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1. (WO2018228959) DISPENSER FOR WHEEL BALANCING WEIGHTS
Anmerkung: Text basiert auf automatischer optischer Zeichenerkennung (OCR). Verwenden Sie bitte aus rechtlichen Gründen die PDF-Version.
Dispenser for Wheel Balancing Weights

Field of the invention

The invention relates to an automatic dispenser for balancing weights, preferably self- adhesive balancing weights. Such balancing weights may be used for balancing wheels of vehicles.

Description of the related art

For balancing vehicle wheels, balancing weights are used. Self-adhesive balancing weights comprise segments of a mass material which may be a metal, like zinc or steel, having a self-adhesive tape at one side, by which the mass material may be held to a rim of a wheel. Multiple pieces or segments of such a mass material are held together by a strip of adhesive tape, forming a chain or a belt of balancing weights. The self-adhesive tape is protected by a liner, also called backing, at the side opposite to the balancing weight segments. Before applying a balancing weight to a rim, the liner is removed.

US 3,960,409 shows such a belt of balancing weights which may have a significant length and which may be wound up to a coil to simplify storage.

EP 1 128 176 A2 discloses a balancing weight having a plurality of weight ele-ments being fully enclosed by a strip-like surface layer. The surface layer has partial cuts between adjacent weight elements which extend from opposite lateral edges thereof in order to ease separation of a weight segment comprising one or more weight elements.

EP 3 040 578 Al discloses a dispenser for balancing weights with a transport section for transporting a belt of balancing weights segments and a cutting section for separating the belt of balancing weight segments into individual balancing weights.

EP 1 253 414 A2 discloses a complex dispensing device for balancing weights.

Here, the liner is removed from the self-adhesive tape, then sections of balancing weight are cut from the tape and directly fed to an applicator. This device is intended for automatic tire balancing systems.

In tire workshops, the mass required for balancing a wheel is determined by a balancing machine, and a corresponding number of balancing weight segments is manually cut off from a belt of balancing weights. Then the liner is removed and the balancing weight is applied to a rim. Manually counting the number of required balancing weight segments and cutting them off is time-consuming and prone to errors. To allow for manual handling, the balancing weight segments must have a minimum size which may be 10 or 5 grams. Lower masses would be difficult to handle, due to small size of the weight segments. This leads to a limited weight resolution and therefore to a limited balancing precision.

EP 3 040 578 discloses an automatic dispenser for balancing weights. A belt of balancing weight segments on a self-adhesive tape is moved by a driving belt to a cutting edge. After a selected number of balancing weight segments has passed the cutting edge, a counter holder is pressed on the cutting edge to form a 90 degree angle between two balancing weight segments. Then, a cutting knife is moved through the cutting edge and under the counter holder to cut the tape and to separate the selected number of balancing weight segments from the belt.

In automated systems a robot places the balancing weights to the rim. This robot can precisely determine the position of the balancing weights at the rim. When balancing weights are applied manually, the person applying the balancing weight must estimate the correct position of the balancing weight, as the balancing machine normally only indicates where to position the center of the balancing weight. If the center of the balancing weight does not fit to the indicated cen-ter position, there is a misbalancing of the wheel.

Summary of the invention

The problem to be solved by the invention is to provide a balancing weight, a dispenser for balancing weights and a method for marking balancing weights which allow precise positioning of a self-adhesive balancing weight at a wheel.

Solutions of the problem are described in the independent claims. The dependent claims relate to further improvements of the invention.

In a preferred embodiment, a dispenser for balancing weights comprises a transport section and a cutting section. The dispenser uses a belt of balancing weights comprising a plurality of balancing weight segments which are held together by a self-adhesive tape which may further be backed by a liner.

The transport section is for transporting the belt of balancing weights to provide a desired amount or number of balancing weight segments which are cut off the belt by the cutting section. The cutting section comprises at least one knife or cutter which is moved in a direction at right angle to the length of the belt of balancing weights. The knife is moved between adjacent balancing weight segments to cut the self-adhesive tape for separating the balancing weight segments. Preferably, further tape layers, like the liner are cut at the same time.

The dispenser provides a center mark at the balancing weight sections by making a partial cut in the self-adhesive tape and/or liner at the center or close to the center of the balancing weight section. The position of the partial cut is the gap between adjacent balancing weights closest to the center of the balancing weight section. The center of such a section is between adjacent weight segments, if there is an even number of weight segments. In the case of an odd number, the closest position to the center between two adjacent weight segments is selected. Alternatively, there may be two partial cuts at both sides of the center segment. In general, there may be 2 or more partial cuts indicating a center or a positioning range. The depth of the partial cut is selected such, that it is clearly visible, but the segments should not separate from each other. Prefera-bly, the depth of the partial cut is between 10% and 80%, more preferably between 20% and 50% of the width of the self-adhesive tape. The section may be bent to better identify the partial cut.

