EP3213812A1

EP3213812A1 - Mixing machine

Info

Publication number: EP3213812A1
Application number: EP17158741.3A
Authority: EP
Inventors: Tommy Bredal
Original assignee: Staring Maskinfabrik AS
Current assignee: Staring Maskinfabrik AS
Priority date: 2016-03-01
Filing date: 2017-03-01
Publication date: 2017-09-06
Also published as: DK179342B1; DK201600132A1

Abstract

Mixing machine, e.g. a compulsory mixer 1, comprising at least one drum 2 equipped with a device for forced mixing of raw materials into a ready product, where the drum has an opening for receiving raw materials and an opening for leading the ready product out of the drum, where at least one of the openings mentioned above is equipped with a safety grate 11 , where the safety grate for inlet and/or outlet is equipped with a device configured to generate oscillating motions 19 in the form of vibrations in order to avoid clogging of the grate by raw materials or ready mixed product.

Description

The present invention relates to a mixing machine as stated in the preamble of claim 1.
The term mixing machine relates e.g. to a compulsory mixer, a countercurrent mixer et al., which is used in the building industry, without limiting the application or the scope of protection of the invention to this.
Mixing machines are characteristic in that they comprise a drum equipped with a device for mixing raw materials into a ready product, where the drum has an opening for receiving raw materials and an opening for leading the ready product out of the drum of the mixing machine.
For explanation of the invention, without limiting the scope of protection of the patent application thereto, compulsory mixers for manufacturing of concrete, wearing surfaces and mortar are used as an example. Concrete, wearing surfaces and mortar are made from regular raw materials, such as sand, gravel, cement, water etc. and are mixed into an appropriate consistence in the mixing machine.
Compulsory mixers for manufacturing of concrete, wearing surfaces and mortar exist in a number of varieties and sizes. Thus, a compulsory mixer can be a stationary installation configured to process large quantities of raw material for the manufacturing of concrete, wearing surfaces or mortar. Further, mobile equipment is known, which enables a practical and demand-controlled manufacturing of concrete or mortar directly at the building site. As an example of such mobile equipment in the form of a compulsory mixer reference is moreover made to DK 2006 00321 U3 to Staring Maskinfabrik A/S.
Necessarily, large forces are required for force mixing the raw materials during the manufacturing of the ready product. For that reason there are also high demands for personal safety in order to prevent persons from getting into contact with the movable parts of the mixing machine.
The authorities thus prescribe that the inlet of the mixing machine, which is configured to receive the raw materials into the drum, must be protected by a grate in order to ensure that persons cannot get into contact with the movable parts. This grate should be constructed in accordance with standard EN 12151:2007.
Further, it is a requirement that the outlet of the mixing machine for leading the ready product out is equipped with a grate which ensures that persons are prevented from getting into contact with the movable parts of the mixing machine. This should likewise be in accordance with EN 12151:2007.
Personal safety at the work place should not be overlooked. However, the compulsory requirements can be a huge disadvantage for the construction workers as the raw materials tend to clog the inlet grate. The problem occurs both on the inlet grate as well as the outlet grate. On the grate for outlet of ready material it is thus necessary continuously to remove accumulating material on and in the grate below the emptying place.
This involves a lot of manual labor and annoyance. Needless to say the problem is bigger when the raw materials contain large rocks, cement or other material, which can harden, set or clump, or in any other way form a layer on the grate below the emptying hatch. The problem can also occur when a more dry or viscid material is mixed, which is not as fluent and is hard to remove. Especially, when mixing fine-grained material where the mixture usually contains less water there is a tendency for the material to clog up the outlet. The source of irritation is so big that the construction workers in frustration will either remove the inlet or outlet grate or make a hole therein after which the mixing machine is no longer legal to use and can potentially cause personal injuries.
Thus, there is a need for providing a solution to the outlined problem i.e. that the inlet and outlet openings of the mixing machine is clogged by raw materials and ready product, respectively, without compromising the high requirements for personal safety.
This is achieved according to the invention by designing the mixing machine as stated in claim 1, where the mixing machine is equipped with a device for generating oscillating motions in the form of vibrations and transferring the vibrations to a safety grate for inlet and/or outlet.
In an embodiment the device is constructed with an active generator which is electrically, hydraulically or mechanically driven and is thus independent of whether or not the mixing machine is in operation and is in the process of mixing.
