Specification

The present invention refers, in general, to a handling system for sewing machines. More specifically, it is a needle bar handling system for a sewing machine.

As is well known, on sewing machines there is a needle bar formed by a shaft and one or more needles, fixed to the lower end of the shaft.

To make the sewing, the needles must pass through the fabric to be sewn and, for this purpose, the needle bar must move in a vertical direction in an oscillating way.

To achieve this movement, the needle bar is connected to a crank which is in turn eccentrically pivoted to a cylindrical element mounted coaxially on a rotating pin.

Depending on the thickness of the fabric to be sewn, it is necessary to have a different length of needle bar stroke. In particular, if the fabric is thick, the stroke must be longer than that required for sewing a thinner fabric.

Consequently, before sewing a new fabric with a different thickness than the one previously sewn, one or more changes must be made to the needle bar handling system and/or the needle bar itself. In particular, these modifications can be

- the replacement of the needle bar shaft with a shorter or longer shaft;

- the replacement of the crank handle with a shorter or longer one;

- the replacement of the cylindrical element on which the crank is pivoted so as to modify the distance between the axis of rotation of the rotating pin and the point of connection of the crank with the cylindrical element. The time to be dedicated to these modifications can be significant and can significantly reduce the efficiency of the entire sewing machine, even if you choose to make only one replacement among those listed above.

There are also well-known needle bar handling systems that make it easier to set the needle bar itself, such as those disclosed in the CN 109 972 308 A and JP H07 51480 A patent documents.

The purpose of this invention is to offer a needle bar handling system for a sewing machine, namely a handling system that can be easily adapted according to the thickness of the fabric to be sewn. Another purpose of the invention is to significantly reduce the setting time of the needle bar stroke of a sewing machine to vary the thickness of the fabric to be sewn or for other needs.

Another purpose of the invention is to provide a handling system that is easy to manage. These and other purposes are achieved, according to the invention, by a needle bar handling system of a sewing machine including a needle bar with a vertical shaft to which a crank, in turn connected to a cylindrical element, is connected.

In particular, in the movement system according to the invention the crank is connected to the cylindrical element by means of an adjustment device, the crank being pivoted with a pin to the adjustment device.

According to this configuration the adjusting device can adjust the position of the pin with respect to the axis of rotation of the rotating shaft, so as to move the crank and vary the length of the needle bar stroke. The adjusting device comprises a fixed element permanently mounted on the cylindrical element, and a mobile element on which the crank is pivoted, the mobile element being fixable to the fixed element in variable positions.

In particular, the mobile element can be shifted with respect to the fixed element. Advantageously, the mobile element can be moved with respect to the fixed element in a radial direction with respect to the cylindrical element. In this way, the pivot through which the crank is pivoted to the moving element is always arranged on a radius of the cylindrical element.

At least one slotted hole can be made in the movable element, which develops in a radial direction with respect to the cylindrical element, the slotted hole being at least one that can be crossed by a screw that can be screwed into a threaded hole in the fixed element.

In addition, the fixed element can include two lateral shoulders between which the mobile element can move, so as to control the movement of the mobile element when adjusting its position with respect to the fixed element.

Further features and details can be better understood from the following description, given as a non-limiting example, as well as from the annexed drawing, wherein: figure 1 is an axonometric view of a movement system, according to the invention, of the needle bar of a sewing machine; figure 2 is a side view of the handling system in figure 1 .

With reference to the attached figures, figure 10 indicates a handling system of the needle bar of a sewing machine as a whole.

The handling system 10 includes a needle bar 12 including a vertical shaft 14 and three sewing needles 16 fixed below the vertical shaft 14. A crank handle 18 is connected to the vertical shaft 14, which in turn is pivoted to an adjustment device 20 by means of a pin 19.

The adjusting device 20 is fixed to a cylindrical element 22 mounted coaxially on a rotating shaft, not shown in the figures, but configured according to the known art.

The adjusting device 20 comprises a fixed element 24 and a movable element

26.

The fixed element 24 is permanently mounted on the cylindrical element 22 by means of two first screws 28 and includes two side shoulders 30.

The mobile element 26, which is received between the two side shoulders 30, is fixed to the fixed element 24 by means of two second screws 32 which pass through two slotted holes 34 in the mobile element 26.

Consequently, by loosening the two second screws 32, it is possible to move the mobile element 26 between the two side shoulders 30 of the fixed element 24 and modify the distance between the pin 19 and the center of the cylindrical element 22.

This adjustment is possible because the translation of the mobile element 26 with respect to the fixed element 24 takes place in a radial direction with respect to the cylindrical element 22.

In fact, the development of the slotted holes is in the radial direction with respect to the cylindrical element 22.

As this distance increases or decreases, the vertical shaft stroke 14 and therefore the entire needle bar 12 is increased or decreased respectively. The movement system 10 according to the invention allows, therefore, to vary the length of the needle bar stroke easily and quickly, so as to adjust the action of one or more needles on the fabric as its thickness changes.