Abstract
The invention relates to a method for the decoating at least in part of blanks made of metal which are coated on one or both sides in regions, which have a main extension direction, wherein the regions to be decoated can extend in both a straight or curved manner in the main extension direction. The invention further relates to a device for the decoating at least in part of a coated blank in order to carry out the method according to the invention. A method is provided in which the blank is placed on a blank support of a press and during the closing movement of the press at least one scraping knife preferably completely removes the coating of the blank by scraping substantially perpendicular to the main extension direction of the region of the blank to be decoated.
Claims
1. A method for the decoating at least in part of blanks made of metal which are coated on one or both sides in regions, which are flat and have a main extension direction in a plane of the blank, wherein the regions to be decoated extend in either a straight or curved manner in the main extension direction, the method comprising: providing a blank and placing the blank on a blank support of a press and wherein said press has upper and lower tools, the blank support, a pressing table, and at least one scraping knife mounted on at least one of the upper and lower tools, lowering the upper tool and simultaneously moving said at least one scraping knife to remove the coating on the blank by scraping substantially perpendicular to the main extension direction of the region of the blank to be decoated and within the plane of the blank.
2. A method according to claim 1, wherein the decoating is carried out to provide a welded region, in particular a welded seam region.
3. A method according to claim 1, wherein the blank is decoated on the edge regions.
4. A method according to claim 1, wherein the decoating is carried out on both sides in one work step.
5. A method according to claim 1, wherein the blank which is decoated at least in part is provided for hot forming.
6. A method according to claim 1, wherein a cut is made following the decoating at least in part of the blank.
7. A method according to claim 6, wherein the cut is carried out during the lowering of the upper tool.
8. A method according to claim 1, wherein the at least one scraping knife is actively driven by driving means or forcibly actuated to carry out the decoating process.
9. A method according to claim 1, wherein the regions of the blank to be decoated have a width of 0.2 mm to 5 mm, preferably a width of 0.8 mm to 1.4 mm.
10. A device for the decoating at least in part of a coated blank, comprising a press with an upper tool, a lower tool, a blank support, a pressing table, at least one scraping knife and means to move the at least one scraping knife substantially perpendicular to a main extension direction of a region of the blank to be decoated in order to decoat this region, wherein the means to move the at least one scraping knife comprises forcible scraping knife guides to guide the at least one scraping knife or a plurality of scraping knives, and wherein at least one scraping knife in the upper tool and at least one scraping knife in the lower tool and forcible scraping knife guides allocated to each scraping knife are provided, the forcible scraping knife guides of the upper tool are form locked to the forcible scraping knife guides of the lower tool during a welding process of the press and the forcible scraping knife guides of the lower tool are forcibly actuated by means of sleeves of the press which have thrust chamfers such that by means of a closing movement of the press the scraping knives in the upper tool and in the lower tool are displaced perpendicular to the closing movement.
Description
BRIEF DESCRIPTION OF THE INVENTION
(1) The invention shall be described in greater detail below using exemplary embodiments in combination with the figures, in which:
(2) FIG. 1 is a schematic sectional view of a first exemplary embodiment of a device according to the invention for the decoating at least in part of a coated blankdecoat,
(3) FIG. 2 is a detailed view of the scraping knife guide of the exemplary embodiment represented in FIG. 1,
(4) FIG. 3 is a detailed view of the scraping knife and the blank of the exemplary embodiment represented in FIG. 1,
(5) FIG. 4 is a schematic sectional view of the exemplary embodiment represented in FIG. 1 with the upper and lower tools closed,
(6) FIG. 5 is a detailed view of the scraping knife guide represented in FIG. 4,
(7) FIG. 6 is a detailed view of the scraping knife represented in FIG. 5,
(8) FIG. 7 is a schematic sectional view of the exemplary embodiment represented in FIG. 1 following decoating of the blank,
(9) FIG. 8 is a detailed view of the scraping knife guide represented in FIG. 7,
(10) FIG. 9 is a detailed view of the scraping knife and the decoated region of the blank represented in FIG. 8,
(11) FIG. 10 is a top view of a blank and the regions to be decoated,
(12) FIG. 11 is a schematic sectional view of a second exemplary embodiment of a device according to the invention for decoating and cutting a blank when open,
(13) FIG. 12 is the exemplary embodiment represented in FIG. 11 with the upper and lower tools closed,
(14) FIG. 13 is a detailed view of the position of the scraping knife represented in FIG. 12,
(15) FIG. 14 shows the exemplary embodiment represented in FIG. 11 after decoating and before cutting of the blank,
(16) FIG. 15 is a detailed view of the scraping knife represented in FIG. 14 in the region of the decoated blank,
(17) FIG. 16 shows the exemplary embodiment represented in FIG. 11 after cutting of the blank,
(18) FIG. 17 is a detailed view of the cutting edges and the scraping knife guide of the exemplary embodiment represented in FIG. 11 and
(19) FIG. 18 is a detailed view of the decoated blank immediately after cutting of the blank in the cutting region.
