| Claims 1. A method for hemming of metal sheet products, especially thick ones, by placing a metal sheet item with a circular cross-section between a stencil and a blank holder and the action over the circumferential zone of the treated item with the shaping tool during the rotation of the stencil with the blank holder characterized in that the treated item (12) is rotating with the stencil (!) and the blank holder (2) with a rotation speed lower than 10 rpm, and a tool in the shape of a roller (9) with a concave shape acts on the edge of the treated item (12), retaining the angle which leads the treated item (12) to contact the working surface of the tool (9), whereas the tool (9) acts on the edge of the item (12) with a frequency of (10 to 50) Hz and an amplitude of (2 - 6) mm, and moves towards the axis of rotation in relation to the edge, with the feed of (0.08 - 0.15) mm per rotation. 2. A method in accordance with claim 1, characterized in that after the treatment process the treated item (12) makes additionally at least one rotation with an immobilised shaping roll (9). 3. A unit for hemming of thick metal sheeting, having a stencil, mounted on a spindle placed in a head-stock placed on the body of the machine tool, and in the socket of the tailstock a rotationally mounted blank holder is mounted, between which a circle-shaped treated item made of metal sheeting is placed, characterized in that at least one tool in the zone of the edge of the treated item (12), consisting of a roller (9) with an envelope shape concave surface, placed on a support (8), connected with a controller, which makes the roller (9) move in a pulsating and reciprocating manner. 4. A unit in accordance with claim 3, characterized in that the treated item (12) is a product after shape treatment. 5. A unit in accordance with claim 3, characterized in that the treated item (12) is a pipe section. 6. A unit in accordance with claim 3, characterized in that the treated item (12) is a die stamping. 7. A unit in accordance with claim 3, characterized in that the treated item (12) is a cylindrical vessel. 8. A unit in accordance with claim 3, characterized in that the treated item (12) is a circle of metal sheet |
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Method for hemming of metal sheet products, especially thick ones, and unit for hemming of metal sheet products, especially thick ones
The subject of the invention is a method for hemming of metal sheet products, especially thick ones, and a unit for hemming of metal sheet products, especially thick ones, which is used especially for manufacturing from thick sheeting, with a thickness of over 5 mm, of spatial products with a circular outline with an envelope collar, which form bottoms, covering elements and others.
For hemming of the edges, it is necessary to act on the metal sheet envelope zone with a shaping tool
A unit for hemming of the body of a tin using at least one hemming tool is known, presented in a PL 183384 patent description, where the internal part is placed on a shaft rotating around its axis and a cooperating tool placed coaxially to the axis.
A unit and a method for shaping of spherical bowls are known, presented in a PL 384299 patent claim. A disc of a metal sheet placed on a rotating shield is passed between two forming tools which shape its surface.
A method and device for hemming of metal cylindrical surfaces, especially rings for boxes is known from a patent description PL 173806, where on the shaped surface a shaping head is placed, where the head and the treated surface rotate in relation to each other. In another solution, presented in the patent claim P 321850 on the tin body a force is exerted in the radial direction to the direction of required shaping of axial force.
A method and a device for the construction of food preparation vessels are presented in the PCT/FI96/00213 documentation. This vessel is constructed using a roller profiling method, using a bottom tool, which rotates around its axis, whereas the shaping surface of the bottom tool is constructed in such a manner, as to be compatible with the external surface of the vessel thus created, and using an upper tool, which rotates around its axis, whereas the surface of the upper tool has a shape which corresponds to the shape of the internal surface of the vessel.
A unit is known from the description US 5121621, which has a holder with multiple rollers installed on a rotating shaft, said rollers profiled to hem the edges, towards which the tin is pushed with its edge. In order to limit the hemmed edge of the tin body a cylindrical surface of an inner stationary casing is provided.
The presented solutions apply to shaping of products from thin sheeting, especially of tins. These methods of manufacturing and these devices do not solve the problem of shaping products from thick metal sheeting by hemming of sheet circle edges.
The solution described below fills a gap in the requirements for the shaping of thick sheeting.
