Conveyor

A conveyor having a frame, a piston and cylinder unit operable by means of pressure fluid and secured in the frame, a spring assembly for actuation of the piston, a holder mounted on the frame and reciprocable by means of the piston and cylinder unit and carrying a conveyor path for receiving articles. The piston and cylinder unit has inlet and outlet valves and throttle means at the outlet of the outlet valve. A control rod connected to the piston of the piston and cylinder unit is adapted to allow control of the cross-sectional passage area of the throttle means. The control rod has a back-off section which merges into the full diameter of the rod at one end over a long distance and at the other end over a considerably shorter distance. The conveyor permits moving articles by a throwing movement also along a slightly upwardly inclining conveyor path.

The present invention relates to a conveyor having a frame to be anchored 
to a base, a piston and cylinder unit secured in the frame, a holder 
mounted on the frame and reciprocable by means of the piston and cylinder 
unit, the holder being connected to a path or channel for receiving 
articles and transporting them by the reciprocating movement. 
In the engineering industry, problems are often encountered when articles 
are to be transported from a treatment station to a receiving station or 
other treatment station if but a restricted space is available. It is thus 
difficult, if not impossible, to install an effective roller or belt 
conveyor in conjunction with eccentric or like presses, and therefore the 
articles must often be moved by hand. Attempts have been made to use 
vibratory conveyors which, however, suffer from the drawback of suddenly 
reversing their conveying direction, implying that the articles may be 
returned to the treatment station, causing damage therein. Besides, 
vibratory conveyors operate with a very high sound level, for which reason 
they are doubtful also from the viewpoint of labour safety. 
The object of this invention is to provide a conveyor of very small 
dimensions, which nevertheless very effectively moves articles from one 
place to another and also is of very silent operation. 
To this end, the piston of the piston and cylinder unit is movable in the 
cylinder from a first position to a second position by pressure medium 
under tensioning of spring means adapted to at least contribute to 
returning the piston to the first position, and the piston is adapted to 
control inlet and outlet valves for the pressure medium so that the supply 
of pressure medium is suddenly interrupted when the piston reaches the 
second position, and so that the pressure medium in the cylinder is 
delivered at first slowly and then ever more rapidly when the piston is 
moved by the action of the spring means from said second position to said 
first position in which the outlet valve is suddenly closed and the inlet 
valve is opened.

The illustrated conveyor comprises a fastening means in the form of an 
angular bracket 27 intended to be secured to e.g. a press table. A 
supporting means 23 is fixedly connected to the angular bracket 27 and in 
turn carries a piston and cylinder unit with associated valves, shown in 
the center of FIG. 1, and sleeves 35 arranged on either side of the piston 
and cylinder unit. Pins 34 are movable in the sleeves 35 and said pins are 
connected with each other and with the piston by means of a yoke member 12 
which in turn carries a holder 11. The conveyor path or channel (not 
shown) is rigidly connected to said holder 11 and extends along it, as 
this holder is viewed in FIGS. 2 and 3. The conveyor path or channel will 
thus be reciprocated in concert with the movement of the piston of the 
piston and cylinder unit and that of the pins 34 in the sleeves 35, 
respectively. 
The piston and cylinder unit, illustrated more in detail in FIG. 3, is 
utilized to reciprocate the holder 11 and thus the conveyor path or 
channel. Said unit comprises a cylinder 13 in which a piston 9 of 
considerably smaller length than that of the cylinder 13 is reciprocable. 
The piston 9 is sealed in relation to the cylinder wall by means of 
O-rings 7. The piston 9 has an axial bore 41 in which an annular shoulder 
42 is formed at some distance from the left end of the piston 9, as viewed 
in FIG. 3. A shaft 10 extends through the bore 41 of the piston 9 and 
projects a considerable distance to the left in FIG. 3. On this projecting 
part the shaft 10 carries valve closure members 15 and 21, which are 
spaced axially apart and have packings 16 in their facing sealing 
surfaces. Between the valve closure members 15 and 21 a valve housing 18 
is sealingly and immovably connected to the inner surface of the cylinder 
13. The shaft 10 is supported in the valve housing 18 partly by the 
housing itself and partly by a nipple 17 axially arranged in the housing 
and also forming the valve seat 39 of the valve closure member 15. The 
nipple 17 is sealed in relation to the shaft 10 by means of an O-ring 19. 