There may be cases, in which there are multiple cuts in the self-adhesive tape, for example to simplify bending. In such cases, the partial cut is preferably shaped different from the multiple cuts for sake of identification. For instance, the partial cut may then have a larger depth and/or a larger width than the multiple cuts.

It should be understood, that very short balancing weights having up to three balancing weight segments and, consequently, up to two gaps between adjacent balancing weight segments, may not at all have cuts with different shapes. The cuts rather may be identically partial. However, with these very short balancing wheels, on the one hand, a center mark is not really required for positioning, and, on the other hand, a robot or an experienced person will nevertheless recognize the partial cut as being different from the multiple cuts.

Alternatively or additionally, the partial cut may be positioned next to the multiple cuts with respect to a longitudinal direction of the belt of balancing weights, i.e. the partial cut does not coincide longitudinally with the multiple cuts. Such a non-coinciding partial cut may be narrower than the multiple cuts.

Another embodiment relates to a method of dispensing balancing weights by cutting balancing weight sections from a belt of balancing weights and providing a center mark formed by a partial cut as described above.

A further embodiment relates to a balancing weight or balancing weight section having a partial cut as described above.

The transport section may comprise at least one transport roller or belt for moving the belt by friction. To increase friction, there may be a counter roller or a counter belt for pressing the belt of balancing weights against the transport roller. A counter belt may be held and/or driven by a first pulley and a second pulley.

To further increase friction, it is preferred, that the transport roller or belt has a plurality of teeth preferably at its outer circumferential surface. Preferably these teeth have a diameter and a length, such that they intrude through the liner into the adhesive tape. Most preferably, the teeth do not touch and/or damage the balancing weight segments. Experiments have shown, that this may generate enough friction to precisely pull upwards a long belt from a stock being at a significantly lower level than the drive section. The mass of balancing weights which have to be lifted from the stock may be of several kilograms. The teeth always allow a precise transport even with minimal slipping back of the belt. A precise transport is desired for quick and precise cutting at the cutting section as the cutting knife has to precisely fit into the gap between adjacent weight segments. Another advantage of the teeth is the perforation of the liner with small holes re-ducing adhesion of the liner which significantly simplifies removal of the liner before applying the balancing weight to a rim.

To improve the contact of the belt of balancing weights with the transport roller or belt, and therefore to provide a good friction for transporting the belt of balancing weights, it is preferred, that the counter belt and/or the counter roller is pressed against the transport roller, which preferably may be done by a ten-sioner at the belt or at one or both of the pulleys.

It is further preferred to press the belt of balancing weights against the second transport roller by at least a second counter roller, which may be spring-loaded.

Preferably, the transport roller is driven by a motor, most preferably by a stepper motor. There may be a gear between the motor and the roller. A worm gear may be preferred, as this may block the belt from moving backwards due to the weight of the balancing weights between the stock and the drive section, when there is no power at the motor.

Preferably, the belt of balancing weight segments comprises a plurality of balancing weight segments which are held together by an adhesive tape for attaching the balancing weight segments to a rim of a wheel. A plurality of balancing weight segments may also be held together by an additional carrier like a plastic or metal tape or rod. The weight segments preferably comprise a mass material which may be a metal like zinc, lead, steel, tungsten, aluminum, tin or any other suitable material which may be a plastic material or any combination thereof.

It is further preferred if there is a backing or liner to protect the adhesive surface of the adhesive tape opposing to the balancing weights.

It is further preferred, that the adhesive tape has at least one strengthening layer to increase the shear strength of the belt to simplify transport by the transport section.

Preferably, the belt of balancing weights is wound to a coil which is supplied to the transport section.

It is preferred, that the transport section pulls the balancing weights at the belt of balancing weights from a stock which may be a coil of balancing weights, and it pushes the balancing weights into the cutting section. It is preferred to have at least one slideway which may be part of the cutting section on which the balanc-ing weights may slide horizontally.

