WO2011056065A1

WO2011056065A1 - Device for forming a flared hoop, mandrel, method for forming a flared hoop, flared hoop

Info

Publication number: WO2011056065A1
Application number: PCT/NL2010/050683
Authority: WO
Inventors: Anton Podt
Original assignee: Fontijne Grotnes B.V.
Priority date: 2009-10-16
Filing date: 2010-10-15
Publication date: 2011-05-12
Also published as: NL2005086C2; NL2005086A

Abstract

Device for forming a flared hoop comprising an expandable mandrel (2) comprising a cylindrical body (3) with at least one flared end (4), wherein the mandrel is adjustable between a first position in which the mandrel has a diameter and a second position in which the mandrel has a larger diameter, wherein the device is arranged for positioning the mandrel in the first position in a hoop to be flared and for bringing the mandrel from the first position to the second position to provide the hoop with at least one flared end.

Description

Title: Device for forming a flared hoop, mandrel, method for forming a flared hoop, flared hoop.

The invention relates to a device for forming a flared hoop. Devices for forming a flared hoop are known. In particular, when manufacturing a rim, e.g. for tires of vehicles, one of the production steps is to provide flared ends on a hoop. The manufacturing process of a rim starts with a steel plate that is formed into a hoop. The steel plate is coiled until a hoop is formed and the edges of the plate are abutting against each other. The abutting edges are welded together. However, before welding the edges together, the edge regions first need to be straightened to form a straight and flat welding surface. After welding the edges together, the hoop must be rounded again. The straight and flat regions are re-rounded to form an approximately round hoop. Next, the hoop is provided with flared ends to prepare the hoop for flow forming by positioning a cone like mandrel in a side opening of the hoop for pressing the end flared outwards during which relatively large shear forces occur. During the flow forming step, as e.g.

described in International patent application WO 2006/014110 of the applicant, the hoop is axially stretched and radially thinned. A relatively round hoop with flared ends increases the efficiency and effectivity of the flow forming step. A drawback of re-rounding the hoop is that the hoop may not become really round, but a flattened region in the hoop remains. Also during flaring, the flattened region remains. This decreases the efficiency and effectivity of the flow forming of the hoop.

An object of the invention is to provide a device that obviates at least one of the above mentioned draw backs.

Thereto, the invention provides a device for forming a flared hoop comprising an expandable mandrel comprising a cylindrical body with at least one flared end, wherein the mandrel is adjustable between a first position in which the mandrel has a diameter and a second position in which the mandrel has a larger diameter, wherein the device is arranged for positioning the mandrel in the first position in a hoop to be flared and for bringing the mandrel from the first position to the second position to provide the hoop with at least one flared end.

By providing an expandable mandrel that is adjustable between a first position with a certain diameter and a second position with a larger diameter, the hoop can be rounded and flared in one step. So, in the processing of a hoop until a rim one step, i.e. the step of rounding the hoop, can be omitted, thereby increasing the passage time of the hoop until a rim is formed.

By providing a mandrel comprising a cylindrical body and at least one flared end that is expandable between a first position having a certain diameter and a second position having a larger diameter, not only the flared ends but also the cylindrical body of the hoop is re-rounded by the mandrel.

In the first position of the mandrel, the mandrel can be positioned approximately entirely in the hoop. The mandrel may be approximately entirely received in the hoop. Then the mandrel is expanded from the first position to the second position, this is a relatively large expansion step during which the diameter of the mandrel increases and the mandrel forms a flared end on the hoop and re-rounds the cylindrical body of the hoop.

The mandrel can be provided as a cylindrical body having one flared end, or as a cylindrical body having two flared ends. Preferably, the hoop is provided with two flared ends, so a mandrel having two flared ends can flare the hoop at once. Preferably, the mandrel with two flared ends is

approximately as long as the hoop to be flared such that the mandrel can be received approximately entirely in the hoop. If a mandrel is used with one flared end, two mandrels may be needed, one for each end. Also one mandrel can be provided that is first used to flare one end of the hoop and secondly is used for flaring the opposite end of the hoop. By providing a mandrel with at least one flared end that can be approximately entirely received in the hoop to be flared, the device for flaring the hoop can become simpler.

Advantageously, at least the cylindrical body of the mandrel is provided as a perform. By providing the mandrel as a perform, a further step in the rim production process can be omitted, i.e. one flow rolling step can be omitted. So, less flow rolling steps are needed and the process time can further be reduced and the passage time can further be increased.

