FIELD OF THE INVENTION

The present invention relates to a feed mechanism for pocketed spring strands and to a pocketed spring assembly machine comprising one or more such feed mechanisms.

BACKGROUND OF THE INVENTION

Mattresses, sofas or other bedding or seating furniture may be provided with innerspring units formed of pocketed springs. The pocketed springs may for example include a spring which is formed of a metallic wire coil and a pocket formed of a nonwoven fabric which encloses the spring. In typical innerspring units, the pocketed springs are provided in the form of strands which include multiple pocketed springs enclosed by pockets formed from the same fabric sheet(s). An innerspring unit may then be formed by joining multiple pocketed spring strands of to each other, e.g., by welding, gluing or the like. This is preferably accomplished in an automated manner, using a pocketed spring assembly machine which receives the multiple pocketed spring strands, aligns the pocketed spring strands, and joins the pocketed spring strands to form the innerspring unit. For this purpose, it is typically required that the pocketed spring strands are fed in a well-defined manner into the pocketed spring assembly machine.

Accordingly, there is a need for techniques which allow for efficiently and precisely feeding a pocketed spring strand into a pocketed spring assembly machine.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a feed mechanism and a pocketed spring assembly machine. The dependent claims define further embodiments.

Accordingly, an embodiment provides a feed mechanism for pocketed spring strands. The feed mechanism comprises an index wheel having a plurality of blades for engaging between pocketed springs of a pocketed spring strand. Further, the index wheel comprises a motor for driving rotation of the at least one index wheel. Accordingly, the pocketed spring strand can be conveyed by rotation of the index wheel, while at the same time ensuring precise positioning of the individual pocketed springs of the pocketed spring strand. The index wheel comprises a first support member which is rotatable about a first rotation axis. The first support member comprises, for each of the plurality of blades, a first support element which supports a shaft element of the blade to be tiltable about a tilt axis extending in parallel to the first rotation axis. Further, the index wheel comprises a second support member which is rotatable about a second rotation axis extending in parallel to the first rotation axis. The second support member comprises, for each of the plurality of blades, a second support element which is slidable along the shaft element and supports the shaft element of the blade to be tiltable the said tilt axis. The first support member and the second support member are movable relative to each other to set a parallel shift of the first rotation axis and the second rotation axis.

In the feed mechanism, the parallel shift of the first rotation axis and the second rotation axis can be used to efficiently set a spacing of the blades when engaging the pocketed spring strand. If the first rotation axis and the second rotation axis are aligned, the spacing of the blades may be defined by an angular spacing of the first support elements on the first support member and an angular spacing of the second support elements on the second support member. If the parallel shift is increased, for some of the blades the second support member will slide along the shaft element towards or away the first support member, at the same time tilting the shaft element about the tilt axis. For a given blade, this effect varies as the index wheel rotates. Accordingly, the spacing between two neighboring index wheels can be adjusted by varying the parallel shift of the first support member and the second support member. For example, this can be used to set the spacing between the neighboring blades to correspond to a diameter of the springs of the pocketed spring strand.

According to an embodiment, the index wheel may further comprise a Cardan joint mechanism coupling the first support member and the second support member. By means of the Cardan joint mechanism, it can be efficiently ensured that the first support member and the second support member rotate synchronously, while still allowing the above-mentioned setting of the parallel shift of the first rotation axis and the second rotation axis.

According to an embodiment, the index wheel comprises a sleeve which is arranged coaxially with one of the first rotation axis and the second rotation axis, receives a portion of the other of the first rotation axis and the second rotation axis, and limits the parallel shift of the first rotation axis and the second rotation axis. In this way, adjustment and movement of index wheel may be controlled in an efficient manner.

According to an embodiment, the sleeve accommodates the Cardan joint mechanism. In this way, the index wheel may be provided with a compact structure.