It is further preferred, if the transport section forms an angle, which preferably is in the range between 70 and 110 degrees, and most preferably is a 90 degrees angle. It preferably receives balancing weights in a vertical direction, further redirecting the balancing weights to a horizontal direction. This may be done by curv-ing the belt of balancing weights at least partially around a transport roller. Although the horizontal and vertical directions disclosed herein are preferred, the embodiments may be arranged in any other way.

For transporting a desired number of balancing weight segments, either the length of transported belt may be measured, or the number of balancing weight segments may be counted. Both methods may be used together to get an additional reference and to increase reliability. For determining the length of transported balancing weight belt, it is preferred to have a slot wheel having a plurality of slots which may be detected and/or counted by means of a photo sensor. The slot wheel preferably is connected to the transport roller, but may also be connected to any other roller or belt. Instead of a slot wheel, there may be any other means for detecting rotation, like a resolver or angle encoder. There may also be a drive motor driving at least one of the wheels, most preferably the second transport roller, which preferably has an angle encoder or which may be a stepper motor. In the case of a stepper motor, the number of steps is a measure of the transported length of balancing weights.

Alternatively or additionally, there may be at least one means for counting the number of balancing weight segments. This may be done by detecting the gaps

between the balancing weight segments, for example by means of a photo sensor or any optical sensor. To increase the width of the gap, it is preferred to bend the belt of balancing weights. It is preferred to bend the belt of balancing weights around the transport roller, counting the balancing weights passing said first counter roller.

It is preferred, that the cutting section comprises a belt guide, against which the belt of balancing weights is pushed by the transport section. The belt guide is preferably arc shaped and forms a curve to bend the belt of balancing weights in a direction, such that the gap between adjacent balancing weight segments in-creases and a cutter can pass between said adjacent balancing weight segments to cut the belt into sections, preferably by cutting the adhesive tape and/or liner. The belt guide performs a continuous forming of the belt which is much quicker and less time-consuming than moving a counter holder on the belt to form the belt. Due to the continuous movement of the belt at the belt guide and lack of any pressing force to the belt, the probability of damaging like scratching the surface of balancing weight segments is much smaller.

Preferably, the belt guide is arc shaped. It may have an inner contour of an arc segment which may guide the balancing weight segments. The radius of the arc segment may be in a range between 2 times and 20 times, preferably, between 5 and 10 times the thickness and/or length of a balancing weight segment. The angle of the arc segment preferably is in a range between 30° and 150°, most preferably 90°. Preferably, the arc is shaped such, that the belt transported in a horizontal plane is deflected downwards. Here, bending of the belt is supported by gravity.

The cutter preferably should easily pass between adjacent balancing weights to be separated. This allows to use less cutting force and avoids damage of the sur- face of the balancing weight segments. The cut sides of the balancing weight segments are outer sides which are later visible when applied to a wheel. Therefore, there should not be any scratches or other markings.

Preferably, the cutter has a knife guide holding a knife and being configured to move from one side of the belt of balancing weights to the other side. The knife may be guided between two balancing weight sections. Preferably, the knife is only able to cut the adhesive tape (including backing or liner) connecting the balancing weight sections. It is not designed for cutting the material of balancing weight sections, which may be steel or aluminum, or any other metal.

To avoid a blockage of the dispenser and/or damaging of the knife, it is preferred to have a position sensor for detecting gaps between adjacent balancing weights. Preferably, the position sensor is over or near the position of the knife and/or the cutting path of the knife, such that it may detect the gap which is used by the knife for cutting. The position sensor may also be at least one balancing weight width distant from the knife position. If it is too far away, there may be changing distances between the detected position and an open gap due to mechanical tolerances and or stretching of the belt. The position sensor preferably is an optical sensor, but may be a magnetic sensor, an inductive sensor or any other sensor suitable for detecting a balancing weight segment and/or a gap between balancing weight segments.

For dispensing certain mass of balancing weights, first the required number of balancing weight segments may be calculated, unless this is already known. Further, the motor may be operated for a certain time, for a certain number of steps in the case of a stepper motor to push the required number of balancing weight segments towards the belt guide. Preferably, the motion of the motor is stopped, after the required number of balancing weight segments have passed and the position sensor has detected a gap. Then, preferably the knife is operated to move through the gap and to separate the required number of balancing weight segments from the belt.

Bending the belt by the belt guide further reduces stress to the adhesive tape. If the balancing weight segments would simply be pushed apart to produce a gap between two balancing weight segments, the comparatively flexible self-adhesive tape or foam would expand in length, while the less flexible backing or liner would tear or at least separate from the tape. This is prevented by the bending as disclosed above. For manually handling the cut balancing weight segments it is essential, that the liner remains in place. Otherwise, the cut segments would im-mediately stick to a tray into which the dispenser delivers the cut segments.