The term "active" is used for a separate unit, which is not directly connected to or driven by the rotating parts of the mixing machine including the motor. A mechanically driven vibrator can thus be driven by a motor dedicated for that purpose and is independent of the operation of the mixing machine. More specifically, an active generator functions independent of whether or not the mixing machine is in the process of mixing. An active generator can thus be mounted directly onto the inlet or outlet grate or in a different location on the mixing machine, where it is ensured that the vibrations will spread to the grate and have an effect on the grate's ability to shake accumulated material loose.
In an embodiment the device is designed with a passive generator. A passive generator is in an embodiment mechanically driven. The device is thus driven by the movement of the mixing machine and is dependent on whether or not the mixing machine is in operation and in the process of mixing.
In an embodiment an electric vibrator is arranged in connection with the grate in such a manner and with a frequency which is appropriately adjusted such that the vibrator can cause the grate to vibrate. When exposed to the vibration and with gravity as a contributing factor the material will be aided in falling through the grate, thus reducing or completely preventing clogging of the grate.
In another embodiment the device comprises at least one "arm" constructed from a resilient material, hereafter known as resilient element, said resilient element is secured to one end of the grate and extends out from the grate in such a direction that the free end of the resilient element is arranged in an area of the drum of the mixing machine for mixing of materials, where the free end of the resilient element can be met by the mixing machine's device for mixing of raw materials, also called a rotating shovel.
In an embodiment the resilient element, e.g. a piece of spring steel or the like, is thus configured to be deformed in a flexible manner when the device of the mixing machine for mixing raw materials meets the resilient element, and is subsequently released when the device for mixing of raw materials passes by, where the resilient element again will swing back to the starting position during an oscillating vibration-creating movement.
In an embodiment the resilient element is located on the inlet grate and is adapted to, during the meeting with the device for mixing of raw materials, create vibrations in the inlet grate and attempt to shake material loose from the grate.
In a different embodiment the resilient element is located on the outlet grate and is adapted to, during the meeting with the device for mixing of raw materials, create vibrations in the inlet grate and attempt to shake material loose from the grate.
As material only passes through the outlet grate when the contents of the mixing machine is emptied after a mixing has been performed, the outlet is equipped with a closing mechanism, which is configured to prevent material from running out of the mixing machine. In an embodiment the closing mechanism for the outlet is configured to deform the resilient element such that this is forced away from the area where this can be brought into collision with the device for mixing of raw materials. The deformation of the resilient element is of cause not constant, meaning that when the closing mechanism again opens for passage between the drum and the outlet, the resilient element will again assume its original form and position, where this can be brought into collision with the device for mixing of raw materials. In an embodiment the closing mechanism is configured to isolate the resilient element away from the area, in which there is a possibility of collision with the device for mixing of raw materials in that the resilient element is encased in a compartment located in connection with the outlet. The latter can be designated an outlet compartment.
When the resilient arm is referred to as a resilient element it is understood that a resilient element is a unit intended to create vibrations and can assume all possible shapes for an element with a free end, which can be brought into oscillation with consideration for the purpose at hand.
The material for the resilient element can be chosen freely with consideration for the desired spring ability, the ability of the material to absorb vibration energy, which depends on the weight of the unit, and for the wear resistance of the material. Although metal is preferred, resilient elements made from plastic, carbon fibre, ceramic materials, rubber etc. can also be utilized if the design is based on the properties of the given materials. In an embodiment for the resilient element one of the materials metal, plastic, carbon fibre, ceramic or rubber is thus included.
The resilient element is in an embodiment constructed out of at least one piece of resilient flat steel. More specifically it can be a strip-shaped piece of resilient strip iron. The advantage of a flat element is that the vibrations are guided in a certain direction in that the flat element is most easily brought into oscillation perpendicular out from the largest surface. The dimensions of a piece of flat material for use as resilient element, including the ratio between length, width and depth, can thus be used efficiently to design an element with the properties as to frequency and effect which most efficiently creates the vibrations which aids in preventing clogging of the grate by material.