According to an embodiment, the first support elements are distributed with equal angular spacings around the first rotation axis and the second support elements are distributed with the same equal angular spacings around the second rotation axis. However, it is noted that other arrangements are possible as well. For example, by using a an angular spacing which varies over cycle around the first rotation axis and the second rotation axis, the spacing of the blades could be varied in accordance with different spring diameters used in the pocketed spring strand.

According to an embodiment, the feed mechanism comprises a belt drive mechanism for coupling the motor to the index wheel. By using the belt drive mechanism, the coupling of the motor to the index wheel can be provided in an efficient manner while at the same time allowing shifting of the first rotation axis and/or the second rotation axis. Further, the belt drive mechanism may be used for efficiently driving rotation of multiple index wheels of the feed mechanism.

According to an embodiment, the feed mechanism comprises a further motor for moving the first support member and the second support member of the index wheel relative to each other to set the parallel shift of the first rotation axis and the second rotation axis. In this way, the parallel shift can be set precisely and in an automatically controlled manner.

As mentioned above, the feed mechanism may comprise multiple index wheels. These multiple index wheels may each have a configuration as described above. Accordingly, in an embodiment the feed mechanism comprises a further index wheel having a plurality of blades for engaging between the pocketed springs of the pocketed spring strand. The further index wheel comprises a third support member which is rotatable about a third rotation axis and comprises, for each of the plurality of blades of the further index wheel, a first support element which supports a shaft element of the blade to be tiltable about a tilt axis extending in parallel to the third rotation axis. Further, the further index wheel comprises a fourth support member which is rotatable about a fourth rotation axis extending in parallel to the third rotation axis and comprises, for each of the plurality of blades of the further index wheel, a second support element which is slidable along the shaft element of the blade and supports the shaft element to be tiltable about the tilt axis. The third support member and the fourth support member are movable with relative to each other to set a parallel shift of the third rotation axis and the fourth rotation axis. Accordingly, also the further index wheel may allow for adjusting the spacing of the blades when engaging the pocketed spring strand by setting the parallel shift of the third rotation axis and the fourth rotation axis.

According to an embodiment, rotation of the index wheel and rotation of the further index wheel are driven by the same motor. In this way, complexity of the feed mechanism may be reduced. Further, using the same motor to drive rotation of the index wheel and rotation of the further index wheel may facilitate providing synchronous rotation of the index wheel and the further index wheel.

According to an embodiment, the feed mechanism comprises a belt drive mechanism for coupling the motor to the index wheel and to the further index wheel. In this way, the coupling of the motor to the index wheel and the further index wheel can be provided in an efficient manner while at the same time allowing shifting of the first rotation axis, the second rotation axis, the third rotation axis, and/or the third rotation axis.

According to an embodiment, the index wheel and the further index wheel are arranged on opposite sides of the pocketed spring strand and rotation of the further index wheel is driven by the motor in a direction which is opposite to rotation of the first index wheel. Accordingly, the pocketed spring strand can be conveyed in a precisely controlled manner between the index wheel and the further index wheel.

According to an embodiment, the feed mechanism comprises a further motor for moving the first support member and the second support member relative to each other to set the parallel shift of the first rotation axis and the second rotation axis, and for moving the third support member and the fourth support member relative to each other to set the parallel shift of the third rotation axis and the fourth rotation axis. Accordingly, the same motor can be used for both index wheels to set the parallel shift precisely and in an automatically controlled manner.

According to an embodiment, the feed mechanism comprises a spindle drive coupling the further motor to the index wheel and the further index wheel. The spindle drive may be used for efficiently translating a rotational movement of the motor into the parallel shift. Furthermore, the spindle drive may be used to ensure that the setting of the parallel shift of the first rotation axis and the second rotation axis and the parallel shift of the third rotation axis and the fourth rotation axis occurs in a symmetric manner.

According to a further embodiment, a pocketed string assembly machine is provided. The pocketed spring assembly machine comprises at least one feed mechanism according to any one of the above embodiments.

