US2907555A

US2907555A - Mixing apparatus

Info

Publication number: US2907555A
Application number: US499711A
Authority: US
Inventors: Engels Kaspar
Original assignee: Draiswerke GmbH
Current assignee: Draiswerke GmbH
Priority date: 1954-05-08
Filing date: 1955-04-06
Publication date: 1959-10-06
Anticipated expiration: 1976-10-06

Description

Oct. 6, 1959 K. ENGELS MIXING APPARATUS 2 Sheets-Sheet 1 Filed April 6, 1955 K W a Oct. 6, 1959 K. ENGELS 7 2,907,555

MIXING APPARATUS Filed April 6, 1955 2 Sheets-Sheet 2 y gall a; gal

r i 7' 7' 1 50 30 I 30 an a A a 0 2 l/ o o o 0 0 Inventor United States Patent ice The invention relates to an improved mixing apparatus and is concerned with apparatus adapted for-the con tinuous mixing of a liquid with bulky divided material. This latter term is to be understood to include masses of divided material such as shavings, flakes, fibres chips and so on.

A primary object of the invention is to provide an apparatus particularly adapted for the mixing of Wood shavings with a bindingagent, for example a synthetic resin adhesive, the mixed product serving subsequently for the production of wood-shaving sheets, for example. The mixing of liquid with other substances in flake or fibre form is also included within the said object. An arrangement according to the invention is particularly suitable for mixing a relatively large bulk of shavings with a relatively small amount of wetting agent in such manner that the wetting agent is distributed as uniformly as possible throughout the bulky material..

For purposes of this kind rotating drums have hitherto been known, in which the material to be mixed is changed and wherein are agitating mechanisms which toss up the shavings, the latter being sprayed as they fall freely. In relation to the large size requiredforthe drums, the quantitative output of mixing arrangements of this kind is very low. The desired uniform distribution of the binding agent over the surface of the shavings is inadequate. So-called free-fall mixers are also, known which comprise a vertical duct or shaft, to which the material to be mixed is supplied by means of an air eddy at the upper end. The shavings gradually fall downward in the duct or shaft and the binding agent is added as they fall. In this case too, aims and uniform distribution of the binding agent over the shavings is not possible, particularly since the heavier shavings fall more rapidly through the duct or shaft than the small, lighter shavings.

In contradistinction thereto, it is proposed according to the present invention to use a known trough mixer comprising an agitator to which the bulk material to be treated with liquid is fed through a hopper at one end of thetrough but in which the discharged opening for the. treated material is located at the opposite end above the agitator. shaft. The mode of operation is preferably such that the internal space of the trough which is sealed WithJa cover, is quantitatively so charged with the, bulk material that, atthe start andwhen the agitator I shaft is stationary, the trough is filled from 50 to 70 per-. cent with the said material. The discharge opening for 2,907,555 haunted on. e, 1959 ample a binding agent, is uniformly distributed over the surface of the shavings.

A toothed roller or paddle device, which is advantageously arranged to be vertically adjustable, isadvantageously provided at the discharge opening, and is driven at a suitable speed so as to promote and regulate the discharge.

It has proved advantageous to construct the trough mixer as a container of elliptical cross-section, and to provide the agitator with agitating arms of simple rod form. The extremities of these arms are preferably situated at some little distance from the inner Wall of the trough. With this arrangement, the bulk material is completely uniformly treated with the wetting liquid, and it is of special significance that there is an avoidance of the formation of lumps which would obstruct the operation of the agitator. The material passes through the agitator with a steady flow, the entire contents being uniformly distributed over the cross-section of the container during operation.

A vertically adjustable bafile plate is advantageously provided at the outlet opening of the trough and also at the inlet end of the container, namely at the point of transition from the charging hopper to the container. The baffle plate at the discharge opening additionally regulates the quantitative discharge of the treated material. The bafile plate at the charging hopper end prevents the material from returning towards the'charging hopper. l

Lifting means may be provided whereby the trough or container may be given any desired end-to-end inclination. By the aid of such means it is possible to adapt the working to suit the different requirements of various bulky materials. It has proved, however, that in mixing wood shavings with a. binding agent the arrangement according to the invention works perfectly even'when the trough or container remains adjusted in the horizontal position.