After a certain number of balancing weight segments have been cut by the cutter, they may slide and/or fall along the preferably vertical side of the cutter base driven by gravity and fall into a tray, from which they may be taken out and attached to a rim of a wheel.

The cutting section and the transport section preferably are used together as described herein. Alternatively, it is preferred to use the cutting section without or with a different transport section. For example, the transport section may be simplified and use only a first transport roller and a first counter roller to generate the required friction to the belt of balancing weights.

The embodiments described herein allow for automatic cutting of required mass sections form a belt of balancing weights. Due to the automatic transport and cutting a high speed can be achieved and a large number of balancing weight can be processed in a short time interval. Furthermore standard size segments of balancing weights as well as smaller and even significantly smaller segments can be processed. This may result in a much better balancing mass resolution compared to manual processing. Conventional balancing weight segments often are de-

signed to have a size which can easily be handled. Therefore, lightweight segments may be comparatively thin, resulting in a larger surface, which can better be gripped or they may be made of a low density material resulting in a larger size. By the embodiments, the balancing weight segments may have very small sizes as there is no need to increase size for manual handling of every segment.

Due to the automated cutting, a more stable and robust adhesive tape may be used. It may even have a robust support layer included. While it may be impossible to make a manual clean cut for separating segments, the automated cutting with a guided knife and the balancing weights held in a predetermined position at the cutting edge will result in a precise cut. Furthermore, the size of the balancing weight segments may be reduced to sizes like 5g, 2g, lg or less. This increases resolution and therefore balancing precision. Such small sizes can only be handled by an automated dispenser as they are too small for manual handling.

A further embodiment relates to a method for delivery of cut sections of balanc-ing weights. The method comprises the steps of transporting a certain number of balancing weight segments being part of a belt of balancing weights to a belt guide, bending the balancing weights extending such that a gap opens between two adjacent balancing weight segments and moving a knife from one side of the belt of balancing weights to the other side of the belt of balancing weights, and therefore cutting a balancing weight from the belt of balancing weights.

Description of Drawings

In the following the invention will be described by way of example, without limitation of the general inventive concept, on examples of embodiment with refer-ence to the drawings.

Figure 1 shows a preferred embodiment of a balancing weight.

Figure 2 shows another embodiment of a balancing weight.

Figure 3 shows a preferred embodiment of a dispenser.

Figure 4 shows an alternative embodiment of a dispenser.

Figure 5 shows a transport roller in detail.

Figure 6 shows a sectional view of the slideway.

Figure 7 shows the cutter in an operational state.

Figure 8 shows the cutter in an idle state.

Figure 1 shows a first embodiment of a balancing weight 110 having an even number of weight segments 105. The upper portion of the figure shows the balancing weight 110 in a top view, while the lower portion shows the balancing weight 100 in a bottom view, such that the adhesive tape 101 can be seen. The dashed lines between the upper and lower portions indicate the positions of the balancing weight segments 105. A partial cut 111 is at the center of the balancing weight 110 between the adjacent balancing weight segments 105 closest to the center (the third weight from any side). This partial cut 111 identifies the center of the balancing weight 110. Here only a small balancing weight 110 is shown to demonstrate the basic concept. It is obvious, that the center indication is more useful at larger (longer) balancing weights.

Figure 2 shows another embodiment with a balancing weight 112 having an odd number of weight segments 105. A partial cut 113 is at a position close to the center of the balancing weight 112 between the adjacent balancing weight segments 105 closest to the center. In this embodiment, the partial cut 113 is between the second and the third balancing weight segment 105 from the left.

In Figure 3, a preferred embodiment of a dispenser is shown in a side view. The dispenser comprises a transport section 300 and a cutting section 200. A belt of balancing weights 100 is fed by a drive mechanism to a cutter 250, where desired portions of mass material are cut from the belt of balancing weights 100. In this embodiment, a belt of balancing weights 100 comprising of a plurality of individual balancing weight segments 105, is fed at the left side in a feeding direction 102 into the transport section 300 of the dispenser. There may be a coil (not shown) for supplying the balancing weights 110, 112. Preferably, a transport roller 340 is provided for transporting the belt of balancing weights 100 having balancing weight segments 105, which preferably are coming from an approximately vertical direction preferably into an approximately horizontal direction, for easier cutting. A counter belt 320, which preferably is suspended between a first pulley 310 and a second pulley 330, preferably presses the belt of balancing weights 100 against the transport roller 340, and therefore generates friction to the belt of balancing weights 100. Friction may further be increased by teeth 341, 342 at the transport roller 340. It is preferred, that at least the transport roller 340 is driven by a motor (not shown). To determine the precise amount of balancing weight mass material, which has been transported, an angle encoder or counter may be provided.