The essence of the invention, which is a method for hemming of metal sheet products, especially thick ones, by placing a metal sheet item with a circular cross-section between a stencil and a blank holder and the action over the circumferential zone of the treated item with the shaping tool during the rotation of the stencil with the blank holder consists of the treated item rotating with the stencil and the blank holder with a rotation speed lower than 10 rpm, and a tool in the shape of a roller with a concave shape acts on the edge of the treated item, whereas the tool acts on the edge of the item with a frequency of (10 to 50) Hz and an amplitude of (2 - 6) mm, and moves towards the axis of rotation in relation to the edge, with the feed of (0.08 - 0.15) mm per rotation. It was advantageous, when after the treatment process the treated item makes additionally at least one rotation with an immobilised shaping roll.
This method is implemented in a unit in accordance with the invention for hemming of thick metal sheeting, having a stencil, mounted on a spindle placed in a head-stock placed on the body of the machine tool, and in the socket of the tailstock a rotationally mounted blank holder is mounted, between which a circle-shaped treated item made of metal sheeting is placed, which consists of having at least one tool in the zone of the edge of the treated item, consisting of a roller with an envelope shape concave surface, placed on a support, connected with a controller, which makes the roller move in a pulsating and reciprocating manner.
It is advantageous, when the treated item is a product after shape treatment.
It is also advantageous, when the treated item is a pipe section.
It is also advantageous, when the treated item is a die stamping.
It is also advantageous, when the treated item is a cylindrical vessel It is especially advantageous, when the treated item is a circle of metal sheet
The use of the solution presented in the invention enables the following technical and utility effects:
- ability to construct collar products in one shaping operation on one machine,
- ability to hem the edges of products made of stamped sheeting, especially with a thickness above 5 mm,
- ability to use for the implementation of the solution of existing machine tool units,
- ability to program the range of the movement of the shaping roller, depending on the parameters of the treated material,
- ability to repeat the hemming process multiple times through multiple passes of the shaping roller,
- ability to perform the hemming process using two rollers, placed on the opposite supports,
- significant lowering of the labour demand required to manufacture products,
- lowering the manufacturing costs for products of this type. The subject of the invention, presented in the below example of implementation, where in order to better illustrate the method of hemming the sheets on a schematic diagram an example unit for hemming of the sheets was presented, where on fig. 1 the unit was presented in a side view, on fig. 2 in a top view and on fig. 3 a diagram of a cooperating tool with the metal sheet circle was presented.
Device for hemming of flanges for thick metal sheet products, has a stencil 1 and blank holder 2. Stencil 1 is placed on a rotating spindle 3, placed in a head-stock 4 placed on the body 5, on the cradles 6 of which on the opposite side of the spindle a sliding tailstock 7 is placed. In the socket of the tailstock the blank holder 2 is placed. On both sides of the body 5 supports 8 are located, on which rollers 9 are located, which perform reciprocating and pulsating movements, controlled by a CNC controller, which is not shown in the figure, and connected with the pressure and control mechanism 10.
The stencil 1 on the frontal surface may have an opening, in which a centring peg 1J_ is placed, which after the fixing of the treated item 12, on the other side will be pressed by the blank holder 2.
The treated item 12 is an item after shape treatment, and especially, depending on the requirements, the treated item 12 is a pipe section, die stamping, sheet circle or a cylindrical vessel.
A method for hemming of metal sheet products, especially thick ones, consists of the treated item 12 being placed between the stencil 1 and the blank holder 2. The treated item 12 rotates with the stencil 1 and blank holder 2 with a rotational speed of less than 10 rpm, and the edge of the treated item 12 is acted upon by a tool in the form of previously shaped roller 9 with a concave shape. The tool controlled by a CNC controller acts upon the edge of the circle 9 with a frequency of (10 to 50) Hz and amplitude of (2 - 6) mm, and moves towards the rotation axis in relation to the edge wit a feed of (0.08 - 0.15) mm per rotation.
After the treatment process the treated item (12) makes additionally at least one rotation with an immobilised shaping roll (9).