GB2043522A - Machine for cutting clay wads - Google Patents

Abstract

A machine for cutting portions of clay from a wad for use in the moulding of flatwear or hollowwear comprises a cutting wire (29) arranged to sever the end of a wad of clay disposed on a conveyor belt (13). A pneumatic piston/cylinder assembly (35) advances the conveyor a metered amount during each operation of the machine and a pneumatic piston/cylinder assembly (37), in the supply line of which is a pressure relief valve, provides drive to the cutting wire 29. If the cutting wire (29) should encounter an obstruction, e.g. an operator's hand, during its downward cutting movement there is an increase in the pressure in the supply line of the assembly (37) which leads to opening of the pressure relief valve thus halting movement of the wire (29). <IMAGE>

Description

SPECIFICATION Machines for cutting clay wads The present invention relates to machines for cutting wads of clay so as to provide the correct amount of clay for moulding flatwear or hollowwear in the pottery industry.

Automatic moulding of pottery wear is becoming increasingly common and to avoid excessive waste of clay it is necessary to ensure that the machine is given only as much clay as it requires for each operation.

It is an object of the invention to provide a machine for cutting metered amounts of clay from a wad thereof-and to provide controls for the machine to reduce the chances of injury to the user of the machine if his hand comes in contact with the cutting mechanism.

According to the present invention there is provided a machine for cutting metered amounts of clay from a wad thereof comprising a cutting mechanism and means for advancing a mass of material to be cut a predetermined amount beyond a plane in which the cutting mechanism operates, the cutting mechanism including a cutting member which is moved across the said plane by a piston and cylinder assembly which is powered by a pneumatic circuit which includes a pressure relief valve arranged in the line by which air is supplied to the piston and cylinder assembly during the cutting movement.The invention will now be described by way of example with reference to the accompanying drawings, in which Figure 1 is a front perspective view of the cutting machine embodying the invention; Figure 2 is a side elevation of the machine shown in Fig. 1; Figure 3 is a view of an enlarged scale of part of the machine shown in Fig. 1; and Figure 4 is a circuit diagram of the pneumatic parts of the machine.

As shown in the drawings, the machine comprises a frame 11 which supports an endless, horizontal, conveyor belt 1 3 which runs around a driven roller 1 5 and a tensioning roller 1 7 mounted for rotation at the two ends of the frame 11. At the driven roller end of the frame 11 is provided a cutting mechanism 19 which comprises a pair of rods 21 mounted within housings 23. The rods 21 are connected together at their ends by upper and lower bars 25 and 27 respectively and a cutting wire 29, e.g. piano wire, is stretched between the rods 21 at an intermediate position.As best seen in Fig. 2, the rods 21 and housings 23 are disposed at an angle of about 1 5, from the vertical and the wire 29, the ends of which are secured in brackets 31 mounted on the rods 21, is so positioned that when the rods 21 are moved downwardly, the wire 29 is brought down to a cutting position at which it co-operates with a horizontal edge 33 of the frame 11. Spaced below the edge 33 is a surface 34 extending from the frame 11 and arranged to receive the pieces of clay cut from the wad by the mechanism 1 9.

The roller 1 5 and the cutting mechanism 1 9 are powered by respective pneumatic cylinders 35 and 37. As best seen in Fig. 1, the cylinder 37 is connected at its lower end to the frame 11 by means of a pivot 39 and at its upper end to the centre of the lower bar 27. The cylinder 35 is mounted on the side of the frame 11 and is connected at its lower end to the frame 11 by means of a pivot 41.

The outer end of the piston of the cylinder 35 is connected by a pivot connection 43 to a curved arm 45, which is drivingly connected, via a one way clutch (not shown) to a shaft 47 of the roller 1 5. The position at which the piston acts on the arm 45 can be varied by loosening a securing screw 49 and sliding the connection 43 along the arm 45.

Operation of the machine is controlled by various switches. A manually operated pneumatic switch 51 mounted on the surface 34 initiates operation of the machine by activating the cylinder 35. The piston of the cylinder 35 carries a rod 53 which is connected at one of its ends to the piston by an arm 55 and at the other end slides through a fixed guide 57.

The rod carries a cam 59 so arranged as to co-operate at the outer end of the stroke of the piston with a pneumatic switch 61. Operation of the switch 61 operates the cylinder 37 to cause downward movement of the cutting mechanism 1 9. At the lower position of the rods 21, a curved member 63 carried by and disposed below the bar 27 actuates a switch 64 mounted on the frame 11. Actuation of the switch 65 causes the pistons of both cylinders 35 and 37 to be returned to their original positions, thus raising the cutting mechanism 1 9 and returning the arm 45 which latter return, because of the one way clutch, is not transmitted to the belt of the conveyor. The switch 65 is, in fact, operated shortly before the piston completes its stroke but a delay is built in to the circuit so that the actual return is not commenced immediately.

This delay feature increases the safety of the machine, since if the cutting wire 29 is obstructed close to the end of its travel, e.g. if the user's hand obstructs the wire close to the surface 34, the wire 29 returns to its initial position.

