POSITIONING DEVICE AND POSITIONING ASSEMBLY FOR HOLDING A FLAT FLEXIBLE PART, AND SHEET MATERIAL PROCESSING MACHINE

Abstract

A positioning device (38) for holding a flat flexible part, especially a sheet, on a positioning surface is described. It comprises a body (44) with a fluid inlet port (52) for supplying a driver fluid to the body (44), a fluid outlet port (58) for draining the driver fluid from the body (44), and a suction opening for aspiring the flat flexible part. A circulation channel (60) connects the fluid inlet port (52) and the fluid outlet port (58) and a suction channel (70) connects the suction opening to the circulation channel (60). The suction channel (70) is connected to the circulation channel (60) adjacent to a section (64) of reduced cross section area such that a jet pump (71) is formed. Every cross section (S.sub.c) of the circulation channel (60) and/or every cross section (S.sub.s) of the suction channel (70) along its entire respective length have/has a smooth rim. Additionally, a positioning assembly comprising at least one such positioning device (38) is presented. Moreover, a sheet material processing machine is introduced which comprises at least one positioning assembly.

Claims

1. A positioning device for holding a flat flexible part, especially a sheet, on a positioning surface, the positioning device comprising: a body with a fluid inlet port for supplying a driver fluid to the body, a fluid outlet port for draining the driver fluid from the body, and a suction opening for aspiring the flat flexible part, wherein the suction opening is arranged within the positioning surface being an outer surface of the body, a circulation channel connecting the fluid inlet port and the fluid outlet port, wherein the circulation channel comprises a section of reduced cross section area, and a suction channel connecting the suction opening to the circulation channel, wherein the suction channel is connected to the circulation channel adjacent to the section of reduced cross section area such that a jet pump is formed, wherein every cross section of the circulation channel and/or every cross section of the suction channel along its entire respective length has a smooth rim, so that a contour delimiting every cross section of the circulation channel and/or every cross section of the suction channel along its entire respective length does not have corners or kinks.

2. The positioning device according to claim 1, wherein a course of the cross section of the circulation channel along the length of the circulation channel comprises one single discontinuity.

3. The positioning device according to claim 1, wherein a cross section of the suction channel evolves continuously along the entire length of the suction channel.

4. The positioning device according to claim 1, wherein a direction of extension of the circulation channel evolves continuously along the entire length of the circulation channel and/or in that a direction of extension of the suction channel evolves continuously along the entire length of the suction channel.

5. The positioning device according to claim 1, wherein the circulation channel comprises a bend, especially a bend of approximately 180.

6. The positioning device according to claim 1, wherein the fluid inlet port and the fluid outlet port are arranged on a same end of the body.

7. The positioning device according to claim 1, wherein a curvature radius of a wall laterally delimiting the circulation channel lies within a range of 0.2 mm to 30 mm, in particular of 0.5 mm to 20 mm.

8. The positioning device according to claim 1, wherein at least 60%, preferably at least 75%, more preferably at least 90%, of the length of the circulation channel have a cross section area being at least twice as big as the cross section areas of the remaining portions of the length of the circulation channel.

9. The positioning device according to claim 1, wherein a cleaning fluid inlet port is arranged on the body.

10. The positioning device according to claim 9, wherein a cleaning fluid channel fluidically connects the cleaning fluid inlet port to the circulation channel or to the suction channel, wherein a cross section of the cleaning fluid channel has a smooth rim along its entire length.

11. The positioning device according to claim 1, wherein the body is an additively manufactured part.

12. The positioning device according to claim 1, wherein the section of reduced cross section area of the circulation channel comprises a nozzle having a substantially circular cross section.

13. A positioning assembly for holding a flat flexible part, especially a sheet, on a holding surface, comprising a base with a central air supply duct and at least one positioning device according to claim 1, wherein the positioning device is mounted on the base part such that the fluid inlet port of the positioning device is fluidically connected to the central air supply duct and that the positioning surface forms the holding surface.

14. A sheet material processing machine comprising the positioning assembly of claim 13.

Description

[0050] FIG. 1 shows a sheet material processing machine 10 (in the following: machine 10).