In yet another embodiment the resilient element is constructed of at least one piece of resilient round iron. By using a round material oscillations are allowed in all radially extending directions.
In yet another embodiment the resilient element is designed with a cross section from circular through multangular to triangular.
In yet another embodiment the resilient element is constructed from several separate resilient elements conjoined into a bundle. Thus, a sort of tuning fork is achieved where several resilient elements contribute and interact for creating vibrations. In this way a larger vibration effect is achieved in a simple manner.
In an embodiment the resilient element is designed such that the weight of the material or the cross section thereof increases in the direction departing therefrom towards the end which is secured to the grate. The weight will mean that a larger vibration effect and a longer duration of a vibration cycle before it fades can be achieved. This embodiment should not be perceived as being limiting to the construction of the resilient element. It is thus possible to alter the cross section or increase the weight at a random position on the extent of the resilient element with the purpose of creating vibrations with the desired frequency, duration and energy content with a view to a more effective cleaning of the grate. In yet another embodiment the resilient element is at a random position on the extent of the resilient element equipped with a weight-increasing unit.
In yet another embodiment the mixing machine is constructed with an outlet, which synchronously with the mixing machine's rotation of the shovel, directly or indirectly functions as a device, which is adapted to generate oscillating movement in the form of vibrations. More specifically the mixing machine is equipped with a driving shaft, which is guided through the bottom of the mixing machine drum and directly in connection with the rotating shovel. On the part of the drive shaft, which is arrange outside of the mixing machine drum this is equipped with a wheel with at least one recess, which in a similar manner as a camshaft is in connection with a rod configured to function as a resilient push rod in connections with a safety grate, preferably the outlet grate. As an alternative to the wheel, it can e.g. be the square shaft of the mixing machine which functions as camshaft. The push rod is in an embodiment located in a casing, which retains the push rod in its position relative to the driving shaft with the wheel and the grate, respectively. In an embodiment the push rod is fixed, possibly welded directly to the grate. In another embodiment the grate is resiliently suspended relative to the mixing machine drum and the push rod. In yet another embodiment the push rod is equipped with a spring which retains the push rod in resilient connection in the casing and allows movement of the push rod in the longitudinal direction of the casing.
In yet another embodiment the drive shaft is equipped with one or more protruding transversal rods constructed outside of the drum and under this. The transversal rod is dimensioned such that when it is moved around it will be able to meet the outlet grate or the housing with grate, which constitutes the outlet, and thus be able to shake or vibrate material loose from the grate. In order to avoid accelerated wearing the unit can be mounted resiliently suspended in the mechanical construction. Alternatively, the unit can be constructed from disposable parts which can easily be replaced when these get worn.
In yet another embodiment a resilient element is attached to the outlet grate and constructed and arranged in such a manner that it is brought into mesh with a concentric wheel or a transverse rod when this is moved around.
In the same manner as described above vibrations will arise when the resilient element collides with the counterpart and is later released and exposed to oscillations.
In yet another embodiment, in order to optimize the vibrations in the grate below the emptying place, in the attachment points, i.e. machine bolts, screws or the like, which carries the outlet compartment and/or the outlet grate, a spring device is mounted. The spring device consists in a special embodiment of a bolt with a revolving spring. As the threaded portion is short compared to the length of the bolt, the connection between the mixing chamber and the emptying chamber or safety net in the form of the outlet grate will be resiliently suspended. This results therein that the safety grate - or the safety device, which is mounted on the individual mixing machine, can cause more, and if necessary also stronger, vibrations, which aids the material in running through the safety grate. In a special embodiment the bolt is replaced by a threaded rod of an appropriate length and the head which constitutes a stop for the spring is replaced by a nut. Thus, the resilient effect can be adjusted such that an appropriate resilient suspension of the compartment/the grate can be achieved.
To sum up the mixing machine is equipped with a spring device for resilient suspension of an outlet compartment, and/or a grate for inlet or outlet ensures that the vibrations can spread freely and aid in shaking material loose from grates, which otherwise potentially could clog the grate.
An embodiment for the mixing machine, according to the invention will be described more fully below under reference to the accompanying drawing, in which:

