Sanding device and method for preforms

Abstract

The invention describes a device for applying sand to preforms for wetting and sanding bricks prior to firing (preforms), in order to prevent sticking of the stacked bricks in the firing oven. The device consists of a sanding device in which the preforms are placed in order to wet and sand the contact surfaces in a targeted manner. In one embodiment, the sanding device consists of a liquid pan and a sanding pan for first wetting and then sanding the contact surfaces of the preforms. By means of the targeted and sustainable application of sand on a surface of preforms, it is ensured that sufficient sand is applied between the preforms as an intermediate layer in the firing oven, and scatter losses commonly caused by prior art sprinkling with sand from above. The device according to the invention not only saves sand, but also protects other system parts which are not designed to handle scattered sand. Also, the device according to the invention reduces dust generation during the sanding of preforms.

Claims

1. A device for applying sand to preforms, comprising a sanding device for applying sand to the preforms, wherein the sanding device comprises a sanding pan which is filled at least partially with a fine-grained and heat-resistant material; and a transferring device for placing the preforms into the sanding device in order to apply sand to the contact surfaces of the preforms and to remove the sanded preforms from the sanding device.

2. The device according to claim 1, the sanding device further comprising a liquid pan for wetting the preforms.

3. The device according to claim 1, the sanding pan filled with a mixture of fine-grained and heat-resistant material and a liquid, and the transferring device adapted to place the preforms onto the surface of the mixture in order to substantially simultaneously wet and sand the contact surface of the preforms.

4. The device according to claim 2, the liquid pan filled with a liquid and comprising a support for holding preforms which is adapted to wet the contact surface of the preforms, and the transferring device adapted to first place the preforms onto the support, then to grasp the preforms and transfer them with the wetted contact surface to the sanding pan.

5. The device according to claim 4, the support comprising a wetting material which can hold the liquid at the positions where the preforms are placed.

6. The device according to claim 5, the support at least partially liquid-permeable in the liquid in the liquid pan and raisable and lowered in the liquid pan in order for the wetting material to become soaked with the liquid.

7. The device according to claim 4, the support is at least partially a grille.

8. The device according to claim 5, the wetting material having an outline which at most is equal to the contact surface of the preforms in order to avoid wetting the visible side surfaces of the preforms.

9. The device according to claim 8, the outline of the wetting material adapted such that only parts of the contact surface are wetted so that only these parts of the contact surface are sanded.

10. The device according to claim 5, the wetting material made of sponge, felt or another absorbing or adsorbing material.

11. The device according to claim 3, the liquid having at least one of a viscosity or surface tension which is suitable for soaking the wetting material and for wetting the contact surface of the preforms; or the liquid including water, wallpaper paste, oil, glue or another liquid which enables an adhesion of the fine, rained and heat-resistant material from the sanding pan onto the preforms.

12. (canceled)

13. The device according to claim 2, the liquid pan filled with a liquid and comprising at least one roll for accommodating preforms, wherein the at least one roll wets the contact surface of the preforms by making a rolling motion, that the transferring device adapted to guide the contact surface of the preforms over the at least one roll in a kinematic link to the rolling motion and to transfer the preforms with the wetted contact area into the sanding pan.

14. The device according to claim 13, the at least one roll is located in the liquid.

15. The device according to claim 13, the liquid pan further comprising rolls located in the liquid and coupled to one of the at least one rolls, respectively, in a kinematic link so as to wet the at least one roll by means of the rolling motion.

16. The device according to claim 13, the rolls including a sponge-like material or another absorbing or adsorbing material.

17. The device according to claim 2, the liquid pan comprising upwardly-directed nozzles (61) for spraying the contact area of the preforms with a liquid the transferring device adapted to hold the contact surface of the preforms above the nozzles and to transfer the preforms with the wetted contact surface into the sanding pan.

18. The device according to claim 1, the sanding pan comprising a shaking mechanism to smooth the fine-grained and heat-resistant material.

19. The device according to claim 1, the sanding device comprising a rake or doctor blade which can move in the sanding pan to smooth over the surface of the at least partially fine-grained and heat-resistant material and to remove clumps in the at least fine-grained and heat-resistant material.

20. The device according to claim 1, the transferring device is also adapted to remove the preforms from a feeding device prior to placement in the sanding device and to place the preforms onto a firing cart after removal from the sanding device.