By providing the mandrel with wedge like parts, a relatively easy adjustment between the first position and the second position may be obtained. In the first position the wedge like parts may approximately abut against each other, the mandrel having a certain diameter. In the first position, the wedge like parts approximately abut each other, implying that a small gap may be present between the wedge like parts. In the second position a significant gap is provided between adjacent wedge like parts, such that the mandrel has in the second position an outer diameter that is larger than the outer diameter in the first position. If a small gap is present in the first position, the gap between the wedge like parts in the second position is significantly larger. The mandrel has in fact widened.

By adjusting the mandrel with the wedge like parts from the first position to the second position by placing a pin approximately centrally in the mandrel for opening the gaps between the wedge like parts, the mandrel can be easily and reliably adjusted from the first position to the second position. The pin usually is tapered, beginning with a relatively small diameter corresponding with the first position of the mandrel and ending with a relatively large diameter corresponding with the second position of the mandrel. By gradually entering the tapered pin in the mandrel, the mandrel is forced to open gradually until the second position is reached wherein a gap is provided between adjacent wedge like parts. By removing the pin from the mandrel, the mandrel can be adjusted from the second position to the first position wherein the outer diameter of the mandrel is smaller than in the second position. When the mandrel is in the first position again, it can be removed from the flared hoop. The flared hoop can then be processed further e.g. in a rim manufacturing street.

By providing crack detection means comprising providing the surface of a wedge like part with a pressurized air outlet in a portion forming part of the flared end of the cylindrical body and providing a duct running from a side portion of the wedge like part to the pressurized air outlet, crack detection of the hoop can be performed after a hoop has been rounded and flared, in particular leak detection of the weld can be performed. The weld applied when abutting edges of the coiled plate were welded together to form the hoop may have cracked, e.g. under influence of the expanding and flaring operation by the mandrel or the welding was insufficient. Crack detection is performed by injecting air, or other fluid, under pressure into the duct. An air pressure builds up due to the air flow. If the pressure drops, a significant leakage of air occurs, the hoop is likely to have a crack and is to be rejected for further processing into a rim. If no leakage of air occurs the flared hoop can be approved for further processing.

By providing the pressurized air outlet as an elongate chamber extending over a section of a width of the wedge like part, whereby the width of the wedge like part extends along a part of the circumference of the mandrel in rotational direction, positioning of the mandrel in a hoop to be flared does not require exact alignment of the weld and the pressurized air outlet. Hence, a slight deviation in the alignment of the weld and the pressurized air outlet is allowable.

The invention further relates to a method for forming a flared hoop comprising positioning the mandrel in the first position in a hoop to be flared; adjusting the mandrel from the first position to the second position to provide the hoop with at least one flared end and adjusting the mandrel from the second position to the first position to remove the flared hoop from the mandrel. By applying the method, in one step the hoop can be approximately rounded by the mandrel in the second position and can be provided with a flared end. The flared hoop can thus be relatively simply and reliable be prepared for the next processing step in a rim manufacturing street, such as flow forming.

By performing crack detection prior to adjusting the mandrel from the second position to the first position, no separate machine is necessary for supplementary checking whether the flared hoop is apt to be further processed into a rim.

By providing the cylindrical body of the mandrel with a preform, the shape of the flared hoop can be arranged such that during further processing less manufacturing steps are necessary.

The invention further relates to a hoop obtainable by the method. The invention also relates to a mandrel for forming a hoop with a flared end.

Further advantageous embodiments are represented in the subclaims.

The invention will further be elucidated on the basis of exemplary embodiments which are represented in a drawing. The exemplary

embodiments are given by way of non-limitative illustration of the invention.

In the drawing:

Fig. 1 shows a schematic perspective view of a device according to the invention wherein the mandrel is in the first position;

Fig. 2 shows a schematic perspective view of the device of Fig. 1 wherein the mandrel is in the second position;

Fig. 3 shows a schematic perspective view of a wedge like part of the device of Fig. 1; and

Fig. 4 shows another example of a wedge like part for the device of

Fig. 1. It is noted that the figures are only schematic representations of embodiments of the invention that are given by way of non-limiting example. In the figures, the same or corresponding parts are designated with the same reference numerals.

Fig. 1 shows a device 1 for forming a flared hoop. The hoop is not shown. The device 1 comprises an expandable mandrel 2 having a cylindrical body 3 and, in this embodiment, two flared ends 4. The mandrel 2 is adjustable between a first position, shown in Fig. 1, and a second position, shown in Fig. 2. The outer diameter of the mandrel 2 in the second position is larger than the outer diameter of the mandrel 2 in the first position. The mandrel 2 comprises here wedge like parts 5 that approximately abut each other in the first position. In the second position a relatively large gap 6 is provided between adjacent wedge like parts 5.

