SU1416307A1 - Apparatus for monitoring the process of pressing - Google Patents

Abstract

The invention relates to the woodworking industry. The purpose of the invention is to improve the quality of control over the extrusion process, for example, when working with differently thick plywood. The device is made in the form of a pneumatic cylinder, forming a pneumatic cavity of variable volume, valves 8, 10, and an additional receiver tank 11. The piston rod 6 of the pneumatic cavity is kinematically connected with the lower plate of the press. The change in pressure in the pneumatic cavity is sensed by sensor 12. 2 Il.

Description

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The invention relates to the woodworking industry - and grows | be used in the manufacture of plywood and plywood boards.

The purpose of the invention is to improve the quality of control over the pressing process.

FIG. 1 is a block diagram.

ty p v

: control devices, realizable by JQ. Plates 1 will be (derived from dependency; when pressing plywood on a high-rise press; FIG, 2 is static

: device characteristics by channel

: stroke (H) of the cylinder rod - signal (P),

i arriving at the sensor control. 15

i The device includes a multi-storey

I press having a lower movable

I plate 1 with the support fixed on it 2. The press plate, having moved,

 from bottom to top (conditionally shown) hedgehogs 20

1 packs 3 veneers between the plates 4

press. The control device consists

from pneumatic cylinder 5 with rod 6, the upper part of which is complete in the form

the plunger 7, the valve 8 is reset, pneu-25; line 9, bypass valve 10: receiver 11 and sensor 12 control. I Pneumatic 5 fixedly mounted

on the bed or the top plate of the press. The device works as follows- 30

at once.

The press is loaded with veneer packages.

3, having the same amount

layers of veneer. A start command is issued.

 const

P -Ei-yi.-,

 V - HS

where P is the sensor reading, for example

angle of rotation, 0; y, - the volume enclosed in the cylinder 5 between, at the plunger 7 and pneumolink 9 when the rod 6 is in the lowest position, m;

H is the stroke length of the rod 6, m, S is the surface of the barb 7, m, P, is the pressure above the rod when it is found in its lowest position, front, P 0.1 MPa (atmospheric pressure).

Considering that the value of P in. the lowest position for all press cases in a hermetically sealed container is constant, the value of V | gfi closed valves 8 and 10 are constant, the surface S is unchanged, depending on the press plates are compressed. The stop 2, the reading from the stroke of the plumbing with the rod 6, acts on the air in the pneumatic cylinder 5.

There are two cases of work of the urt. Devices on the press, which produce plywood, for example, of two thicknesses: from seven 40 ply veneer and from thirteen ply veneer.

In the first case, packages of a maximum thickness of 360 mm are extruded from a thirteen-ply 45 device reinforcement through the veneer channel. At the same time, pressure relief valve 8, press lug 1, the sensor reading and valve 1-0 are in the closed state. The press plate can move the pluker 7 in the lower hour of the cylinder 5, i.e., E of this part, in this case, there is an area in which it is necessary to control the thickness of the iivbix veneer sheets,

The rod 6 with the help of the piston 7 compresses the air located under the plunger packages of 13 layer veneer, zherom. In this case, the overpressure is shown in FIG. 2, curve 1; The air is transmitted through the air passage; it can be seen that the limit value of water 9 to sensor 12, which by magnitude P corresponds to the stroke of the rod, does not change; pressure is fixed at 0.3 m

50

you will be 1

,

  V 2 V and K b.jK

where K, K, K are constant coefficients.

It follows that with an increase in the stroke of the rod, the

12. This circumstance allows more precise control over the pressing process at the final stage: when it is necessary to control the amount of plywood pressing.

Static characteristic of the reading value P of sensor 12 from the stroke N of the press plate for the case of pressing

press plates, and therefore, allows you to control the process of pressing.

When a pressure sensor 12 is linearly converted into a control signal, for example, the angle P of the sensor arrow, the relationship between the sensor reading 12 and the stroke

ty p v

 const

P -Ei-yi.-,

 V - HS

de P - sensor reading, for example

angle of rotation, 0; y, - the volume enclosed in the cylinder 5 between, at the plunger 7 and pneumolink 9 when the rod 6 is in the lowest position, m;

H is the stroke value of the rod 6, m, S is the surface of the Shch1shir 7, m, P, is the pressure above the rod when read from the stroke of the plate

 amplification of the device through the channel stroke 1 pltsy - sensor reading

you will be 1

,

  V 2 V and K b.jK

where K, K, K are constant coefficients.