21. A method for applying sand to preforms, the method comprising; placing the preforms onto the surface of a partially fine-grained and heat-resistant material located in a sanding pan of sanding device in order to sand the contact surface of the preforms.

Description

[0042] The present invention is described in detail below with reference to the attached drawings.

[0043] FIG. 1 shows a view of a device for sanding preforms according to the prior art.

[0044] FIG. 2 shows the device according to the invention for sanding preforms, comprising a liquid pan and sanding device.

[0045] FIG. 3 shows a detailed sketch of an embodiment of the liquid pan according to the invention with a support and wetting material.

[0046] FIG. 4 shows a detailed sketch of an embodiment of the sanding pan according to the invention in a side view.

[0047] FIG. 5 shows a detailed sketch of an embodiment of the liquid pan according to the invention with wetting rolls.

[0048] FIG. 6 shows a detailed sketch of an embodiment of the liquid pan according to the invention with spray nozzles for wetting the preforms.

[0049] FIG. 7 shows a detailed sketch of an embodiment of the sanding pan according to the invention and filling with a sand-liquid mixture in a side view.

[0050] FIG. 8 shows a top view of an embodiment of the device according to the invention for sanding preforms in the context of a system for manufacturing bricks.

[0051] FIG. 1 shows a sanding system according to the prior art. The sand is scattered onto the preforms from above here. For this purpose, in this system example the sand is fed to collection receivers 11 by way of feed lines 10, the receivers narrowing downward and feeding the sand to a cylindrical drum 12 which is attached lateral to the brick feeder. A brush 13 which is suspended in the drum rotatably about the longitudinal direction of the drum is caused to rotate by means of a drive mechanism, then takes up the sand and distributes it as evenly as possible over the length of a slotted opening located at the lower end of the drum. From there, the sand trickles by gravity onto the work piece to be sanded located on a conveyor belt 14 or another conveying device for this purpose.

[0052] FIG. 2 shows an embodiment of the device 20 according to the invention for sanding preforms. The device 20 consists of a liquid pan 21 and a sanding pan 29, wherein both pans are suitable for holding preforms 22. The liquid pan 21 is at least partially filled with a liquid 54 (see FIG. 5) and the sanding pan 29 is at least partially filled with heat-resistant and fine-grained material 28 (such as sand, see FIG. 4). In one embodiment, the liquid- and/or sanding pan are located on height-adjustable support tables 210 and 211, respectively, which can be fixed to the system base so that a suitable height level of the upper edges of the liquid and/or sanding pan can be established. For example, it can be desirable for the sanding pan 29 and/or the liquid pan 21 to be adjusted with respect to positional height of the preforms to an existing height level of a manufacturing facility for processing preforms.

[0053] A support 23 for holding the preforms 22 is provided for the liquid pan 21, wherein the outer dimensions of the support 23 are such that it fits into the liquid pan 21. In the process, it must be noted that the support 23 is designed as a grille so that dipping into the liquid can be easily done. Other embodiments are conceivable for the support which ensure sufficient support strength, torsional stiffness and permeability for liquids. Moreover, FIGS. 2 and 3 show that support 23 can be raised and lowered in the liquid pan 21 using vertical pistons 24 in the liquid pan.

[0054] Of course, the invention can also be operated using other lifting devices.

[0055] The purpose of lowering and raising the support 23 is to soak the wetting material 31 located at the positions of the placed preforms 22 with liquid from the liquid pan 21. After a series of wetting cycles, the support 23 is lowered into the liquid in order to again soak the wetting material 31, which consists of pads in one embodiment, with sufficient liquid.

[0056] For the sanding pan 29 of the sanding device 20, an at least partial filling with sand 28 or another heat-resistant and fine-grained material is provided. In this sense, sand in the description text is intended to mean any fine-grained and heat-resistant substance which serves the purpose of the invention of suitably sanding the preforms prior to firing so as to avoid sticking of the preforms and firing of the fine-grained intermediate layer in the firing oven.

[0057] After the preforms 22 are wetted in the liquid pan 21, using a transferring device 51 they are placed into the sanding pan 29 with the wetted contact area 53 facing downward. Simply by virtue of the contact pressure of the preforms alone in the sanding pan 29, the contact areas of the preforms 22 are coated with sand and can then be removed by the same or by another transferring device and placed in a suitable preparation area for further handling (e.g. firing).

[0058] FIG. 3 shows an embodiment of the liquid pan 21 without any preforms placed therein. Shown are areas 31 on the support which can be designed as absorbent pads and designed as wetting material at the positions of the preforms.