DETAILED DESCRIPTION OF THE INVENTION
(20) FIG. 1 shows a first exemplary embodiment of a press 1 for decoating a blank 5 having an upper tool 2, a lower tool 3, a blank support 4, a press stamp 6a and a pressing table 6b. The blank support 4 is arranged in the lower tool 3. In the upper tool 2, a counterholder 4a is provided opposite the blank support 4 to impact the blank 5 with a retention force. Each two scraping knife guides 11, 14 and 12 and 13, which guide the scraping knives 7, 8, 9 and 10, are arranged in pairs and mirror-symmetric to one another in the upper and lower tools 2, 3. The scraping knife guides 11, 12, 13 and 14 are impacted with a force by means of compression springs 20 such that the scraping knife guides press against the blank supports and are held in the scraping position.
(21) FIG. 1 further shows sleeves 16 of press 1 which have thrust chamfers 15 at their ends which are used to forcibly actuate the scraping knife guides 11, 14. In order for the scraping knife guides 12, 13 of the upper tool 2 to also be forcibly actuated synchronously to the scraping knife guides 11, 14 of the lower tool 3, said scraping knife guides have protruding regions 21a which penetrate into recesses 21b of the scraping knife guides 11, 14 when the upper and lower tools 2, 3 are closed. In this case, scraping knife guides 11 and 12 and 14 and 13 are form-locked to one another.
(22) A detailed view of the scraping knife guide 14 and the scraping knife 10 and the blank 5 in the exemplary embodiment represented in FIG. 1 is shown in FIG. 2. It should be noted that the blank 5 lies on the scraping knife 10. This is better demonstrated in FIG. 3. From this figure, it is possible to recognise that preferably curved scraping knives 10 are used in the exemplary embodiment shown. The width of the region to be decoated is approximately 1.2 mm in the present embodiment. In order to achieve a good result when decoating, it has been shown that it is advantageous if the scraping knife has a projection b of at least 0.04 mm.
(23) FIG. 4 shows the exemplary embodiment from FIG. 1 schematically in a sectional view at the point at which the upper tool 2 is retracted into the lower tool 3. The scraping knife guides 12, 13 are then coupled to the scraping knife guides 11 and 14 in a form lock. The scraping knife guides 11, 12, 13, 14 and therefore also the scraping knives 7, 8, 9, 10 are held in position by the compression springs 20 such that no lateral movement of the scraping knives 7, 8, 9, 10 occurs. The blank support 4 is pressed against the blank 5 by the pressure of the press stamp 6a and the scraping knives are inserted into the coating 5b (see FIG. 6) of the blank to be decoated with their cutting edges. The position of the scraping knives 9, 10 when the upper and lower tools 2, 3 are closed is shown in FIG. 5. In the exemplary embodiment shown, decoating on both sides can take place as the scraping knives 9, 10 touch both the upper face and the lower face of the blank 5. This is shown in an even clearer manner in FIG. 6, which shows the region of the intrusion of the scraping knives 9, 10 into the blank 5 to be decoated. When the upper and lower tools 2, 3 are closed, the scraping knives, 9, 10 penetrate the blank 5, in particular the coating thereof.
(24) The sleeves 16 are then moved out of the press or the pressing table 6b is lowered relative to the sleeves. As a result, the sleeves 16 forcibly displace the scraping knife guides 11, 14 of the lower tool outwards by means of their thrust chamfers 15 and the scraping knives 7, 10 decoat the region of the blank to be decoated transverse to the main extension direction thereof. Due to the form lock between the scraping knife guides 11, 14 of the lower tool 3 and the scraping knife guides 12, 13 of the upper tool 2, the movement of the scraping knife guides 12, 13 and therefore the scraping knives 8, 9 is identical. These scraping knives are also forcibly displaced outwards resulting in a decoating of the blank by a movement of a scraping knife 8, 9 substantially perpendicular to the main extension direction of the region to be decoated.
(25) In FIG. 7, the decoating process is already complete as the sleeves are fully inserted into a recess of the scraping knife guides 11, 12 and the thrust chamfers 15 are completely worn down by the scraping knife guides 11, 14.
(26) FIG. 8 is a detailed view of the position of the scraping knives 9, 10 after completion of the decoating process according to FIG. 7. It should be noted that the scraping knives 9, 10 have already released the blank. FIG. 9 is a detailed view of the decoated region of the blank 5. The blank 5 is decoated on both sides in this region.