Coaxially with the valve seat 39 the valve housing 18 has a second valve 
seat 40 with which the valve closure member 21 cooperates. Said valve 
closure member 21 is fixedly connected to the shaft 10 by means of locking 
rings 20 on either side of the valve closure member, while the valve 
closure member 15 is fixed to the end of the shaft remote from the piston 
9 by means of a screw 14 which engages in the shaft end. 
The seat 40 embraces an opening of somewhat larger diameter than that of 
the shaft 10, said opening being connected to a bore which extends at 
right angles to the shaft direction and in which a throttle means 4 is 
fixed. The throttle means has a passage 5 extending coaxially with said 
bore and opening into a transverse passage 6 which runs in parallel with 
the shaft 10 and through which extends a control rod 2. At the right-hand 
end, as viewed in FIG. 3, the control rod 2 is connected to the yoke 
member 12 by means of a screw 30. As earlier mentioned, the yoke member 12 
is connected to the piston 9 by a connecting element 24. When the piston 9 
is reciprocated, the control rod 2 is thus also moved back and forth. The 
control rod 2 at its underside has a milled section 31 which reduces the 
cross-sectional area of the rod 2. This milled rod section of reduced 
cross-sectional area is of a predetermined length and, as appears from 
FIG. 3, said section at the front end approaches the full dimension of the 
rod gradually, whereas it more abruptly merges into the full cross-section 
at the rear end. The passage 6 into which the rod 2 penetrates is of a 
slightly larger cross-sectional dimension (say 0.1 mm) than the rod which 
therefore is readily movable in the passage and with the aid of the 
recessed section 31 is able to regulate the free cross-sectional area of 
the passage. The throttle means 4 upstands from the upper surface of the 
cylinder and is there encircled by a cylindrical sound damping device 3 
which has a bottom member connected to the outer wall of the cylinder, and 
an internal covering 26 of sound damping material. The rod 2 extends 
through opposite openings in the sound damping device 3 and the covering 
26. A plate 1 is sealingly fixed on top of the throttle means 4 and the 
sound damping device 3, and one end of said plate 1 protrudes freely while 
the other end thereof is connected to the outer side of the cylinder wall 
by means of a fastening element 29. The plate 1 above the throttle means 4 
has a threaded opening into which is screwed a screw 45. In its upper side 
the throttle means 4 has a recess 43 with a washer 44 therein, against 
which bears the end of the screw. With the aid of said screw the throttle 
means 4 can be so actuated as to change the dimension of the passage 6, 
whereby the rate of movement of the piston 9 and thus the conveyor path 
can be varied. In the bore of the piston 9 there is arranged a spring 8 on 
the side of the shoulder 42 facing the valve closure member 21, while a 
spring 22 is arranged on the opposite side of the shoulder 42. The 
function of the springs 8 and 22 will appear from the following. 
The sleeves 35 disposed on either side of the piston and cylinder unit are 
fixed to the angular bracket 27 by means of the connecting element 23 and, 
as already mentioned, each sleeve houses a pressure spring 33. A pin 34 
connected to the piston 9 by means of the yoke member 12 penetrates into 
each sleeve 35. The pins are mounted in their sleeves by a bushing 36 at 
one end of the sleeve and a washer 32 at the other end of the sleeve, said 
washer being connected to the pin 34 by means of a screw 37. The outer 
dimension of the washer 32 is smaller than the inner dimension of the 
sleeve 35, and the washer engages the inner surface of the sleeve via an 
O-ring 25. The spring 33 in the sleeve 35 at one end bears against the 
washer and at the other end against the inwardly facing surface of the 
bushing 36. It appears from FIG. 2 that if the pin 34 is moved to the left 
the washer will be moved into the sleeve 35 under tensioning of the spring 
33. 
