeve made of metal or another material with high tensile strength and provided with an internal thread—is often glued, welded, or otherwise securely fastened into the hole of the workpiece. The bolt to be inserted is then screwed into the internal thread of the insert.

[0003] To insert the threaded insert into the bore, an axially movable mandrel is often used. At its tip, this mandrel carries a holder for the threaded insert formed by expanding elements. Once the insert is fixed to the holder, the holder is advanced axially, causing the insert to plunge into the bore. For workpieces made of thermoplastic materials, the mandrel may, for example, have a heating element that heats the threaded insert, effectively welding it into the bore as it is inserted.

[0004] The threaded inserts are often delivered in bulk in a container and then individually removed from the container by hand and placed onto the holder of the mandrel.

[0005] The object of the invention is to simplify the placement of the threaded insert onto the holder.

[0006] This problem is solved according to the invention by a feeding aid which has a downpipe for the threaded insert and a catch piece arranged at the lower end of the downpipe, which has a receptacle for the threaded insert in its circumferential wall and is rotatable about an axis running transversely to the working direction of the mandrel and displaceable in a direction parallel to this axis.

[0007] To insert a threaded insert into a workpiece bore, the workpiece and the mandrel are positioned so that the mandrel is axially aligned with the workpiece bore. The threaded insert is then fed into the drop tube, the inner cross-section of which is matched to the outer cross-section of the threaded insert, either manually or using a vibratory feeder and singulator. The threaded insert then falls through the drop tube into the receptacle of the catch. The catch is then rotated about its longitudinal axis and moved axially into a position where the receptacle and the threaded insert it holds are axially aligned with the mandrel. The mandrel is then advanced so that the holder engages the threaded insert.Once the insert is securely held against the mandrel by spreading the holder, the mandrel is retracted and a heater integrated into the mandrel is activated to heat the threaded insert. Meanwhile, the catch returns to a position where its receptacle is aligned with the outlet of the downpipe, ready to accept the next threaded insert. The catch is then in an axial position, out of the mandrel's path of movement. When the threaded insert is sufficiently heated, the mandrel is advanced again until the threaded insert enters the workpiece bore and is welded in place.

[0008] The invention has the advantage that the threaded insert simply needs to be dropped into the upper end of the downpipe and is then guided into the catch without any operator intervention. It is then automatically aligned with the mandrel and taken over by the holder. The threaded insert can then be automatically welded in the bore as soon as the workpiece has reached the correct position relative to the mandrel. A particular advantage is that the manual process of dropping the threaded insert into the downpipe is temporally decoupled from the actual insertion process and can therefore take place even before the workpiece has reached its correct position relative to the mandrel.Since the thread insert does not need to be held by hand while it is gripped by the mandrel holder, the axial distance between the mandrel and the workpiece can be very small, so that the mandrel only needs to travel a short distance and can therefore operate at a high cycle rate.

[0009] Advantageous embodiments of the invention are specified in the dependent claims.

[0010] The downpipe may have an inlet slope at the upper end, which facilitates the insertion of the threaded inserts into the downpipe.

[0011] The catch can be mounted in a base which has a channel running transversely to the axis of the catch, through which the mandrel can be advanced to the workpiece.

[0012] The following section explains an exemplary embodiment in more detail with reference to the drawings.

[0013] They show: Fig. 1 a partially cut-away side view of a device according to the invention for inserting threaded inserts; Fig. 2 a partially cut-away front view of the device according to Fig. 1; Fig. 3 a representation analogous to Fig. 1 for a later stage during an insertion process; Fig. 4 a representation analogous to Fig. 2 for a later stage during the deployment process; Fig. 5, Fig. 6 and Fig. 7 further stages of the deployment process in a representation analogous to Fig. 1; and Fig. 8 a final stage of the insertion process in a representation analogous to Fig. 2.

