ADJUSTABLE DOSING DEVICE FOR PULVERULENT MATERIAL

Abstract: The invention relates to a device for controlled feeding of particulate, flowing substance. The device consists of an outflow part (1) of a vessel containing the substance to be fed and a proportioning disk (4) rotated underneath its mouth opening at an operational clearance, a flow guiding structure (12) formed at the mouth opening of the outflow part (1) and opening spirally in the rotation direction of the proportioning disk (4) and forming an out flow opening (8), and a doctor blade (5) mounted away from the outflow opening (8) in the rotation direction of the disk for the purpose of removing the material from the disk. The diameter of the mouth opening of the outflow part (1) is no more than approximately half of the diameter of the proportioning disk (4), and the doctor blade (5) is placed at a distance of at least approximately half a rotation away from the outflow opening (8) in the rotation direction of the proportioning disk (4).

Description: ADJUSTABLE DOSING DEVICE FOR PULVERULENT MATERIAL The invention relates to a disk feeder by means of which particulate, flowing material can be fed in a controlled manner through a mouth opening in a bottom cone of a vessel containing the material. The term controlled feed¬ ing is used in this connection to include both continuous feeding and intermittent feeding, and so that the term proportioning can also be used when referring to either of these functions. As a feeding device the equipment includes a rotating disc placed underneath the mouth opening in the bottom cone, which disk feeds the material flowing through the opening to an appropriate receiving device for further conductance. In order to regulate the amount of the material to be fed, the rotation speed of the disc can be adjusted and the device includes control and regulation elements functioning in conjunction with a flow opening formed at the mouth opening. The material guided onto the disk trough the mouth opening in the bot- torn cone is removed from the disk by a doctor blade plac¬ ed downstream of the flow opening in the rotation direc¬ tion of the disk. The devices of the aforementioned kind are as their basic construction prior known, and they can be considered to function properly in the proportioning of several kinds of flowing substances. However, when the said known art devices are used in controlled feeding, i.e. for propor¬ tioning substances which are difficult to handle, essen- tial problems arise. There are basically two types of the aforementioned substances which are difficult to handle, namely those that flow with difficulty and those that flow too readily. Substances that flow with difficulty tend to come out of the flow opening unevenly, at times abundantly and at other times the flow may be interrupt¬ ed. When handling readily-flowing substances, on the other hand, it is difficult to achieve a self blocking effect of the material flow when applying the intermit- tent proportioning; i.e. although the proportioning disk is at standstill, the substance tends to flow out of the flow opening and further over the proportioning disk to a discharge opening. In accordance with the invention, the problems associated with these known art devices have been eliminated by di¬ mensioning the diameter of the mouth opening of the out¬ flow part to be approximately half of the diameter of the proportioning disk and by placing the doctor blade in the direction of rotation of the proportioning disk at a dis¬ tance of at least about half a rotation from the flow opening. The said structural arrangement results firstly in that the substance flowing from the flow opening of the bottom cone forming the out flow part has a longer distance than hitherto over which to accumulate so that a readily flo¬ wing substance can form a barrier to its spontaneous flow and thus prevent the unintentional flowing of the subs¬ tance over the proportioning disk in the standstill of the disk between the proportioning periods. On the other hand, during the proportioning event, with the propor¬ tioning disk rotating, the substance being proportioned is forced to travel along the disk for a distance essen¬ tially longer than is the case with previous structures as well as being forced to move, rolled along by the dis¬ charge doctor blade, in the direction of the disk's di¬ ameter for a longer distance. On being transferred ra- dially towards the periphery, the peripheral velocity of the substance increases, and this, together with the doc¬ tor blade's rolling effect, causes accumulations possibly formed in the flow of material to collapse, and thereby results in a more uniform flow of the material. The invention is presented in more detail by means of the appended drawing in which Figure 1 illustrates a bottom cone forming the lower part of a vessel containing the substance to be fed, the mouth opening in the said cone being constructed in accordance with the invention, Figure 2 illustrates a proportioning disk, Figure 3 illustrates an enclosure structure for en- closing the bottom cone and the proportioning disk, and Figure 4 illustrates the mutual arrangement of the proportioning disk, the mouth opening in the vessel and the enclosure structure. In Figure 1, reference number 1 points to a conical lower part of a vessel whose mouth opening has been constructed to form an out flow opening 8 defined underneath by a proportioning disk 4 according to Figure 2 and placed to abut against the conical lower part. The inside edge of the out-flow opening is formed by the mantle of the coni¬ cal part, the bottom edge of the said mantle having a low guiding rim 13. The said guiding rim projects spirally inwards from the out flow opening by about a quadrant, and approaches the centre of the conical part. Likewise, the outside edge of the out-flow opening 8 has been con¬ structed to form a spirally outwards opening guiding structure 12 whereupon the inside and outside guides de- fine between them a flow route widening spirally in the rotation direction of the proportioning disk 4. In accordance with one of the invention's fundamental characteristics, the diameter of the mouth opening of the conical part 1 is no more than half of the diameter of the proportioning disk 4. Another fundamental character¬ istic of the invention becomes evident from Figure 4, in which the doctor blade 5 is placed at a distance of ap¬ proximately half a rotation from the out flow opening 8. The said distance may be considered as being the minimum distance for ensuring a flow route that results in suffi- cient evening of flow along the proportioning disk 4 for the substance being proportioned. While the doctor blade may be placed even slightly further away from the dis¬ charge opening, placing it too far within the area of the external spiral guide 12 is not recommended. A significant additional characteristic of the invention is illustrated in Figure 2 where loosening elements 11 have been mounted onto the proportioning disk. The said elements"make it possible to enhance the efficiency of the device when dealing with difficult-to-handle sub¬ stances. The loosening elements have been mounted onto a vertically oriented extension of the rotation axle of the proportioning disk. The said extension has been made suf¬ ficiently long to enable the elements 11 to be mounted to rotate with the disk 4 above the spiral structure 13. The said arrangement means that the said elements 11 must be mounted internally via the cone 1 onto the disk already in position. The purpose of the elements 11 is to disrupt hangings of material at the bottom of the cone 1 and to reduce in size possible material accumulations so that t e material can pass through the out-flow opening 8. An essentially cylindrical enclosure can advantageously be mounted onto the outside of the cone 1, the base of the said enclosure extending to the same level as the edge of the mouth opening 1 of the conical vessel. A proportioning disk 4 in accordance with Figure 2 is mounted onto the mouth opening 3 of the bottom part of the cylindrical enclosure 2 so that the disk covers the mouth opening 3 and extends slightly beyond its edges. An operation clearance is required between the bottom edge of the cylindrical enclosure 2 and the stationary propor- tioning disk 4. The proportioning disk 4 is provided with a drive mechan¬ ism by means of which the rotation speed of the disk can be regulated. In this way the device's feeding capacity can be changed by changing the speed of rotation of the disk 4, by using a check plate to adjust the size of the out flow opening 8, or by using the above two measures in combination. In practice, the device has given feed ca- pacities within the range of 15 - 5000 kg/h.

