Patent Description:
Some consumer items are transported protected by a special package. This type of packages is formed by plastic sheets comprising air pads or bubbles, according to the case.

In some cases, the package is general and is only modified in size in accordance with the size of the item to be packaged. In other cases, however, the packages are adapted to the size of the item that they are going to protect. In this latter case, furthermore, it is possible for the package to be formed by several parts to this be able to arrange it in different areas of the item to be protected.

In these latter cases, the package is of the type formed by pads. These packages are generally formed from two sheets which are joined or welded to one another both longitudinally and transversely, how and where required, forming independent sectors therebetween (as a result of the different welds). If necessary, it is possible to keep a communication between the sectors. During the manufacture of the packages, the sectors are filled with air selectively, being left empty or full of air in accordance with requirements. A sector full of air is what is known as pad.

<CIT>, of the same applicant, discloses an installation for manufacturing packages with pads. This installation comprises a plurality of longitudinal welding heads arranged in group, to be able to carry out different longitudinal welds between two superposed plastic sheets.

<CIT> also discloses an installation for manufacturing packages with pads, with a welding station comprising a welding head for carrying out longitudinal welds between two superposed sheets. The welding head comprises two sealing blocks between which the sheets are arranged to be welded or sealed to one another. The sealing blocks are hot and the sheets are welded by contact. This type of welds has the great drawback of the advance speed of the sheets being limited, mainly due to the need of contact of the sheets with the welding blocks, and of keeping said contact to heat the sheets.

<CIT> discloses an apparatus for inflating and sealing packing cushions has a drive mechanism for feeding a preconfigured film material to a sealing mechanism in a flattened state without wrinkles in the sealing region in which a longitudinal seal is formed. In one aspect, the drive mechanism comprises a pair of upper adjacent belts and a backing element. such as a lower belt. The sealing mechanism may be a rotary sealing wheel that contacts the film material between the upper adjacent belts.

<CIT> discloses an apparatus for side sealing packages made of plastic films and consists of a rotary member having a heated sealing and cutting blade to the side of which is another blade, heated by the first blade, the two blades forming a pair of seals. The blades bear against a moving belt which also supports the package, and a pair of upper belts are provided one to each side of the rotary member, these belts working in conjunction on the upper side of the seal to remove any tension thereon during and immediately after sealing.

<CIT> discloses a method and apparatus for forming a tamper resistant seal on a plastic bag containing a loaf of bread or other products. The neck of the bag is flattened, gripped between a pair of upper inboard and outboard gathering belts and a pair of lower inboard and outboard gathering belts adjacent opposite sides of a segment of the neck of the bag.

<CIT> discloses a bag closing machine with a pair of endless belt mounted in a housing and having adjacent runs extending along a passage in the housing. The belts are driven to cause bags to be conveyed successively between the runs along the passage. A heating station adjacent the passage is operable to heat sealing areas of the bags to activate heat sealable material in a bag closing manner.

The object of the invention is to provide a welding station comprising a plurality of longitudinal welding heads and an installation comprising a welding station, as defined in the claims A longitudinal welding head is adapted to join or weld to one another two superposed sheets as said sheets advance in a first direction. The head comprises a welding device configured to apply heat on a determined action area of the head to carry out said welding by heat.

The longitudinal welding head comprises a main body, a first traction belt wound to the main body and a second traction belt wound to the main body, parallel to the first traction belt and separated from the first traction belt by a determined separation gap in a second direction which is preferably transverse to the first direction. The main body comprises a first drive wheel with a first central shaft extending in the second direction, and a second drive wheel with a second central shaft extending parallel to the first central shaft and distant from said first central shaft in the first direction. Both traction belts are wound in both drive wheels of the main body.

The action area on which heat is applied is in the separation gap defined between both traction belts, such that the welding between the sheets can be carried out in parts of said sheets which move facing said separation gap, between both traction belts. Thus, in the head a sealed area can be delimited between both traction belts, it being possible to apply the welding to join both sheets to one another in a secure and efficient manner.

An aspect of the invention relates to a welding station comprising a plurality of longitudinal welding heads such as the one previously described, each of the welding heads being configured to be able to move along the second direction, and another aspect of the invention relates to an installation comprising at least one of said welding stations.

These and other advantages and features of the invention will become evident in view of the figures and of the detailed disclosure of the invention.