The mandrel 2 can be adjusted from the first to the second position by the pin 7. In this embodiment, the pin 7 is tapered, having a smaller diameter at the begin 7a than at the end 7b. The pin 7 is approximately centrally gradually entered into the mandrel 2 thereby enlarging the outer diameter from the mandrel 2. The mandrel 2 can be provided approximately centrally with an opening 8. In the opening 8 of the mandrel 2, the pin 7 may be received and may be further protruded in the mandrel 2.

The device 1 is further provided with a stop means 9 against which the hoop to be flared may abut. The stop means 9 are here provided as a flange at one end of the mandrel 2. The mandrel 2 can be approximately entirely received in the hoop to be flared until the hoop abuts against the flange 9. In the first position the outer diameter of the mandrel 2, inclusive of the flared ends 4, is smaller than the inner diameter of the hoop to be flared. Since the hoop may only be accessed from one side by the mandrel 2, the device 1 for forming the flared ends on the hoop and for rerounding the hoop may be relatively simple. The mandrel 2 can be expanded from the first position to the second position by protrusion of the pin 7 into the mandrel 2. The wedge like parts 5 of the mandrel 2 widen and gaps between the wedge like parts 5 become larger until the pin 7 approximately maximally protruded in the mandrel 2 and the mandrel 2 is in the second position. A relatively large stroke from the first position to the second position has been made. In the second position the cylindrical body 3, as well as the flared ends 4 of the mandrel 2 are in contact with the hoop to be flared. In the second position of the mandrel 2, the hoop is provided with flared ends corresponding with the flared ends 4 of the mandrel 2 and the hoop is approximately rounded again, corresponding with the outer diameter of the cylindrical body 3.

When the mandrel 2 is in the second position, the pin 7 may be removed from the mandrel 2 and the mandrel 2 may close again, the gaps 6 between the adjacent wedge like parts 5 become smaller until the wedge like parts 5 approximately abut against each other or only a limited gap between the wedge like parts 5 is present and the mandrel 2 is in the first position again.

In Fig. 3 a wedge like part 5 is shown in detail. Herein, the surface of the wedge like part 5 shows crack detection means comprising a pressurized air outlet 10 in a portion forming a part of one of the flared ends 4 of the cylindrical body 3. The pressurized air outlet 10 extends over a section of the width of the wedge like part 5. When part of a mandrel, the width of the wedge like part is to extend along a part of the circumference of the mandrel in rotational direction. The wedge like part 5 is further provided with a duct 11 running from a side portion of the wedge like part 5 to the pressurized air outlet 10. Consequently, the pressurized air outlet 10 and the duct 11 are in open connection with each other. In this embodiment, the pressurized air outlet 10 is provided as an elongate chamber extending over a section of the width of the wedge like part 5, but it may also be embodied as a slit or groove or other suitable shape. Pressurized air can be used, but also other fluids may be used, such as liquid or CO2 or otherwise.

The process for forming a flared hoop starts by positioning the mandrel in the first position in a hoop to be flared. Followed by adjusting the mandrel from the first position to the second position to provide the hoop with at least one flared end, resulting in a flared hoop. Once flared, adjusting the mandrel from the second position to the first position allows to remove the flared hoop from the mandrel.

Performing crack detection after adjusting the mandrel from the first position to the second position, but prior to adjusting the mandrel from the second position to the first position, allows checking whether the weld applied when abutting edges of the coiled plate were welded together to form the hoop may be cracked. For example, the weld may have cracked under influence of the rounding and flaring operation by the mandrel or welding was not adequately performed. Crack detection is performed by injecting air or other fluid under pressure into the duct. If a significant drop in pressure occurs, the hoop may have a crack and is to be rejected for further processing into a rim. If approximately no pressure drop occurs the flared hoop can be approved for further processing. When a hoop is taken from the machine that welds the abutting edges of the coiled plate, the position of the weld is known. Subsequently, the hoop may be gripped and positioned on the mandrel at the start of the flaring process such that the weld is aligned with the pressurized air outlet 10 of the wedge like part 5. Accordingly, crack detection can be performed in a single step without having to locate the weld and reposition the hoop. When a weld has cracked it usually runs from a side edge of the rim, therefore it suffices to check the weld near the side edge of the rim. Not precisely at the edge, but slightly away thereof as otherwise a false positive leakage may be detected when no crack is present. Also, it may be sufficient to provide a single wedge-like part with the crack detection means, since the location of the weld may be relatively well predictable when using the above mentioned mandrel. When using the above mentioned mandrel for flaring the hoop, the hoop is positioned over the mandrel, so the position of the weld can be predicted and can be approximately known.