[0059] Alternatively, it is also conceivable that the wetting material 31 is a component of the otherwise grille-like support 23 in that the wetting material is embedded in the support structure 23 as pad-like surfaces. What is critical to the execution of the invention is that the material properties, geometry and output of the wetting material 31 at or in the support is designed such that the contact area of the preforms on the support is wetted in a desired form and with a sufficient amount of liquid from the liquid pan 21.

[0060] In the embodiment shown, the size of the wetting surfaces 31 or pads is large enough to wet the contact areas of entire groups of preforms.

[0061] However, in another embodiment, it is also conceivable that the wetting surfaces are further subdivided in order to only accommodate at least one preform.

[0062] With regard to the material properties of the wetting material 31, sponge- or felt-like materials are advantageous, wherein other absorbable or adsorbable materials can of course also be used.

[0063] With regard to the geometry of the wetting material 31, in one embodiment it is provided that the wetting material has an outline which is encompassed by the contact area of a preform in order to prevent wetting of the visible side surfaces of the preforms. In this case, the wetting material disappears in the top view below the outline of the placed preform. With regard to this basic geometry, other conceivable outlines of the wetting material are those in which only parts of the contact area are wetted, for example only an outer edge of the contact area. But it is also conceivable that the outlines of the wetting material extend beyond the outline of a placed preform in order to wet a plurality of preforms using a pad 31.

[0064] In order to repeatedly soak the wetting material 31 with liquid after a few wetting passes, the support 23 is lowered into the liquid pan 32 of liquid pan 21 without any preforms in the support until the wetting material 31 is dipped into the liquid. For this purpose, liquids such as water, wallpaper paste, oil or glue can be used. In this regard, it is within the scope of expert actions to select a liquid whose properties are such as to sufficiently soak the wetting material 31 on the one hand and on the other hand to well wet the contact area of the preforms. Moreover, a liquid must be selected which facilitates adhesion of the fine-grained and heat-resistant material to the preform.

[0065] FIG. 4 shows a detailed schema of an embodiment of the sanding pan 29 according to the invention in a side view. The same reference signs in the figures refer to the same elements of the invention in FIGS. 2 and 3. In this embodiment, the sanding pan 29 comprises a shaking mechanism 41 and a rake device 25 for flattening the sand filling 28 and to remove clumps. In order to achieve an even sanding, a sufficiently smooth and homogeneous sand surface is required. To this end, in this embodiment the sanding pan 29 comprises a pair of conveyor belts 26 at the right and left side walls, respectively, the ends 25a and 25b of the rake 25 being attached at said side walls. A suitable motor 27 drives the conveyor belts 26a and 26b using drive rolls and pulleys, which are advantageously connected in pairs to an axle, the motor pulling the rake 25 across the sand surface to remove clumps from the sand and homogenizing the sand. For the purposes of removing clumps from the sand pan 29, other devices such as skirts or doctor blades are conceivable which are pulled over the sand surface.

[0066] With regard to smoothing the sand surface, a shaking mechanism is provided in this embodiment which sporadically shakes the sanding pan 29 in order to smooth the sand surface. To this end, an embodiment is provided for connecting the sanding pan 29 in positively-locking fashion to a shaking table 42 which in turn is connected to a shaking motor 41 but which is decoupled from the support table 210 by way of a suitable suspension and damping.

[0067] In another embodiment, it is further conceivable to use the shaking mechanism to also remove clumps in the sand. Suitable shaking not only leads to smoothing of the sand surface, but also to clumps of fine sand being removed and floating to the top. It can be advantageous to keep the length of the rake teeth short since the sand filling then only has to be raked through on the surface.

[0068] FIG. 5 shows a detailed sketch of an embodiment of the liquid pan 21 according to the invention with rolls 51 and 52. Instead of wetting pads, in this embodiment wetting rolls are used which have sponge-like surfaces, the rollsby way of a friction-lock connecting to the bottom sides 53 of the preformscause a wetting of the contact areas of the preforms, the areas then being placed into the sanding pan 29. In the embodiment shown, the bottom sides 53 and the rolls 51 and 52 are coupled together under friction so that the direction of motion of the preforms under friction with the upper wetting roll 51 leads to a rotation of the wetting roll 51 which in turn brings about a rotation of another liquid roll 52 dipped in the liquid. In this way, a push or pull movement of the preforms which is executed by a transferring device leads to a sustained wetting of the contact areas of the preforms since the wetting material or the sponge-like surface of the wetting roll 51 is kept wet by the sponge-like surface of liquid roll 52 as long as the preform is pushed, pulled or led over the surface of the wetting roll. Of course, embodiments are conceivable in which multiple wetting and liquid roll pairs are used in order to improve the wetting of the preforms, for example. In an alternate embodiment, only rolls are used, all of which rotate in the liquid.