A longitudinal welding head <NUM> is adapted to be used in installations <NUM> in which packages with pads are manufactured. The head <NUM> is configured to act on two superposed sheets L advancing in a determined first direction A (the figures depict the assembly formed by the superposed sheets L), facing said head <NUM>, as shown in <FIG>, and to weld or join said sheets L to one another in areas of said sheets L on which said head <NUM> acts. To that end, the head <NUM> comprises a welding device, not depicted in the figures, configured to apply heat to a determined action area <NUM> of said head <NUM>, or facing said head <NUM>, such that when the sheets L pass through said action area <NUM>, the sheets are joined or welded to one another by heat. The first direction A is preferably linear, the head <NUM> thus being configured to carry out longitudinal welds on the sheets L as said sheets L advance linearly.

The head <NUM> comprises a first traction belt <NUM> and a second traction belt <NUM> arranged in parallel to the first traction belt <NUM> and separated from the first traction belt <NUM> by a determined separation gap D in a second direction T, which is preferably transverse to the first direction A.

The head <NUM> comprises a first drive wheel <NUM> with a first central shaft <NUM> extending in the second direction T, and a second drive wheel <NUM> with a second central shaft <NUM> extending parallel to the first central shaft <NUM> and distant from said first central shaft <NUM> in the first direction A. Both traction belts <NUM> and <NUM> are wound in both drive wheels <NUM> and <NUM>, as shown in <FIG>. The action area <NUM> is arranged in, or facing, said separation gap D. In this way, when the sheets L move, the areas of said sheets L which are in contact and/or facing said action area <NUM> are affected by said heat and are welded or joined to one another.

Alternatively, the head <NUM> can comprise a respective drive wheel for each traction belt <NUM> and <NUM> associated with each central shaft <NUM> and <NUM>.

The drive wheels <NUM> and <NUM> are configured to rotate with respect to their respective central shafts <NUM> and <NUM>, transmitting this rotation to the traction belts <NUM> and <NUM> which, in turn, aid the sheets L in moving in the first direction A (they pull the sheets L in said first direction A). The rotation of all drive wheels <NUM> and <NUM> is synchronized, and it is also synchronized with a traction device causing the movement of the sheets L in the first direction A, in the cases in which a traction device of this type is required. In some embodiments, one of the drive wheels <NUM> and <NUM> is motor-driven and the head <NUM> comprises means for transmitting the rotation of said drive wheel <NUM> or <NUM> to the other drive wheel <NUM> or <NUM>. In other embodiments, all the drive wheels <NUM> and <NUM> are motor-driven.

In some embodiments, the head <NUM> comprises a separating element <NUM> joined to each of the drive wheels <NUM> and <NUM>, the first traction belt <NUM> being on one side of said separating element <NUM> with respect to the corresponding central shaft <NUM> and the second traction belt <NUM> being on the other side of said separating element <NUM>. Said separating element <NUM> preferably comprises a width equal to the width of the separation gap D in the second direction T. The outer surface of the separating element <NUM> of the head <NUM> is preferably at the same level as the outer surface of the traction belts <NUM> and <NUM>. Thus, if the head <NUM> rests on a support (pressing, therefore, the sheets L against said support), a sealed area is generated between both traction belts <NUM> and <NUM> and both separating elements <NUM>, the action area <NUM> being in said sealed area. As a result of the sealed area, by moving the sheets L between said support and the head <NUM> in the first direction A, the welding between said sheets L can be carried out securely and in an environment isolated from the exterior (in the sealed area), such that most of the heat applied in the action area is furthermore taken advantage of to carry out the required welding, a more effective welding being achieved. This furthermore allows having a welding device of a power adapted to the requirements to be met in order to carry out the welding, without needing to size it in excess due to the possible heat losses.

To bear the traction belts <NUM> and <NUM> in the drive wheels <NUM> and <NUM>, said drive wheels <NUM> and <NUM> can comprise different configurations. In some embodiments of the head <NUM>, the drive wheels <NUM> and <NUM> comprise a respective groove configured to house each traction belt <NUM> and <NUM>, the two grooves of each drive wheel <NUM> and <NUM> being separated by a distance equal to the width of the separation gap D. In this case, the separating elements <NUM> could be dispensed with since the configuration of the grooves would fulfill the function of the separating elements <NUM>. In other embodiments of the head <NUM>, the drive wheels <NUM> and <NUM> are gear wheels and the traction belts <NUM> and <NUM> comprise a configuration complementary to the teeth of said drive wheels <NUM> and <NUM>. In these cases, the separating elements <NUM> could be dispensed with depending on the configuration of the drive wheels <NUM> and <NUM> and of the traction belts <NUM> and <NUM>, depending on whether or not this configuration allows the movement of the traction belts <NUM> and <NUM> (in which case the use of the separating elements <NUM> would be advantageous).

