Feeding of material is often performed, in this context, in that a movable pair of tongs grips the end of the band and draws a required length of the band. One further pair of tongs may be provided in order to keep the band, that has been drawn forwards. The production rate is often in the interval 25-150 details per minute. The length, drawn forwards, depends on the length of stroke of the movable pair of tongs, that is limited by two stops. The precision of the transport length is very important for the detail to be manufactured. The precision shall be in th interval 0,1 to 0,01 mm in order to get good accordance of the details. The transport length varies depending on the form an size of the detail and may be adjusted with the aid of two stops. In known embodiments of devices of this type a first stop may be adjusted in that it is screwed inwardly or outwardly whilst the second stop is fixed at transport arm, belonging to the device. Setting is carried out by the aid of allowed gauge blocks, placed by the setter between the two stops.

Deviations from the desired transport length occur for several reasons. Influencing factors are wear at the stops and other variations of production factors during manufacture. Errors may occur when setting, partly because of the human factor, partly for example because of wear of the stops, that causes setting being carried out against inclined surfaces. When errors are observed, the machine must be stopped, errors sought an resetting be carried out, which means loss of time, delayed production and increased costs.

The present invention relates to a method and a device for setting of the transport length by which said drawbacks are substantially eliminated. By the invention safe setting with great precision is achieved. The desired transport length can be set exactly even if one of the stops shows deviations. It is also possible to post-adjust in a simple way the setting when deviations in excess of those allowed occur.

The method and the device according to the invention and embodiments of same have the characterising features, that are given in the patent claims.

The invention shall be disclosed more in detail in the following, reference being made to the example of embodiment shown in the enclosed figures.

Figure 1 shows, principally, a plant comprising the device according to the invention Figure 2 shows the device according to the invention installed in plant.

Figure 3 shows the device according to the invention.

Figures 4 and 5 show the device when setting.

The plant according to figure 1 is intended for feeding and working of band material, preferably metals of different kinds. The band 1 is fed in a direction 2 to the left in the figure from a roll 15 containing material for long operation period. The movement is achieved by a pair of movable grip tongs 16, that may move to and fro between two stops 7,8. The feeding from the roll may also comprise other devices of known kind for achieving an even feed and avoiding too high load at the tongs. The feeding of the band with the pair of tongs 16 occurs intermittently and between the feedings the band is kept by a fixed pair of tongs 17. Hereby working of the band is carried out in succeeding devices 18,19. Pressing, bending and punching are examples of working operations.

The function of the device is more clearly disclosed in figure 2. The movable pair of grip tongs 16 comprises a lower portion 3 and an upper portion 4, which are arranged mutually movable vertically. The grip tongs are also as a whole movable horizontally, whereas the stroke length in one movement corresponds to the material length fed, often of the magnitude 30-100 mm. The horizontal movement occurs between the stops 7,8, which make portions of the setting device. Between each feed movement the material band is kept by the fixed pair of tongs 17, the grip portions 5,6 of which are mutually moveable in vertical direction. The stops are fastened at support portions 9,10 whereas also the grip portions 16,17 are fastened at or fixed in relationship to the same support. In some embodiments only one stop makes a device according to the invention whilst the other stop is formed as a portion fixed at the support.

The movable pair of tongs 16 and the fixed pair of grip tongs 17 are acted upon by a driving means comprising a feed wheel 25 acting upon the movable pair of tongs 16 by a spring loaded shaft 26. one extra wheel 24 is mounted, able to set, at the feed wheel 25 and acts upon the upper plate 27 of the spring loaded fixed grip pair of tongs 17. by adjustment of the extra wheel 24 the time for open and shut of the pair of grip tongs 17 may be varied and thus the keeping time for the material band 1.

The device for the stops is shown more closely in figure 3. The deice comprises a housing 23 that is fixed in relationship to a holder 12 and a fixture 9 and thus in relationship to other portions of the device. The housing has a protruding panel 21 with a digital display 22 to show the setting. From the housing there protrudes a shaft 7 out through the holder 7 such that the shaft also will form a stop for the movable pair of grip tongs mentioned above. The shaft 7 may be locked in the holder by screws 14. to set the position of the shaft 7 and thus the stop position for the movement of the pair of grip tongs, the shaft may be displaced by turning of the set knob 13 and the fine set knob 20. The relative position of the shaft can be read at the display 22, showing the position with and accuracy of 0,001 mm. Set devices of this type may form one or both of the stops.

The function when setting the machine by the method and th device according to the invention will now be described, reference being made to figures 4 and 5. To set the desired transport length 28 the feed wheel is set in start position (zero position) according to marking at the wheel. By turning the set knob 13 and the fine set knob 20 the shaft 8 is displaced to the start position in contact with the lower portion 3 of the movable pair of grip tongs. Then, in the same way the movable shaft 7 is set into contact with the lower portion 3 of the pair of grip tongs, whereupon it is screwed back to the desired stroke length. The display 22 shows the set stroke and feeding length.