[0051] In the example shown, the machine 10 is configured for cutting a sheet material and is composed of five units each performing a certain treatment on the sheet material.

[0052] A first unit is a feeder unit 10a for providing or feeding sheets 12 to be processed. For illustrative purposes, only one sheet 12 is represented in the feeder unit 10a.

[0053] The second unit comprises a platen press 14 which is configured for cutting the sheet 12. Consequently, the second unit is a platen press unit 10b.

[0054] The third unit is a stripping unit 10c which is configured for eliminating certain waste elements from the cut sheet 12.

[0055] The fourth unit is a blanking unit 10d. In this unit the actually desired portion of the cut sheet 12 is withdrawn therefrom and put on a pile 16.

[0056] The fifth unit is a waste evacuation unit 10e and serves for the elimination of further waste elements of the cut sheet 12.

[0057] The sheet 12 is transported through the machine 10 by a conveyor system 18 essentially comprising a conveyor belt 20 to which a plurality of gripper units 22 are attached, which are configured for selectively gripping the sheet 12.

[0058] The platen press unit 10b, the stripping unit 10c and the blanking unit 10d additionally comprise a positioning assembly 24 for holding the sheet 12, on a holding surface 26.

[0059] In the example shown in FIG. 1, the holding surface 26 is a top surface of the positioning assembly 24.

[0060] During the processing of the sheet 12 in any one of the platen press unit 10b, the stripping unit 10c and the blanking unit 10d, a leading edge of the sheet 12 will be gripped by a corresponding gripping unit 22 and a trailing edge of the sheet 12 will be held by the corresponding positioning assembly 24 (cf. travelling direction T).

[0061] FIG. 2 shows the positioning assembly 24 in more detail.

[0062] It comprises a base part 28 with a central air supply duct 30.

[0063] Thus, pressurized air can be supplied to the base part 28 via the central air supply duct 30.

[0064] The base part 28 also comprises a plurality of fluid outlet ports 32 which are in fluid communication with the central air supply duct 30.

[0065] Moreover, the base part 28 comprises a cleaning fluid inlet port 34. Thus, a cleaning fluid may be supplied to the positioning assembly 24 via the cleaning fluid inlet port 34.

[0066] The base part 28 additionally comprises cleaning fluid outlet ports 36 being in fluid communication with cleaning fluid inlet port 34.

[0067] In the example shown in FIG. 2, two positioning devices 38 are mounted on the base part 28 via fastening means 40, e.g. bolts or rivets.

[0068] A gasket 42 is interposed between the base part 28 and each of the positioning devices 38.

[0069] One of the positioning devices 38 will be explained in more detail with reference to FIGS. 3 to 9. Since the two positioning devices 38 shown in FIG. 2 are substantially identical, the following explanations apply to both of them.

[0070] The positioning device 38 comprises a body 44 being an additively manufactured part.

[0071] One outer surface of the body 44 is a positioning surface 46.

[0072] The positioning surface 46 forms a portion of the holding surface 26.

[0073] In the representation of FIG. 2 the positioning surface 46 is the top surface of the body 44.

[0074] The body 44 also comprises a connection surface 48 also being an outer surface thereof.

[0075] The connection surface 48 is arranged opposite the positioning surface 46 and thus is a lower surface of the body 44 in the representation of FIG. 2.

[0076] On the positioning surface 46 suction openings 50 are provided. These suction openings 50 are configured for aspiring the sheet 12 such that it is held on the positioning surface 46.

[0077] On the connection surface 48 fluid inlet ports 52 are provided for supplying a driver fluid to the body 44 (cf. FIGS. 3 and 4).

[0078] Additionally, cleaning fluid inlet ports 54 are arranged on the connection surface 48 (cf. FIG. 4).

[0079] The body 44 also has a lateral surface 56 which connects the positioning surface 46 and the connection surface 48.

[0080] On the lateral surface 56 fluid outlet ports 58 are provided for draining the driver fluid from the body 44 (cf. FIGS. 4 and 5).

[0081] The fluid inlet ports 52 and the fluid outlet port 58 are arranged on the same end of the body 44. In the representation of FIG. 4 they are provided on an upper end thereof.