Fig. 4 shows another example of a wedge like part 105 for the device 1 for forming a flared hoop. In this example, in addition to the flared ends 104, the cylindrical body of the mandrel further comprises a preform. This is achieved by providing the surface portion 103 of the wedge like part 105, forming part of the cylindrical body of the mandrel, with a preform portion 112, in this case an indentation. In this manner, the cylindrical body of the wedge like part 105 is shaped to define a preform surface. When the mandrel 2 of the device 1 is equipped with such wedge like parts 105, expanding the mandrel 2 from the first position to the second position provides a hoop with flared ends and in addition thereto with a preformed portion. The preformed hoop obtained in this manner provides additional advantages when it is processed further. In particular, the number of further processing steps may be reduced, and more specifically, the number of rim rolling steps may be reduced. In this example, the indentation of preform 112 allows the process of rim rolling to be executed with less manufacturing steps, as the flared hoop manufactured with such a mandrel provides a preformed shape which can more readily be rim rolled into a well of a rim. Consequently, the shape of the flared hoop already approximates more closely a shape preceding the shape of the rim to be produced. Also, such a mandrel with preform may be provided with crack detection means.

Many variants will be apparent to the person skilled in the art. Additionally to or alternatively of a pin, a hydraulic cylinder may be used for expanding the mandrel from the first position to the second position. Also other variants and/or embodiments of the crack detection means may be possible. All variants are understood to be comprised within the scope of the invention as defined in the following claims.

Claims

1. Device for forming a flared hoop comprising an expandable mandrel comprising a cylindrical body with at least one flared end, wherein the mandrel is adjustable between a first position in which the mandrel has a diameter and a second position in which the mandrel has a larger diameter, wherein the device is arranged for positioning the mandrel in the first position in a hoop to be flared and for bringing the mandrel from the first position to the second position to provide the hoop with at least one flared end.

2. Device according to claim 1, wherein at least the cylindrical body of the mandrel further comprises a preform.

3. Device according to claim 1 or 2, wherein the mandrel comprises wedge-like parts, wherein in the first position adjacent wedge-like parts are approximately abutting against each other and in the second position a gap is provided between adjacent wedge-like parts.

4. Device according to claim 3, wherein the device is arranged for adjusting the mandrel between the first position and the second position by placing a pin approximately centrally in the mandrel for opening the gaps between the wedge-like parts.

5. Device according to claim 3 or 4, wherein a wedge like part comprises a crack detection means.

6. Device according to claim 5, wherein the crack detection means comprise a pressurized air outlet in a portion forming a part of the at least one flared end of the cylindrical body; and a duct running from a side portion of the wedge like part to the pressurized air outlet.

7. Device according to claim 6, wherein the pressurized air outlet is an elongate chamber extending over a section of a width of the wedge like part.

8. Method for forming a flared hoop using a device according to any of the claims 1 - 7, comprising - positioning the mandrel in the first position in a hoop to be flared;

- adjusting the mandrel from the first position to the second position to provide the hoop with at least one flared end;

- adjusting the mandrel from the second position to the first position to remove the flared hoop from the mandrel.

9. Method according to claim 7, further comprising: performing crack detection prior to adjusting the mandrel from the second position to the first position.

10. Hoop with at least one flared end obtainable by the method according to claim 8 or 9.

11. Mandrel for forming at least one flared end on a hoop, wherein the mandrel comprises a cylindrical body with at least one flared end and the mandrel is adjustable between a first position having a diameter and a second position having a larger diameter.

12. Mandrel according to claim 10, wherein the cylindrical body of the mandrel further comprises a preform.

13. Mandrel according to claim 11 or 12, wherein the mandrel comprises wedge-like parts, wherein in the first position adjacent wedge-like parts are approximately abutting against each other and in the second position a gap is provided between adjacent wedge-like parts.

14. Mandrel according to claim 13, wherein at least one wedge like part comprises a pressurized air outlet in a portion forming a part of the at least one flared end of the cylindrical body; and a duct running from a side portion of the wedge like part to the pressurized air outlet.