[0014] The in Fig. The device shown in Figure 1 has a mandrel 10 that is axially movable in a horizontal working direction A relative to a conveyor 12, which serves to feed and position a plastic workpiece 14. The workpiece 14 has a bore 16 in its surface facing the mandrel 10, into which a threaded insert 18 is to be inserted. The workpiece 14 is positioned such that its bore 16 is axially aligned with the mandrel 10. A stationary base 20 is arranged between the workpiece 14 and the tip of the mandrel 10. This base forms a sliding bearing for a cylindrical catch 22, shown here in section. The catch 22 has a cylindrical receptacle 24 in its circumferential surface, which is dimensioned to accommodate the threaded insert 18 without play. Fig. In the state shown in Figure 1, the opening of the receptacle 24 points upwards and is positioned so that it is flush with the inner cross-section of a vertical downpipe 26. The inner cross-section of the downpipe 26 is also dimensioned such that the threaded insert 18 can be guided in this downpipe with virtually no play. In the example shown, the downpipe has a funnel-shaped inlet ramp 28 at its upper end, which facilitates the manual or machine insertion of the threaded insert 18.

[0015] In the front view in Fig. Figure 2 shows a drive 30 which serves to rotate and axially displace the catch 22. The base 20 has a semi-cylindrical channel 32 through which the Fig. 2 non-visible mandrels 10 can be moved axially onto the workpiece 14 with the bore 16.

[0016] Fig. Figure 3 shows the device in a state where the threaded insert 18 has traversed the downpipe 26 and entered the receptacle 24 of the catch piece 22. The catch piece 22 is then axially inserted into the receptacle by means of the drive 30. Fig. The position shown in Figure 4 is advanced so that the axis of the threaded insert 18 held in the receptacle 24 and the axis of the mandrel 10 lie in one plane. By rotating the catch 22 by 90°, the receptacle 24 is then brought into a position in which the threaded insert 18 is centered on the axis of the mandrel 10. (The order of the axial movement and the rotational movement is arbitrary.) The mandrel 10 has a holder 34 for the threaded insert 18 formed by spreading elements at its front end. Fig. 5) When the mandrel 10 is advanced axially towards the workpiece 14 by a drive (not shown), the holder 34 plunges into the threaded insert 18, as shown in Fig. Figure 6 shows that by spreading the spreading elements, the threaded insert 18 is then engaged by the holder 34, and by retracting the mandrel 10, the threaded insert is pulled out of the receptacle 24 of the catch 22. This state is shown in Fig. 7 shown. The catch piece 22 is then turned back and into the Fig. 1 and Fig. The starting position shown in Figure 2 is withdrawn, whereby it is understood that the rotary and axial movements of the catch 22 can also take place simultaneously or in a different sequence. By axially withdrawing the catch 22, the channel 32 is cleared so that the mandrel 10 can be advanced to the workpiece 14. As shown in Figure 2, the starting position is withdrawn, whereby it is understood that the rotary and axial movements of the catch 22 can also take place simultaneously or in a different sequence. Fig. As shown in Figure 8, the threaded insert 18 enters the bore 16 of the workpiece.

[0017] The mandrel 10 has an integrated heater which heats the threaded insert 18, as soon as it is gripped by the holder 34 and pulled out of the receptacle 24, to a temperature at which the plastic material of the workpiece 14 melts, so that the threaded insert is welded in the bore 16.

[0018] In the example shown, the mandrel 10 extends into Fig. 8 freely through the channel 32 of the base 20. Alternatively, the base 20 can also be designed so that the pin 10 is guided in the channel 32.

[0019] The length of the downpipe 26 is dimensioned so that there is no risk of injury or burns when the threaded inserts are inserted into the downpipe by hand.

Claims

[1] Device for inserting a threaded insert (18) into a bore (16), comprising a mandrel (10) axially displaceable in a working direction (A), which has a holder (34) for holding the threaded insert (18) when inserting it into the bore (16), characterized by a feeding aid comprising a downpipe (26) for the threaded insert (18) and a catch piece (22) arranged at the lower end of the downpipe, which has a receptacle (24) in its circumferential wall for the threaded insert (18) and is rotatable about an axis extending transversely to the working direction (A) of the mandrel (10) and displaceable in a direction parallel to this axis. [2] Device according to claim 1, wherein the downpipe (26) has an inlet slope (28) at its upper end. [3] Device according to claim 1 or 2, wherein the catch (22) has the form of a cylinder whose axis lies in a common plane with the axis of the mandrel (10). [4] Device according to claim 3, wherein the catch (22) is mounted in a base (20) which forms a channel (32) into which the mandrel (10) can enter.

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