After passing the transport roller 340, the balancing weights 110, 112, 120 are pushed in an approximately horizontal direction, and are guided by a slideway 260. The slideway 260 has an end section 263 and preferably a curved section 262 closely before the end section 263. Cutting is preferably done by a knife 215 which passes close to the end section 263. Preferably, the knife is held by a knife holder 216 and may be locked to the knife holder by a counter holder 217.

Before cutting, the belt section of balancing weights 120 to be cut off of the belt of balancing wheels 100 is bent to an angle of 90° or less by pushing the belt of balancing wheels 100 against a curved belt guide 220. Bending may further be supported by the curved section 262 of the slideway 260.

The balancing weights 110, 112, 120 of the curved belt of balancing weights 100 form a gap 106 between adjacent balancing weights 110, 112, 120 which allows the knife 215 to slide between two adjacent balancing weights 110, 112, 120. After forming the angle, the cutter comprising a knife 215 is moved from one side 107 to the other side 108 through the belt of balancing weights 100, cutting the adhesive tape 101 between two balancing weight segments 105, without cutting the balancing weight segments 105 themselves, and therefore separating a balancing weight 120 from the belt of balancing weights 100.

To transport and/or position the belt of balancing wheels 100, such that the knife 215 exactly passes through a gap 106 between adjacent balancing weights 110, 112, 120, it is preferred to provide a position sensor 270 which may be held by a sensor holder 271. Preferably, the position sensor 270 is arranged such, that it detects the gap 106 to be used by the knife 215 or an adjacent gap 106. The position sensor 270 may be an optical or magnetic sensor.

After cutting, a balancing weight 120 slides or falls down along sidewall 261 in a delivery direction 103 as indicated by an arrow, and may be delivered to a tray from which either a robot or a person may take out the balancing weight 110, 112, 120 for applying it to a wheel.

Figure 4 shows an alternative embodiment, similar to the embodiment above. Here, instead of the counter belt 320 a counter roller 350 is provided.

Figure 5 shows a transport roller 340 in detail. The transport roller 340 preferably is driven via a driveshaft 343 and via an optional gearbox (not shown) by a motor (not shown). Preferably, the transport roller 340 has a cylindrical shape. Most preferably, it has a plurality of teeth 341, 342 or spikes at its outer circumference. These teeth 341, 342 penetrate into the adhesive tape 101 of the belt of balancing weights 100 and improve friction for precise transport of the belt of balancing weights 100. Preferably, there are multiple rows of teeth 341, 342 which may be displaced against each other.

Figure 6 shows a sectional view of the slideway 260. The slideway 260 may have at least one sidewall 261 to prevent the belt of balancing weights 100 from sliding of the slideway 260. At the top of the slideway 260 a belt of balancing weights 100 comprising multiple balancing weight segments 105 on an adhesive tape 101 may be pushed forward by the transport roller 340.

In Figure 7, the operational state of the cutter 250 comprising a knife holder 216 with an attached knife 215 is shown. This image is a sectional view from right side of Figure 1 to the cutter 250, where the counter holder 217 has been omit-ted. Due to bending the belt of balancing weights 100, a gap 106 is formed at the cutting edge 202, through which a knife 215, which is attached to a knife holder 216, is moved in a cutting direction 253 from a first side 107 of the belt of balancing weights 100 to the second side 108 to separate the balancing weight 120 from the belt of balancing weights 100.

In Figure 8, the cutter 250 is shown in an idle state, where the knife 215 is next to the belt of balancing weights 100.

List of reference numerals

100 belt of balancing weights

101 adhesive tape

102 feeding direction

103 delivery direction

105 balancing weight segment

106 gap between balancing weight segments

107 first side

108 second side

110 balancing weight with even number of segments

111 partial cut

112 balancing weight with odd number of segments

113 partial cut

120 cut balancing weight

200 cutting section

202 cutting edge

215 knife

216 knife holder

217 counter holder

220 belt guide

250 cutter

253 cutting direction

260 slideway

261 sidewall

262 curved section

263 end section

270 position sensor

271 sensor holder

300 transport section

first pulley counter belt second pulley transport roller tooth tooth counter roller