The supply of the wetting liquid, for example a binding agent, is effected in the usual way with the'aid of nozzles. If these nozzles are used with a trough or container provided with a cover, it is advisable to provide apertures in such cover end to dispose the nozzles a short distance outside of the cover and opposite respective apertures. only slightly larger than the diameter of the jets produced by the nozzles. As the nozzles are situated externally, the risk of their being fouled or obstructed by matter churned up by the agitator is completely precluded. The perfect operation of the nozzles maybe continually observed from outside and the desired quantitative addition of wetting liquid maythus be accurately supervised. Furthermore, through the injection ofthe liquid jets, an induced inflow of air is produced at the apertures and gthis prevents any substances: from leaving the apparatus through such apertures.

I It is advisable to provide the trough or container with an air-suction device, so disposed as to draw the sprayed air through the bulk material.

. The agitatorshaft is advantageously driven through an infinitely variable gear, so as to afford the possibility of conveniently meeting any working conditions.

In the annexed drawing:

Figure 1 is a longitudinal section of one example of mix-ing apparatus embodying the invention,

Figure 2 is a cross section on the line llallwin Figure 1, l j l Figure. 3 is a longitudinal section of a ample, l

second exa Figure 4 is across section on the line lye-JV in F ig f ure 3,- and is The diameter of these apertures is made to be V of the treatment.

FiguregS is a sectional elevation to a larger scale of afragment of Figure 3.

The mixing apparatus in Figures 1 and 2 comprises an elongated container 1 of trough-like form, the bottom being semi-cylindrical and the side walls being vertical and parallel with one another. Within and longitudinally of this container there is rotatably mounted arr-agitator consisting of a shaft 2 and agitating arms 3. The agitating armsor rods 3 are in axial spaced .relationshipat a distance from one another substantially greater than the thickness of said rods longitudinally of the shaft 2. The shaft 2 is mounted in the end walls t and 5 of the container 1, the central longitudinal axis .of the shaft 2 coinciding with that of' the semi-cylindrical bottom, or being disposed a few millimetres above the latter axis, if desired. The trough is provided with an easily detachable cover 6, at one side of which are situated liquid injector spray nozzles 7, which are directed against the direction of rotation of the agitator as indicated by arrows in Figure :2. 7

Wood shavings are supplied to the container through a feed hopper 8. On rotation of the agitator 2,3, the shavings more or less fill out the trough in the manner illustrated in Figures 1 and 2, and a binding agent, for example a synthetic resin adhesive, is sprayed through the nozzles 7 onto the shavings in the manner'shown.

A discharge opening 9 is situated in the end wall 5 of the trough above the agitator shaft 2, namely in the region of the height of the free ends of the agitating arms 3 as they come to the top or" the circle which they describe in a revolution. A toothed roller or paddle device 1i}, which is suitably driven in a manner not illustrated, is mounted at the discharge opening 9. The material fed in at the hopper 8 is intimately mixed with the binding'agen-t and is discharged through the opening 9 whereupon it falls down a chute 11 ready for further treatment or Working up. The paddle device 1i) 7 additionally regulates the uniform discharge of the treat ed material and such paddle device may be supported so as to be vertically adjustable to suit different discharge requirements.

An adjustable lifting means such as a screw jack 13 operated by a hand wheel 14, is mounted on abase or stand 12. The upper end of the jack 13 is pivotally connected to an eye 15 on the underside of the container 1. This arrangement enables the end to end inclination of the container in relation to the horizontal to be varied, to suit the different requirements of various materials to be treated.

The agitator shaft 2 is driven through an infinitely variable gearing of the V-belt pulley type. in this type of gearing the V belt pulleys comprise

side parts

16, 16a and 17, 1711 which are adjustable towards and from one another for altering the eifective diameters of the pulley surfaces engaged-by the V belt 18, in a known manner. A variable drive is thus'transmitted from a driving shaft 19 through the V belt 18 to the agitator shaft 2.