The apparatus described above functions in the following manner. It is 
assumed that the angular bracket 27 is mounted on a supporting surface and 
that a conveyor channel is secured to the holder and extends 
longitudinally of the cylinder 13 and the sleeve 35, respectively. A 
compressed air line is connected to the left end of the cylinder 13, as 
viewed in FIG. 3. The conveyor channel carries articles e.g. of metal to 
be transported. The piston and the valves occupy the position shown in 
FIG. 3. Compressed air which is now supplied through the compressed air 
line will pass the valve closure member 15 because the inner dimension of 
the cylinder is larger than the outer dimension of the valve closure 
member 15. The valve closure member 15 is spaced from the seat 39 for 
which reason the compressed air flows through the seat into the axial 
opening of the nipple 17 and from there through a passage 28 which extends 
through the wall of the nipple 17 and that of the valve housing 18 and 
continues to the right past the valve closure member 21 the outer 
dimension of which is also smaller than the inner dimension of the 
cylinder. Thus the compressed air reaches the left end of the piston 9 and 
said piston is thereby moved rapidly to the right. As indicated in FIG. 3 
the spring 22 is shorter than the space in which it is located, and for 
that reason it offers at first no resistance to said movement to the right 
of the piston 9. After the piston 9 has travelled a certain distance the 
right end of the spring 22, however, reaches the shoulder 14 on the shaft 
10 (said shoulder is formed by a screw head) and thus begins to be 
tensioned. Having been tensioned to a certain degree, the spring actuates 
the shaft 10 so that the shaft is rapidly moved to the right, implying 
that the valve closure member 15 fixedly connected to said shaft is 
brought into contact with its seat 39, whereby the supply of compressed 
air suddenly ceases and the movement of the piston 9 is stopped. When the 
shaft 10 is moved to the right the valve closure member 21 is also moved 
to the right so that the valve formed by the seat 40 and the valve closure 
member 21 is opened and the compressed air contained in the cylinder can 
start escaping. At the movement of the piston 9 to the right the control 
rod 2 has also been moved to the right so that the left end of the milled 
section 31, that is the point where the section merges into the full 
cross-section of the rod, is located in the transverse passage 9 above the 
passage 5. This implies that the escape of air through the seat 40 is 
throttled. At the movement of the piston 9 to the right the springs 33 in 
the sleeves 35 have also been tensioned and they now carry out a return 
movement of the piston 9 to the left. The movement is restricted as the 
flow of the compressed air into the passage 6 is throttled, but it will be 
realized that according as the piston 9 moves to the left the 
cross-sectional outlet area of the passage 6 will increase and the 
movement of the piston 9 will accelerate, that is, the initially slow 
movement of the piston 9 and thus of the conveyor channel is accelerated 
after a predeterminable period to a rate corresponding for instance to the 
piston speed in the opposite direction. When the piston 9 begins to 
approach the position, shown in FIG. 3, the spring 8 is tensioned against 
the rear of the valve closure member 21 and when the spring has reached a 
predetermined tension it moves the valve closure member 21 to the left 
together with the shaft 10. At this moment the the discharge of compressed 
air through the passage 6 also abruptly ceases and compressed air again 
begins to enter through the seat 39, a new cycle being thus initiated. 
Since the milled section 31 at the right end of the rod 2 merges into the 
full cross-section of the rod 2 over a much shorter distance than at the 
left end of the rod, the acceleration of the piston takes place to maximum 
speed in this position, as is graphically illustrated in FIG. 5, which 
shows the movements of the piston 9 and of the conveyor channel as a 
function of time. 
By the described movement, graphically illustrated in FIG. 1, of the piston 
9 and the parts fixedly connected therewith the articles in the conveyor 
channel will be safely conveyed in one direction. The channel accelerates 
from standstill relatively slowly in a forward direction until a maximum 
speed is attained, whereupon the movement of the channel is reversed and 
the channel immediately moves at maximum speed in the opposite direction. 
The movement will be some kind of a throwing movement by which one can 
even cause the articles to move along an upwardly inclined path (a maximum 
of about 8.degree. upward inclination). By screwing down the screw 45 the 
dimension of the passage 6 is reduced at right angles to the milled 
section 31 of the rod 2, resulting in a smaller air quantity being 
delivered when the left end of the section 31 reverses its direction of 
motion in the passage 6, making the acceleration slower, i.e. the channel 
reaches its maximum speed in a longer time. With the screw 45 screwed to 
the bottom the movement of the piston and thus of the channel comes to a 
standstill. The conveyor operates very reliably and effectively. As the 
consumption of compressed air furthermore is extremely low and the sound 
of escaping compressed air is effectively dampened, the conveyor according 
to the present invention involves a considerable technical advance.