(27) However, it is also conceivable for the scraping knives to be used on just one side of the blank. However, the blanks are generally welded on their edges, so decoating of the edges on both sides is often necessary.
(28) FIG. 10 is a top view of a blank 22. The blank has a circumferential region 22a to be decoated which has been decoated using a device according to the invention. The directions of the arrows show the direction of movement of the scraping knives which have been used to decoat the blank 22. It can easily be conceived that with a movement which is so short (a few millimetres) the scraping process or the decoating process occurs correspondingly rapidly and therefore can lead to very low cycle times.
(29) FIG. 11 now shows a second exemplary embodiment of a device for decoating a blank comprising a press 1 which has a press stamp 6a and a pressing table 6b. The scraping knife guides 11, 12, 13 14 of the exemplary embodiment represented in FIG. 11 now simultaneously form the blank support and are each held in pairs at the decoating position or initial position by means of tension springs. Furthermore, the exemplary embodiment represented in FIG. 11 also has an end stop position block 24 and a scrap chute 25. The scrap chute 25 serves to guide away the cutting remnants which occur during cutting of the blank 5 in a controlled manner. The end position block 24 delimits the path of the press stamp 6a.
(30) In the lower tool 3 of the second embodiment, sleeves 16 are further provided which have thrust chamfers or thrust wedges 15 which are used to forcibly actuate the scraping knife guides 11, 14. In contrast to the exemplary embodiment represented in FIG. 1, the second exemplary embodiment of the device according to the invention also has thrust chamfers or thrust wedges 15 in the upper tool 2. A compression stamp 18 is further provided, which has direct contact with the blank by means of extensions 19 leading through the scraping knife guides 12, 13 which are not shown in FIG. 11. Identical to these extensions 19 in the upper tool 2, extensions 19 are also provided in the lower tool 3 which transfer the pressure of the compression stamp 18 exerted by the upper tool 2 on the blank to the lower tool 3. The extensions 19 of the lower tool 3 are also not shown in FIG. 11.
(31) FIG. 12 shows the second exemplary embodiment at the point at which the upper and lower tools 2, 3 are closed and the scraping knives 7, 8, 9, 10 engage with the blank 5. In this position, the tension springs 23 hold the scraping knife guides 11, 12, 13, 14 together at the initial position. The compression stamp 18 transfers a force onto the blank 5 by means of the extensions 19, which force is passed on to the extensions 19 of the lower tool 3.
(32) This means that the full load of the scraping knives 11, 12, 13, 14 does not lie on the blank 5 and can easily be moved laterally. The thrust chamfers 15 can clearly be seen in FIG. 12, which thrust chamfers are arranged in both the lower tool and the upper tool. At this point, the cutting stamp 17 is still in the initial position and is not engaged with the blank 5.
(33) FIG. 13 is a detailed view of the scraping knife guides 11, 12 including their scraping knives 7, 8. When the upper and lower tools 2, 3 are closed, the scraping knives 7, 8 penetrate the coating of the blank 5.
(34) If the press stamp 6a continues to move closer, the scraping knife guides 11, 12, 13, 14 are displaced outwards by means of the thrust chamfers 15 or thrust wedges 15 against the tensile force of the springs 23 and carry out the scraping process. The scrapping knives decoat the blank 5 in a region which has a main extension. The movement of the scraping knives is generally perpendicular to the main extension direction of the region of the blank 5 to be decoated.
(35) The cutting stamp 17 reaches the cutting position, FIG. 14, after the completion of the decoating. FIG. 15, which is a detailed view of a decoated region of the blank 5 from FIG. 14, clearly shows the start of the cutting process. After completion of the decoating process, the blank has decoated regions 5a. The thrust chamfers have been passed through by the scraping knife guides 11, 12, 13, 14, such that where there is further lowering of the press stamp 6a there is no further lateral movement of the scraping knife guides 11, 12, 13, 14. Only the cutting knife 17 is moved downwards, such that the scraping knife functions as a cutting edge for the cutting or punching stamp 17 at the same time.
(36) FIG. 16 shows the press moved to the end position. The cutting stamp 17 has now cut both sides of the blank 5 and the cutting remnants 26 are moved out of the work area in a controlled manner via the scrap chute 25.
(37) FIG. 17 is a detailed view of the cut region. As can be seen, the thrust chamfers 15 play no further role in the movement of the cutting stamp 17. With the device according to the invention and with the method according to the invention, a blank can easily be provided, the edges of which are decoated and cut in one work step. The above mentioned AlSi coatings are available for the coating. However, it is also conceivable for other coatings to be removed from a blank.
