GUSTAVSSON HANS (SE)
| GB2318304A | 1998-04-22 | |||
| IE77873B1 | 1998-01-14 | |||
| US5795060A | 1998-08-18 | |||
| DE2417012A1 | 1975-10-23 | |||
| US4697960A | 1987-10-06 |
| 1. | Method for automatic mixing of water and concrete for rock bolting including adding water and concrete to a mixing vessel (1), mixing the water and concrete, and transferring the water and concrete to a drill hole (2), characterized by calculating amount of water and amount of concrete for the mixture of water and concrete is in a control unit (3), adding the calculated amount of water to the mixing vessel (1), weighing (4) real added amount of water, correcting the calculated amount of concrete considering the real added amount of water to obtain a correct mixture of water and concrete, mixing concrete and water during a predetermined time, and transferring the mixture of water and concrete is to a drill hole (2). |
| 2. | Method according to claim 1, characterized by filling the mixing vessel (1) with water, after the transferring of the water and concrete mixture to a drill hole (2), the control unit (3) controlling the water level (5) in the mixing vessel (1) between an upper level and a lower level and repeating the control for a predetermined time. |
| 3. | Arrangement for automatic mixing of water and concrete for rock bolting including means (11) for adding water to a mixing vessel (1), and means (12) for adding concrete to the mixing vessel (1), a mixer (13) for mixing the water and concrete in the mixing vessel (1), and means (14) for transferring the water and concrete to a drill hole (2), characterized in a control unit (3) for calculating amount of water and amount of concrete for the mixture of water and concrete, means (11) for adding the calculated amount of water to the mixing vessel (1), means (4) for weighing real added amount of water, means in the control unit (3) for correcting the amount of concrete considering the real added amount of water to obtain a correct mixture of water and concrete, means in the control unit for controlling the time for the mixing, and means (14) for transferring the water and concrete mixture to a drill hole (2). |
| 4. | Arrangement according to claim 3, characterized in means (11) for filling of the mixing vessel (1) with water after the transferring of the water and concrete mixture to a drill hole (2), and means in the control unit (3) for controlling the water level (5) in the mixing vessel (1) between an upper level and a lower level for a predetermined time. |
The present invention relates to a method and an arrangement for automatic mixing of water and concrete for rock bolting.
In the mixing of water and concrete for rock bolting it is customary to add measured volumes of water and concrete to a mixing vessel. Thereafter concrete and water are mixed until the mixture seems ready. A disadvantage with this method is that you get an admixture of air, which means that the mixing proportion between water and concrete becomes uncertain. This leads to that the fastening of the rock bolt in the rock may be somewhat uncertain, i.e. more rock bolts may be needed for the reinforcement of the rock than would be needed if the mixture of water and concrete had a more secure mixing proportion between water and concrete.
The present invention, which is defined in the following patent claims, has the purpose to achieve an automatic method and arrangement for mixing of water and concrete that guarantees an accurate mixing proportion between water and concrete without negative influence from air admixture.
An embodiment of the invention is described below with reference to enclosed figure, which shows schematically an arrangement for automatic mixing of water and concrete according to the invention.
The arrangement disclosed in the figure includes a mixing vessel 1 in which a mixing arrangement in the form of a mixer 13 is arranged. The mixer is run by a motor 15, which running is controlled by a control unit 3. For determination of the amount of material in the mixing vessel 1, this is arranged for weighing with a scale 4. Water is added to the mixing vessel 1 from a water source 16 via a valve 11 and a pipe 17. Concrete is added to the mixing vessel 1 from a supply 18 via a feeder 12 and a pipe 19. The valve 11 and the feeder 12 are controlled by the control unit 3. The arrangement shown on the figure works in the following way. First the operator sets the demanded weight ratio between concrete and water and the demanded total weight for the mixture unless the whole volume of the mixing vessel is demanded. These values are stored in the control unit 3. The control unit 3 then calculates the demanded weights of concrete and water from either the demanded weight of the completed mixture or from the volume of the mixing vessel 1. The mixing starts by weighing the amounts of water and concrete with the scale 4. In the shown example the mixing vessel 1 is standing on the scale 4. The mixing vessel may of course be hung up, e.g. in a load cell. The water is added quickly from the source 16 to about the wished amount. Thereafter, the amount of concrete is recalculated to take into account the real amount of water. The concrete is added to the mixing vessel 1 with the feeder 12, e.g. a screw feeder. Thereafter the motor 15 is started to run the mixer 13 a predetermined time set in the control unit 3. When the mixing has been made, the mixture of water and concrete is transferred to the drill hole 2 with the pump 14.
When the mixture of water and concrete has been transferred to the drill hole 2, the mixing vessel 1 and other equipment should be cleaned to prevent that the equipment is destroyed at an interruption of the work. This is made by adding water to the mixing vessel 1 until the water level 5 reaches an upper, selectable limit. The mixer 13 and the pump 14 are run during the whole cleaning procedure. The water level 5 is determined with the help of the scale 4. When the water level 5 has reached a lower limit, then the mixing vessel is refilled to the upper level. This method is repeated a predetermined number of times or during a predetermined time. When the cleaning is carried through the equipment is switched off and the mixing vessel 1 is emptied. The whole process is controlled by the control unit 3. An advantage with this method is that it is automatic so that the operator can leave the equipment and perform other work at the same time as the cleaning is performed.