[0082] Each of the fluid inlet ports 52 is connected to a corresponding fluid outlet port 58 by a circulation channel 60. In other words, the circulation channel 60 extends from the respective fluid inlet port 52 to the respective fluid outlet port 58 (cf. FIG. 8).

[0083] The circulation channel 60 is generally shaped like a hairpin, i.e. it comprises a bend 62 of approximately 180.

[0084] Downstream the bend 62, the circulation channel comprises a section 64 of reduced cross section area.

[0085] The section 64 comprises a nozzle 66 for accelerating a flow of driver fluid flowing through the circulation channel 60.

[0086] The nozzle 66 has a substantially circular cross section (cf. FIG. 9).

[0087] When considering a cross section S, of the circulation channel 60 along its length, this cross section has a single discontinuity 68 at the downstream end of the nozzle 66.

[0088] In the remaining sections of the circulation channel 60 the cross section S, evolves continuously.

[0089] For the ease of representation only some of the cross sections S, of the circulation channel 60 are designated with a reference sign in FIG. 8.

[0090] In this context, approximately 87% of the length of the circulation channel 60 have a cross section area being at least twice as big as the cross section areas of the remaining portions of the length of the circulation channel 60.

[0091] This means that the circulation channel 60 has a relatively big and relatively uniform cross section area in all sections outside the section 64 of reduced cross section area.

[0092] Also a direction of extension E.sub.c of the circulation channel 60 evolves continuously along the entire length of the circulation channel 60, i.e. the circulation channel 60 has no corners or kinks.

[0093] Furthermore, every cross section S.sub.c of the circulation channel 60 along its entire length has a smooth rim, i.e. the contour delimiting the cross section S.sub.c also does not have corners or kinks.

[0094] In particular, a curvature radius r of a wall laterally delimiting the circulation channel 60 lies within the range of 0.5 mm to 20 mm.

[0095] For the ease of representation only some of the curvature radius r of the circulation channel 60 are designated with a reference sign in FIG. 8.

[0096] Within the body 44 also a suction channel 70 is provided which connects the suction opening 50 to the circulation channel 60.

[0097] The suction channel 70 surrounds the circulation channel 60 in the section 64 of reduced cross section area and is connected to the circulation channel 60 in the adjacent to the section 64 of reduced cross section area such that a jet pump 71 is formed.

[0098] More precisely, the suction channel 70 merges into the circulation channel 60 right at the position of the discontinuity 68.

[0099] Thus, a flow of driver fluid flowing through the circulation channel 60 is accelerated by the nozzle 66 and accelerates fluid being present in the suction channel 70 such that the sheet 12 is aspired via the suction opening 50.

[0100] A cross section S.sub.s of the suction channel 70 evolves continuously along the entire length of the suction channel 70. The course of the cross section S.sub.s of the suction channel 70 does not have discontinuities.

[0101] Again, only two representative cross sections S.sub.s are designated with a reference sign in FIGS. 5 and 9.

[0102] Also a direction of extension E.sub.s of the suction channel 70 evolves continuously along the entire length of the suction channel 70.

[0103] Moreover, like the circulation channel 60, also every cross section S.sub.s of the suction channel 70 along its entire respective length has a smooth rim.

[0104] It is noted that even though the suction openings 50 are generally D-shaped, a rim of a cross section the suction openings 50 and thus a rim of the cross section of the suction channel 70 does not comprise kinks or corners. This means that all corners of the D-shape are rounded.

[0105] Furthermore, a cleaning fluid channel 72 is provided which fluidically connects the cleaning fluid inlet port 54 to the suction channel 70 (cf. FIGS. 7 and 9).

[0106] In the example shown in the Figures, the cleaning fluid channel 72 is bifurcated at its downstream end such that a first cleaning fluid channel part 72a and a second cleaning fluid channel part 72b merge into the suction channel 70.

[0107] The cleaning fluid channel 72 has a cross section which has a smooth rim along its entire length.

[0108] It is understood that in the embodiments described in connection with the Figures, the sheet 12 is used as a representative example of a flat flexible part. This means that the machine 10, the positioning assembly 24 and the positioning device 38 can also be used in connection with any other flat flexible part.