Claims: Patent claims: 1. A device for controlled feeding of particulate ma¬ terial, the said device consisting of a conical out flow part (1) of a vessel containing the material to be fed, a proportioning disk (4) placed underneath the mouth open¬ ing of the out flow part with an operation clearance and rotatable around an axle essentially coaxial with the axis of the out flow part (1) , a flow guiding structure (12) formed at the mouth opening of the out flow part (1) , the flow guiding structure opening spirally in the rotation direction of the proportioning disk (4) and thereby forming an out flow opening (8) , and a doctor blade (5) placed away from the out flow opening (8) in the rotation direction of the disk for the purpose of removing the material from the disk, characterised in that the diameter of the mouth opening of the out flow part (1) is no more than approximately half of the diam¬ eter of the proportioning disk (4) , and that the doctor blade (5) is placed at a distance of at least approxi¬ mately half a rotation downstream of the out flow opening (8) in the rotation direction of the proportioning disk (4). 2. A device as claimed in claim 1, characterised in that the proportioning disk (4) is equipped with loosening elements (11) rotating along with the proportioning disk and extending into the conical out flow part (l) .

Inventors: OERN KAUNO, OERN, KAUNO
Applicants: RAUTE PRECISION OY
Application year: 1993
Main classification: B65D88
IPC codes: B65G65