In some embodiments, such as the shown by way of example in <FIG>, the head <NUM> comprises a holding-down device <NUM> with at least one hold-down member <NUM> arranged downstream of the action area <NUM> in the first direction A and configured to press on the already welded sheets L. Thus, when the sheets L move in the first direction A on a support, the holding-down device <NUM> presses said sheets L against said support, keeping the previously made weld joined to assure to a greater extent that it is correctly completed until it as cooled down. Preferably, furthermore, the holding-down device <NUM> comprises a plurality of hold-down members <NUM> arranged in series in the first direction A, and said hold-down members <NUM> can exert the same force on the sheets L or can be configured such that the pressure force that can be applied by each of the hold-down members <NUM> can be controlled independently. The latter would allow adjusting the force for different types of sheets L or different speeds of movement of the sheets L in the first direction A, for example.

In some embodiments, the head <NUM> comprises a cooling device not depicted in the figures, to cool the sealed area which is generated in the separation gap D present between both traction belts <NUM> and <NUM>, downstream of the action area <NUM> in the first direction A. In the embodiments in which the head <NUM> comprises a holding-down device <NUM>, the cooling device is preferably configured to cool the area of the separation gap D downstream of said holding-down device <NUM> in the first direction A, and/or in the areas of the separation gap D in which the holding-down device <NUM> acts. Thus, the cooling of the sheets L after being welded is accelerated with the cooling device, the welding carried out being ensured to a greater extent since the risk of said welding being separated downstream of the head <NUM> in the first direction A for any reason is reduced.

The welding deice preferably comprises a laser emitter emitting a laser beam towards the action area <NUM>, directly or by means of additional elements (such as mirrors, for example) arranged between said welding device <NUM> and said action area <NUM> to redirect said laser beam towards said action area <NUM>. The welding device is preferably configured so that the heat reaches the action area vertically.

An aspect of the invention relates to a welding station <NUM> for an installation <NUM> for manufacturing packages with pads, comprising a plurality of longitudinal welding heads <NUM> such as the one previously described, in any of its configurations and/or embodiments.

In some embodiments, the welding station <NUM> comprises a support which is facing said head <NUM> and configured so that the sheets L move between it and the head <NUM> in the first direction A. The head <NUM> is facing the support such that the traction belts <NUM> and <NUM> press the sheets L against said support (but with a force allowing the movement of said sheets L in the first direction A), and cause or aid in the traction of said sheets L as has been previously described, the sealed area previously described being generated between said support and the head <NUM>. In these embodiments, the head <NUM> preferably comprises an actuator <NUM> which is arranged upstream of the action area <NUM> in the first direction A and configured to push the sheets L to be welded against the support, as depicted in <FIG>, such that it is ensured that said sheets L reach the action area <NUM> tensioned and that the welding can be carried out as effectively and securely as possible. Furthermore, the actuator <NUM> preferably comprises a pressure wheel <NUM> and the support comprises a depression complementary with the pressure wheel <NUM> (not depicted in the figures) and facing said pressure wheel <NUM>, to ensure to a greater extent the generation of the tension in the sheets L.

In other embodiments, the support is selected from:.

In any embodiment, the welding station <NUM> comprises a plurality of longitudinal welding heads <NUM>, each one, preferably, with a facing support, each of the welding heads <NUM> being configured to be able to move along the second direction T. This allows carrying out a plurality of longitudinal welds of the sheets L, parallel to one another, when the heads <NUM> are arranged in different positions along said second direction T. Each head <NUM> is preferably arranged in a determined position along the first direction A, said positions being different from one another (as can be seen in <FIG>). When the support is a support surface, the same support surface can be facing all the heads <NUM>, whereas when the support comprises a support head <NUM>, each head <NUM> has associated a support head <NUM>.

Claim 1:
Welding station (<NUM>) comprising a plurality of longitudinal welding heads (<NUM>) for an installation for manufacturing packages with pads, each head (<NUM>) being configured to weld to one another two superposed sheets (L) as said sheets (L) advance in a first direction (A), each head (<NUM>) comprising a welding device configured to apply heat on a determined action area (<NUM>) of said head (<NUM>) or facing said head (<NUM>), a first traction belt (<NUM>) and a second traction belt (<NUM>) parallel to the first traction belt (<NUM>) and separated from the first traction belt (<NUM>) by a determined separation gap (D) in a second direction (T) which is transverse to the first direction (A), the action area (<NUM>) being arranged in said separation gap (D) between both traction belts (<NUM>, <NUM>), or facing said separation gap (D), and each of the welding heads (<NUM>) being configured to be able to move along the second direction (T).