Fig. 1 shows a mixing machine in the form of a compulsory mixer,
fig. 2 shows a cross section through a compulsory mixer,
fig. 3 shows a bottom plate of a compulsory mixer with an opening for the outlet grate with mounted resilient element,
fig. 4 shows the bottom plate with outlet compartment and resilient elements seen from below,
fig. 5 shows an outlet compartment with resilient elements mounted to the grate,
fig. 6 shows a spring mechanism for resilient suspended mounting of an outlet compartment relative to the compulsory mixer,
fig. 7 shows an embodiment where the drive shaft of the compulsory mixer has an outlet for creating vibrations,
fig. 8 shows a detail in connection with transference of vibrations to the outlet compartment, and
fig. 9 shows the suspension of an outlet compartment and provides an overview of the entire construction.

The compulsory mixer 1 shown in fig. 1 shows the drum 2 of the compulsory mixer constructed to receive the raw materials either through a grate, which constitutes the safety lid 3 or through the safety lock 4. The compulsory mixer 1 as shown is mobile and equipped with wheels 5 and a support leg 6, and a tension rod 7. The ready product is let out at the bottom of the drum 2 from an emptying hatch (not shown), and can thus be lead directly into a wheelbarrow, for delivering it to the place where it should be used. The emptying hatch is expediently also equipped with a safety lock 8, which is especially adapted to be mounted thereon.
As shown in Fig. 2 the compulsory mixer is further equipped with a moveable device 9, which handles the mixing of the raw materials and the manufacturing of the ready product. Compared to the compulsory mixer shown in fig. 1 the safety lock 8 is dismantled. Instead an outlet compartment 10 is mounted which includes a safety grate in the form of an outlet grate 11. It is noted that a safety lock 4 is mounted in a recess in safety grate 3 where raw materials can optionally be added through safety lock 4 or through the safety grate 3. In an embodiment (not shown) the safety grate 3 can cover the entire inlet by which the safety lock 4 is not mounted. Instead the safety grate 3 is kept free from accumulating material by means of vibrations according to the present invention.
Fig. 3 shows a bottom plate 12 for a compulsory mixer 1 with an opening 13 for insertion of an outlet compartment 14, where the outlet grate 11 with resilient elements 15 is attached. A displaceable closing mechanism constitutes an emptying hatch 16. The emptying hatch 16 can thus retain the materials which are being mixed in drum 2 for mixing of raw materials until the mixture has achieved the desired structure and homogeneity. It is noted that the resilient elements 15 rise up through bottom plate 12 when the emptying hatch 16 is open. In part material runs out from the mixing drum 2 to the outlet compartment 14, and partly the resilient elements 15 bring themselves in position for collision with the movable device 9, which constitutes a rotating shovel for mixing of material in the drum 2 for mixing of material. In the collision, which occurs when the moveable device 9 meets the resilient elements 15, these are temporarily deformed and when the movable device passes by the resilient elements 15 they are released again, which leaves these to an oscillating motion, which creates vibrations in the outlet grate 11 to which the resilient element 15 are secured at one end, where the other end, as can be seen, is suspended in a free floating manner.
Fig. 4 shows a bottom plate 12 seen from the other side. Thus, it can be seen more clearly where the outlet grate 11 is mounted to the bottom of the outlet compartment 14. Further, a dividing plate 17 is inserted in the compartment 14. Thus, a better rigidity of the compartment 14 is achieved. The compartment 14 is further equipped with tongues 18 by which compartment 14 can be mounted on the bottom plate 12 by means of a spring device 19. A detailed drawing, fig. 5, shows the outlet compartment 14 in more detail with resilient elements 15 mounted to the outlet grate 11. Fig. 6 further shows the spring device 19 for resilient suspended mounting of the outlet compartment 14 on the bottom plate 12 of the compulsory mixer 1. In detail the spring device 19 constitutes a machine bolt 20 with a head 21, which forms a stop for the travel of the spring 24, a body 22 and a threaded portion 23, said threaded portion 23 is configured to constitute the counterpart to a threaded hole on the bottom plate 12 (not shown). A spring 24 is mounted in the spring device 19 and thus constitutes the resilient suspension for the outlet compartment 14 in relation to the bottom plate 12. When the resilient elements 15 are manipulated it is thus possible to vibrate the entire compartment with the grate 11 in the resilient suspension with the spring device 19, by which material running out is prevented from clogging the outlet grate 11 with the resulting inconveniences.
The figures 7 to 9 show an alternative embodiment where the compulsory mixer 1 on its drive shaft during the lead through in the drum 2 of the compulsory mixer is equipped with an outlet where a rotating rod or a push rod 25 can create vibrations for preventing clogging of material on the outlet grate 11. Notice also the spring device 19 for mounting of the outlet compartment 14, which in this version is constructed from a threaded rod with a spring and a washer and bolt, which enables adjustment of the properties of the resilient suspension.

