GB2046393A

GB2046393A - A machine provided with a finger protection guard device for a movable upper tool

Info

Publication number: GB2046393A
Application number: GB8009159A
Authority: GB
Original assignee: William Prym Werke GmbH and Co KG
Current assignee: William Prym Werke GmbH and Co KG
Priority date: 1979-04-14
Filing date: 1980-03-19
Publication date: 1980-11-12
Also published as: FR2454046A1; SE8002750L; DE2915328C2; FR2454046B1; JPH0156318B2; JPS55142188A; IT1141561B; IT8021294A0; SE442239B; GB2046393B; DE2915328A1; BE882746A

Abstract

A machine having an upper tool 12 which is movable towards a lower tool 13 by a rod 11 moved by an eccentric 29 provided on a drive shaft 26 driven by a motor 30, the upper tool 12 being provided with a finger protection guard device 15 arranged to be moved downwardly with a lead with respect to the upper tool 12 by a cam device 28 provided on the shaft 26, the means for moving the guard device 15 including two bars 17, 19 arranged parallel to each other and mounted parallel to the rod 11 by means of guide grooves 22, 23, 24, a guide pin 18, a mounting pin 25 fixed to the housing 4 and the shaft 26 and are held relative to each other by a tension spring 20 extending between the pins 18, 25, the bars 17, 19 carrying electrical contacts 31, 32 for controlling the operation of the motor 30. If an operator's finger lies in the path of the guard 15 the bars 17, 19 move relative to each other to open the contacts 31, 32 to stop the motor 30. <IMAGE>

Description

SPECIFICATION A machine provided with a finger protection guard device for a movable upper tool This invention relates to a machine provided with a finger protection guard device for a movable upper tool.

A machine is disclosed in German Specification DOS No. P.2556516, wherein there is a finger protection device which is in the form of a workpiece hold-down means which operates with a tongs-like action, which finger protection device controls the working machine drive with electrical control means which are arranged on link members which are force-lockingly connected together. It has been found that, because of the elbow lever-like configuration of the link members which carry the electrical control means, it is necessary for the main drive shaft to be arranged at a greater distance from the pressing thrust member, and therefore requires a comparatively large dimension in respect of depth of the working machine, which is particularly disadvantageous when the working machine is arranged on a free-standing support.

With the machine disclosed in the above mentioned patent specification, it has been found that, when working with thick padded workpieces, switching off of the machine drive can still occur after the safety distance has been covered.

According to the present invention there is provided a machine having an upper tool movable towards a lower tool by an eccentric driven by a main drive shaft, a finger protection guard device disposed around the upper tool and arranged to be moved downwardly with a lead with respect to the upper tool by a cam disc provided on the main drive shaft, the means for moving the finger protection guard device including two members which are force-lockingly connected together and which carry electrical switching means for controlling operation of a drive motor which drives the main drive shaft, said two members which carry the electrical switching means being in the form of bars which are arranged parallel to each other, said bars being mounted on the machine parallel to the pressing thrust member which moves the upper tool by means of guide grooves, a guide pin, a mounting pin fixed with respect to the machine housing, and by means of the main drive shaft and are held in contacting engagement with each other by means of a tension spring which is arranged between the pins.

The present invention combines together the drive means for the pressing thrust member and the drive means for the finger protection device, in such a way that the movable parts are arranged in the direct vicinity of the pressing thrust member and with the same kind of extent in respect of their control movements, including the means for locking the finger protection device at the safety distance.

The two link members which are arranged in the drive of the finger protection means, are provided, for controlling the drive motor of the machine, as straight link members which are movable parallel to each other and which are disposed substantially perpendicularly below the axis of the main drive shaft.

An embodiment of the invention will now be described, by way of an example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a machine which is equipped with protection means in accordance with the invention, Figure 2 shows a partly sectional front view of the operative part of the machine, Figure 3 shows a side view of the machine, in section through the drive of the finger protection device, in the raised position thereof, Figure 4 shows a side view similar to Figure 3, but in section through the drive of the upper tool, Figure 5 shows a view similar to Figure 3, but with the finger protection device in the lowered position, Figure 6shows a view similar to Figure 3 but with the finger protection device in a pulled-up position, and Figure 7 shows a view on a larger scale of the finger protection device.

The machine for fitting rivets, press studs, eyes or the like, on which the invention is embodied, comprises a machine support stand 1 on which a press body 4 is mounted at a suitable working height. A foot operated switch 3 is provided on a base plate 2 of the machine support stand 1 for controlling a press drive motor 30 by way of control means (not shown) arranged on a control panel 5.

Magazines 6 with feed rails 7 are secured to the side of the press body 4. The parts to befitted (rivets, press studs etc.) are supplied by means of the supply rails 7 to insertion tools 8 and 9 of a feed slider 10, which receive the parts and bring them into the correct fitting positions. A pressing thrust member 11 which carries an uppertool 12 is guided movably towards a lower tool 13 in the press body 4 and is moved into the upper rest condition by means of a return spring 14. The lower tool 13 is arranged with a workpiece holder 34 in a cantilever arm 33 whose rearward part is in the form of a slider guide means and which carries the insertion tools 8 and 9 at its front portion.A finger protection means 15 which is in the form of a tongs-like workpiece hold-down means embraces the upper tool 12 and is connected by means of a holder 16 to a finger protection means drive mechanism. The working movement of the thrust member 11 is derived from a main drive shaft 26 which is driven by the press drive motor 30, by means of a drive eccentric 29 which is fixedly disposed on the main drive shaft 26.