[0069] Another alternate embodiment for a liquid pan is shown in FIG. 6 in which the use of a spray device for wetting the contact areas of the preforms is shown. In this embodiment, the liquid basin functions as a collection basin for receiving the descending spray fog and excess liquid dripping from the bottom side of the preforms. It is not necessary to fill the liquid basin since the liquid is introduced to outlet openings 61 by way of feed lines 63 at a pressure sufficient enough to exit upward from there and to wet the contact areas of the preforms with liquid. The embodiment shown involves liquid nozzles 61 which create a spray fog and thereby ensure an even and sparse wetting of the bottom sides 53 of the preforms. In another embodiment, a collection bowl 62 placed above the pan accommodates the descending spray fog or liquid excess and routes the same to liquid pan 21.

[0070] In all embodiments of the liquid basin, it is conceivable that the liquid pan 21 is located on support tables 211 which are height-adjustable and fixable to the system base in order, as already described, to adjust a suitable height level of the upper edges of the liquid pan relative to the rest of the sanding system as shown in FIG. 8.

[0071] The sanding of the preforms 22 according to the invention is also achievable by performing the wetting and sanding in a single work step. From the position of the device, this idea is realizable in an embodiment shown in FIG. 7. In order to carry out the sanding of the preforms in a single work step, the sanding pan 29 is filled with a liquid-sand mixture onto which the preforms are placed by the transferring device 51. In this embodiment, therefore, there is no need for a liquid pan 21.

[0072] It is advantageous for the liquid-sand mixture 72 to consist of a mixture of sand, oil and paste. However, in order to achieve a satisfactory wetting of the preforms with the liquid-sand mixture, many material combinations and mixture ratios are conceivable. Also, the liquid itself is in turn conceivable as a homogeneous or a heterogeneous mixture.

[0073] As in the embodiment already shown in FIG. 4, a shaking mechanism 41 is also conceivable in this embodiment of a sanding pan 29, as well as a rake device 71 or doctor blade device 71 for smoothing the liquid-sand mixture 72 and to remove clumps. It is advantageous for this embodiment to comprise a doctor blade 71 instead of a rake if the toughness or heterogeneity of the liquid-sand mixture does not allow for raking. Here, the doctor blade 71 comprises a sufficiently stiff lip which can be pulled over the liquid-sand mixture 72 in order to strip away clumps. If the properties of the liquid-sand mixture 72 allow it, it is also conceivable to use the doctor blade to smooth the mixture surface. In this case, then, there is no need for a shaking mechanism 41.

[0074] FIG. 8 shows a possible system overview, with transferring devices 51 in a top view in which the device according to the invention can be used for sanding preforms. In this embodiment, the transferring device 51 is shown as a pair of transfer robots, but any other device suitable for transferring preforms from a liquid pan 21 with identical contact surfaces to a sanding device 29 is conceivable as an embodiment. Furthermore, in this embodiment the transferring devices 51 are designed to remove the preforms from a feeder prior to insertion into the liquid pan and after removal from the sanding device to feed the bricks to a firing cart. For this purpose, the transfer robot 51 removes the preforms from a preparation line 52 and places them in a preparation area 53 or onto a firing cart 53 after sanding according to the invention.

[0075] In summary, the invention discloses a device 20 for sanding preforms, the device wetting and sanding the bricks 22. The preforms are held by a support 23 sufficiently long over the liquid surface of a liquid pan 21 for the contact areas to be wetted with the liquid from the soaked wetting pads 31. Then, the preforms are placed in a sanding device 29 using a suitable transferring device 51 having the same contact area so that the contact areas of the preforms previously wetted can now be coated with sand.

[0076] By applying sand to a surface of preforms in a targeted and sustainable manner, the application of a sufficient intermediate layer of sand between the preforms in the firing oven is ensured and the scatter losses in the rest of the system for manufacturing bricks are avoided. This saves sand and as much as possible protects other system parts which are not designed to handle scattered sand. Also, a considerable reduction in dust generation can be expected.