It follows that with an increase in the stroke of the rod, the

 amplification of the device through the channel stroke 1 pltsy - sensor reading

packages of thirteen-layer veneer, is presented in FIG. 2, curve 1, from which it can be seen that the limit value of the reading P corresponds to a stroke of 0.3 m.

12. This circumstance allows more precise control over the pressing process at the final stage: when it is necessary to control the amount of plywood pressing.

Static characteristic of the reading value P of sensor 12 from the stroke N of the press plate for the case of pressing

3

In the second case, plywood from a seven-layer pton with a maximum bag thickness of 140 mm is manufactured on the press. At the same time, valves 8 and 10 open, connecting the internal cavity with the atmospheric and internal volume of the receiver 11. When moving from the lowest position, the plunger 7 pushes air through the valve 8 into the atmosphere until the plunger blocks the pneumatic line connecting the Grshindra cavity to the valve 8 pressure relief. At this point, the total volume of air located above the plunger 7 is

V

V / + V.

., vp,

where Vp is the internal volume of the receiver,

the volume enclosed in the cylinder 5 between the plunger 7 and the pneumatic line 9 while the plunger is located / at the level of the pneumatic line connecting the cavity of the cylinder with the valve 8

pressure release, m. In this position (when the air volume is Vj), the press plate moves the plunger 7 to the second half of the cylinder 5, i.e. to the zone where at the moment it is necessary to control the thickness of the package being pressed, and the air pressure above the plunger remains equal to atmospheric P. Next, the rod 6, interacting with the press plate 6, the plunger 7 begins to compress the air located above the plunger 7. In this case, the sensor 12 converts the overpressure into

control, similarly indicated when new signaling

d

dependence

cheni x and c

and

 Pi.Yt.

V. -HS

 PI.Y,

V

Where

H value of the stroke of the rod 6 in the second half of the pnevaggilliner 5, mm;

Taking into account that the pressure Pj- (atmospheric pressure) is constant during the movement of the plunger 7 until the moment when the hole connecting it

change et- const

valve 8 then pressure p2

c according to the known law P

P V from the value of P ,, to

2

-1 where V- is the volume enclosed between

plunger 7, pnevmolinii 9 and receiver 11 when you find kk plugs 7 in the zone of the second half of the pnevmots1-1linder 5, m

Q 5

0

6

0

five

0

The sensor signal changes with the coefficients 1-; the condition is equal to the previous one (Fig. 2), and the working area is divided into two equal sections, hence the measurement accuracy of the movement of the lower press plate while maintaining one primary converter; Shchindra 5.

FIG. 2 shows experimentally removed static characteristics. obtained by operation of cylinder 5, having a stroke of 6 - 0.6 m. Curve 1 corresponds to the change in pressure supplied to sensor 12, when a press presses plywood from 13-layer veneer. Under these conditions, the maximum stroke of rod 6 is limited to 0.3 m from the lowest (position extended from cylinder 5) position. Valves 8 and 10 are closed. Curve 2 corresponds to the characteristic of the device when seven-layer plywood is pressed and valves 8 and 10 open.

Analysis of the obtained characteristics shows that the proposed device has the same static characteristics, which have the maximum transfer coefficient pv cd cylinder rod stroke - pressure P supplied to the sensor control when pressing plywood of various layers. This makes it possible to increase the accuracy of measuring the magnitude of the stroke of the lower plate of the press, to achieve maintaining the thickness of the pressed sheets of plywood with a smaller spread, and to obtain plywood of higher quality.

45

Claims (1)

Invention Formula Device for controlling the pressing process, including cylinder 50 with a rod, the lower part of which interacts with a movable press table, a control sensor, characterized in that, in order to improve the quality of control, it is equipped 55 is a receiver, a relief valve, a pressure relief valve, the upper part of the rod being made in the form of a movable plunger, which forms a pneumatic container connected to .514163076 pnevmolinii with sensor control and at the same time the internal cavity of the cylinder is connected to the pressure relief valve through the valve bypass valve with the receiver. 0, YuU) ABOUT 0, Z5 fig, g 0.5 N, m