Claims

Mixing machine, e.g. a compulsory mixer, comprising at least one drum equipped with a device for force mixing of raw materials into a ready product, where the drum has an opening for receiving raw materials and an opening in the form of an outlet for leading the ready product out of the drum, where at least one of the openings mentioned above is equipped with a safety grate,
characterized in
that the mixing machine is equipped with a device configured to generate oscillating motions in the form of vibrations and to transfer the vibrations to a safety grate for inlet and/or outlet.
Mixing machine according to claim 1
c h a r a c t e r i z e d in
that the device configured to generate oscillating motions in the form of vibrations is an active generator, which is electrically, hydraulically of mechanically driven and is independent of whether or not the mixing machine is in operation and is in the process of mixing.
Mixing machine according to claim 1
characterized in
that the device configured to generate oscillating motions in the form of vibrations is a passive generator driven by the motion of the mixing machine and is dependent on whether or not the mixing machine is in operation and is in the process of mixing.
Mixing machine according to claim 3
characterized in
that the device configured to generate oscillating motions in the form of vibrations comprises at least one resilient element, said resilient element is secured at one end to the grate and extends out from the grate in such a direction that the free end of the resilient element is arranged in an area of the mixing machine's drum for mixing of materials where the free end of the resilient element can be met by the mixing machine's device for mixing of raw materials.
Mixing machine according to claim 4
characterized in
that the resilient element is configured to be deformed in a flexible manner when the mixing machine's device for mixing of raw materials meets the resilient element, and subsequently is released when the device for mixing of raw materials passes by, and then again will swing back to the starting position during an oscillating vibration-creating movement.
Mixing machine according to claim 5
characterized in
that the resilient element is located on the inlet grate and is adapted to, during the meeting with the device for mixing of raw materials, create vibrations in the inlet grate and attempt to shake material loose from the grate.
Mixing machine according to claim 5
characterized in
that the resilient element is located on the outlet grate and is adapted to, during the meeting with the device for mixing of raw materials, create vibrations in the inlet grate and attempt to shake material loose from the grate.
Mixing machine according to claim 5
characterized in
that the outlet is equipped with a closing mechanism configured to prevent the material from running out of the mixing machine, and is further configured to isolate the resilient element away from collision with the device for mixing of raw materials in that the resilient element is encased in the outlet compartment.
Mixing machine according to claim 5
characterized in
that the resilient element contains one of the materials metal, plastics, carbon fibre, ceramic or rubber.
Mixing machine according to claim 5
characterized in
that the resilient element is constructed out of at least one piece of resilient flat steel or round steel, where the cross section of the round steel can be from circular through multangular to triangular.
Mixing machine according to claim 5
characterized in
that the resilient element is designed such that the weight of the material or the cross section thereof increases in the direction departing therefrom towards the end secured to the grate, or at a random position of the extent of the resilient element is equipped with a weight-increasing unit.
Mixing machine according to one of the claims 5 to 11
characterized in
that the resulting resilient element is constructed from several separate resilient elements conjoined into a bundle.
Mixing machine according to one of the claims 1 to 12
characterized in
that the mixing machine is furnished with an outlet, which synchronously with the mixing machine's rotation of the shovel, directly or indirectly functions as a device configured to generate oscillating motions in the form of vibrations.
Mixing machine according to one of the claims 13
characterized in
that the mixing machine is equipped with a drive shaft, which is guided thought the bottom of the drum of the mixing machine and directly in connection with the rotating shovel, and on the part of the drive shaft which is located outside of the drum of the mixing machine, is equipped with a wheel with at least one recess, which in a similar manner as a camshaft is in connection with a rod intended to function as a resilient push rod in connection with the safety grate, preferably the outlet grate.
Mixing machine according to one of the claims 1 to 14
characterized in
that the mixing machine is equipped with a spring mechanism for resilient suspended mounting of an outlet compartment and/or a spring mechanism for resilient suspended mounting of an inlet or outlet grate.