According to Figure 2 a duct 21 extending down one side Wall Ztlof the container 1 has an enlarged portion 22 at the top for the accommodation of an air-suction de. vice. The duct 21 opens at its bottom end into" the lower part of the container so that the suction device in the portion 22 is effective for drawing through the shavings:

or other material under treatment air or air charged with mist derived from the spray nozzles 7. The capacity of the suction device, or the speed at which it is run, will be chosen to suit the material treated and the nature .In Figures 3, 4 and 5, the container 1 is so mounted at the 'outset on the

uprights

23 and 24 that it lies horizontally. The agitator shaft 2 with the agitator arms 3 is again mounted in the end walls 4 land 5. The agitator arms consist of simple round bars with pointed ends andtween. As will be seen from Figures 3 and 4, even the arms of greater length have their pointed ends at a distance from the walls of the container.

The agitator shaft 2 is driven from a motor 25 through an infinitely variable gear 26 and a plain belt drive 27.

The container 1 in this example is substantially elliptical in cross-section the term elliptical being used in a wide sense to include the cross section seen in Figure 4 which is oblate and not strictly elliptical. preceding example, there is a charging hopper 8 at one end. At the opposite end a discharge opening 9 is disposed well above the bearing for agitator shaft 2 on the end wall 5 and is opposite the tips of the arms 3 as these reach the top of a revolution. A driven toothed roller or paddle device '10 is disposed here just outside the discharge opening 9 anda slidable baffle plate 28 is mounted on the end wall 5 so as to be vertically'adjustable over the discharge opening This adjustable baflle 28 provides an additionat means for enabling the rate of discharge to be regulated. A vertically adjustable bafiie plate 29 is alsoprovided at the transition from the hopper 8 to the container 1 and this baiile 29 prevents any return of the material towards the hopper 8 and thereby avoids any obstruction of the charging operation.

Apertures 30 are provided in the top of the container 1, to which are allotted respective spraying nozzles 31.

These latter are situated outside of the container and serve for supplying the wetting liquid, for example a the injector effect referred to, it is not possible for the in-thisexample the arms at the two ends and in the nozzles to be fouled or clogged by solid matter emerging from the container when this arrangement is in continuous operation.

If the container is charged with shavings, for example, up to about 70% of its total capacity when the agitator is stationary, as indicated by the line a in Figure 4, and

if the agitator is-then set in motion, the shavings are first mixed with air, namely in such manner that said shavings have a churning and flowing movement and fillout the total cross section of the container to a greater or lesser extent. The agitating arms, consisting of iron rods, unobstructedly engage through this churning mass of shavin gs. A loose surface frictionof the shavings against one another ensues so that a relatively small quantity of binding agent supplied by the nozzles 31 is uniformly distributed over the surface of the shavings. An amount of treated shavings corresponding to the amount fed in at the hopper 8 then leaves the container at the outlet opening 9 through a discharge duct 32. p

Where in the claim reference is made to the rods presenting operating front portions extending substantially' parallel to the direction of material transport, it is intended toinclude among such front portions relatively sharp edges, flat surfaces or even cylindrical rods along the front surface of which the contents pass in parallel direction. v

I claim: I

A mixer for the treatment of bulky divided material such as flat wood shavings with a liquid binding agent such .as a resin comprising in combination an elongated container disposedsubstantially horizontallyand having a top surface and an larcuate bottom surface, .a .shaft disposed in' said container substantially parallel with the longitudinal axis of said bottom surface, means for ro-v tatably supportingjsaid' shaft, a plurality of relatively narrow rods secured to said shaft axially spaced re1a- As in the tionship at a distance from one another substantially greater than the thickness of said rods to permit passage of broad chips therebetween and extending radially thereof, said rods being of a length such that their ends pass close to the arcuate bottom surface of said container when said shaft is rotated, charging means for introducing bulky material into said container at one end thereof, spray nozzle means arranged in aspirating relation along the top surface of said container for directing a spray of liquid binding agent into said container, and discharge means for the treated material arranged at the other end of said container, said discharge means comprising a discharge aperture in the end plate of said container arranged at a level higher than the axis of rotation of said shaft and a paddle wheel having a shaft disposed transversely of the longitudinal axis of said container and of said shaft supporting said rods and mounted in operative relationship to said aperture, said rods presenting operating front portions extending substantially parallel to the direction of material transport axially of said container in a manner to effect essentially circular stirring motion at right angles to the direction of material transport and being operative to maintain in combination with said charging means a substantially uniform upper material level in gravity feed relation to said discharge means.

References Cited in the file of this patent