The holder 16 of the finger protection means 15 is connected to a control bar 17 which in turn is operatively connected by a guide pin 18 to a second control bar 19 which is disposed parallel to the control bar 17, in such a way that it is displaceable upwardly relative to the control bar 19, overcoming the tension force of a tension spring 20, over the lengthwise distance of a guide groove 21 provided in the control bar 19. The tension spring 20 is secured at one end to the guide pin 18 arranged on the control bar 17, and at the other end to a pin 25 which is fixed with respect to the housing, seeks to pull the guide pin 18 towards the lower end of the guide groove 21 and thus to ensure the transmission of force from the control bar 19 to the control bar 17.In this arrangement, the control bars 17 and 19 which are disposed in one working plane are guided, by way of a guide groove 22 in the control bar 17 and two guide grooves 23 and 24 in the control bar 19, on the one hand on the pin 25 which is fixed to the housing and on the other hand on the main drive shaft 26, in such a way that the control bars are displaceable together towards the lower tool 13 parallel to the thrust member 11 laterally on the press body 4. The two control bars 17 and 19 are driven by a follower roller 27 which is arranged at the upper free end of the control bar 19 and which is guided in a groove in a control cam 28 which in turn is fixedly connected to the main drive shaft 26 for rotary movement.The drive eccentric 29 and the control cam 28 are so matched to each other that the control bar 19 always leads with respect to the movement of the thrust member 11 by a given fraction of a revolution. The control bar 17 carries an electrical contact 31 which co-operates with an electrical contact 32 carried by the control bar 19, for controlling the press drive motor 30. In the event of relative displacement of the control bar 19 relative to the control bar 17, which is triggered against the action of the tension spring 20, if the free downward movement of the finger protection means 15 is interrupted by an obstacle (for example, as shown in Figure 6, by a finger of the operator), the two switching contacts 31,32 will open the control circuit and the machine is instantly braked to a halt.

According to the invention, besides the control cam 28 for driving the control bar 19, a second control cam is provided which may either be in the form of a cam segment 35 provided on the cam 28 or in a separate cam fixedly connected on the main drive shaft 26 for rotary movement. The cam segment 35 co-operates with a follower roller 36 which is secured to the upper end of the control bar 17. The cam segment 35 is of such a dimension and setting, in respect of its configuration and its angular position, relative to the cam 28, and thus also relative to the drive eccentric 29, that, after the finger protection means 15 has been lowered to the safety distance, the cam segment 35 holds the control bar 17 in the lowered position in order thereby to prevent unintentional stopping of the machine under the resistance pressure of elastic thick material.By suitable dimensioning of the angle of action of the cam segment 35, the control bar 17 is released again for an upward movement, when the working operation is concluded.

The mode of operation of the machine according to the invention will now be described as follows: Figures 1 to 4 show the machine in the so-called rest position or charging position in which the members to befitted are set in position. After the workpiece 37 has been inserted, the press drive motor 30 is switched on by actuating the foot operated switch 3, and the main drive shaft 26 is driven with rotary movement. The finger protection means Sand the thrust member 11 are moved towards the lower tool 13 with a shift in respect of Lime, by their drive means.As a result of the relative configuration of the eccentric drive 29 and the control cam 28, the finger protection means 15 is lowered, with a lead, and quickly, towards the workpiece holder 34, while the thrust member 11 with the upper tool 12 initially performs only a slight downward movement, as can be seen from Figure 5 of the drawings. By the time the finger protection means 15 has reached its lowermost position the cam segment 35 with the roller 36 of the control bar 17 has moved into the locking position and thus prevents unintentional upward movement of the control bar 17 and thus opening of the switch contacts 31 and 32 and shutting off of the drive motor 30. This locking position of the control bar 17 is maintained until the upper tool 12 has reached its lowermost point and the working stroke movement is concluded.

If on the other hand, an obstacle such as a finger of the operator, as shown in Figure 6, is in the path of movement of the finger protection means 15, the control bar 17 is displaced with respect to the control bar 19 against the action of the tension spring 20, which is sufficiently weak to exclude any danger of injury, whereby the contacts 31 and 32 are opened and the machine is stopped. This safety function is not prevented by the locking cam segement 35 for, because of the immediate stoppage of the machine, the cam segment 35 does not come into operative engagement with the operative roller 36 if there is an obstacle in the path of movement of the finger protection means 15.

In the single stroke mode, the working machine automatically remains in the rest position by switching off of the drive motor 30; in the continuous stroke mode, the machine continues to run con tinuouslyand begins a new working operation without any interruption.

Claims

1. A machine having an upper tool movable towards a lower tool by an eccentric driven by a main drive shaft, a finger protection guard device disposed around the upper tool and arranged to be moved downwardly with a lead with respect to the upper tool by a cam disc provided on the main drive shaft, the means for moving the finger protection guard device including two members which are force-lockingly connected together and which carry electrical switching means for controlling operation of a drive motorwhich drives the main drive shaft, said two members which carry the electrical switching means being in the form of bars which are arranged parallel to each other, said bars being mounted on the machine parallel to the pressing thrust member which moves the upper tool by means of guide grooves, a guide pin, a mounting pin fixed with respect to the machine housing, and by means of the main drive shaft and are held in contacting engagement with each other by means of a tension spring which is arranged between the pins.

2. A machine as claimed in claim 1, in which a follower roller is provided at the upper end of one bar and a control cam segment which is cyclically set to the sensing movement of the finger protection device is provided on the main drive shaft.

3. A machine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.