The details of the pneumatic circuits and parts are shown in Fig. 4. Air from a supply is fed, via a conventional arrangement of filter and pressure regulator 67, oil lubricator 69 and isolator switch 71, to an eight way manifold 73, five outlets of which are connected respectively to the switch 51, to the switch 65, to the switch 61, to an inlet 74 of a first linear slide valve 75 and to an inlet 76 of a second linear slide valve 77. In Fig. 4 the full lines indicate flow of live air, the dotted lines, flow of air to the pilot ports of the slide valves and the chain dotted lines, flow of air to the pistons.

The linear slide valve 75 is air operated and controls the supply of air to the cylinder 35, two outlets of the valve being connected via respective flow control valves 79 and 81 to the upper and lower ends of the cylinder 35.

The linear slide valve 77 is air operated and controls the supply of air to the cylinder 37, two outlets of the valve 77 being connected via respective flow control valves 83 and 85 to the upper and lower ends of the cylinder 37. As seen Fig. 4, the line 86 from the valve 83 to the upper end of the cylinder 37 includes a pressure relief valve 87.

At the start of a cycle of operation, the machine is set with the cylinder 35 in the condition in which its piston is retracted and the cylinder 37 is set with its piston extended.

Manual operation of the switch 51 allows air pass to a pilot port 89 of the slide valve 75 and thus to the lower side of the cylinder 35 causing the piston to extend turning the arm 45 to advance the conveyor belt by an amount determined by the location of the pivot connection 43, thus advancing the forward end of a wad or wads of clay positioned on the belt so that a predetermined amount of clay extends beyond the edge 33.

As the piston completes its travel it operates the switch 61 which connects a pilot pot 95 of the sliding valve 77 to the supply of air and connects an outlet of the valve 77 to the upper end of the cylinder 37, causing the piston to be reactracted and the cutting mechanism to be moved down. The wire 29 cuts through the clay and the piece cut-off falls onto the surface 34. At the end of the stroke of the piston of the cylinder 37, the switch 65 is operated supplying air to pilot ports 93 and 92 of the slide valves 75 and 77, whereupon the valves change to supply air to the lower side of the cylinder 37 and the upper side of the cylinder 35 to return the pistons thereof to their original positions.

If during use of the machine the user should obstruct the movement of the cutter mechanism as the wire is brought down, e.g.

by inadvertantly placing his hand under the wire, the pneumatic system suffers an increase of pressure in the line 86 which leads to opening of the pressure relief valve 87 which halts movement of the wire. The pneumatic circuit is so arranged that the relief valve 87 will open if the pressure in the line 86 rises above about 101b per sq. in.

The flow control valves 79, 81 and 83, 85 control the rate of flow of air in the lines and hence the speed of the working strokes of the pistons of the cylinder 35, 37.

The cylinder 35 has either a 1 inch or a 2 inch stroke (depending on the amount of clay required in each cut) and the cylinder 37 has a-9 inch stroke. Using a roller 1 5 of 6+" diameter an advance of the clay of 4 > " is obtained with a 2 inch stroke on cylinder 35 and the connection 43 located at the inner end of the arm 45 and of 7/8" if the connection 43 is located at the outer end of the arm 45.

Fig. 4 also shows a further activating switch 91 and an isolator switch 93 in parallel with the switch 51 to enable the machine to be operated from a distance, e.g. by a movement of an automatic hollowwear, or flatwear, moulding machine.

Claims (9)

1. A cutting machine comprising a cutting mechanism and means for advancing a mass of material to be cut a predetermined amount beyond a plane in which the cutting mechanism operates, the cutting mechanism including a cutting member which is moved across the said plane by a piston and cylinder assembly which is powered by a pneumatic circuit which includes a pressure relief valve arranged in the line by which air is supplied to the piston and cylinder assembly during the cutting movement.

2. A machine according to claim 1 wherein the said advancing means is a belt conveyor which is driven by a pneumatic cylinder.

3. A machine according to claim 2 wherein a shaft of the driven roller of the conveyor is connected, via a one way clutch, to an arm which is acted on by the said pneumatic cylinder.

4. A machine according to claim 3 wherein the connection between the cylinder and the arm is such that the position at which the piston of the cylinder acts on the arm can be varied.

5. A machine according to any of the preceding claims wherein the cutting member is a wire stretched between two side members of a frame which is mounted for sliding movement on the machine and which is connected to the said piston and cylinder assembly.

6. A machine according to claim 5 wherein the frame slides in a plane at an angle of substantially 1 5, to the vertical.

7. A machine according to any of claims 2 to 6 including a pneumatic switch arranged to be operated by the completion of the stroke of the pneumatic cylinder that is connected to the conveyor and arranged, when so operated to initiate movement of the cutting mechanism.

8. A machine according to claim 7 including a pneumatic switch arranged to be operated by completion of the movement of the cutting mechanism to reactivate the pneumatic cylinders to return the cutting mechanism to its initial position and to reset the cylinder connected to the conveyor.

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