Conveying screw for a cutting and separating device

Abstract

A conveying screw for a cutting and separating device, including a screw shaft having at least one helical screw flight integrally moulded thereon, which, in an installed position, has a front flank for transporting a foodstuff by pushing, a rear flank arranged on the opposite side, and, at its distal end between the front flank and the rear flank, a cylindrical portion, which is formed in the transition region to the front flank of the screw flight with a sharpened cutting edge, the sharpened cutting edge having a positive rake angle (γ) arranged between the front flank and a processing plane oriented at right angles to the screw shaft. The cutting performance of the cutting and separating device are significantly improved as the sharpened cutting edge is formed from a groove made on a distal end of the front flank, the outer contour of which groove cuts into the cylindrical portion.

Claims

1. A conveying screw for a cutting and separating device, comprising: a screw shaft having at least one helical screw flight integrally moulded thereon, which, in an installed position, has a front flank for transporting a foodstuff by pushing, a rear flank arranged on the opposite side, and, at its distal end between the front flank and the rear flank, a cylindrical portion, which is formed in the transition region to the front flank of the screw flight with a sharpened cutting edge, the sharpened cutting edge having a positive rake angle (γ) arranged between the front flank and a processing plane oriented at right angles to the screw shaft, wherein the sharpened cutting edge is formed from a groove made on a distal end of the front flank, the outer contour of which groove cuts into the cylindrical portion.

2. The conveying screw according to claim 1, wherein the rake angle (γ) is between 10° and 50.

3. The conveying screw according to claim 1, wherein between the front flank and the cylindrical portion there is a wedge angle (δ) of 40° to 80.

4. The conveying screw according to claim 1, wherein a radius or a bevel is arranged between the cylindrical portion and the rear flank.

5. A cutting and separating device with the conveying screw according to claim 1, wherein the conveying screw is rotatably mounted in a pressure housing of a shredding drum, which is formed with an inlet opening at a first end portion and with an outlet opening at a second end portion, wherein that a plurality of cutting openings are arranged in a pressure housing portion of the pressure housing and pass right through the pressure housing portion from an inner wall to an outer wall.

6. The cutting and separating device according to claim 5, wherein the sharpened cutting edge is formed on a sweeping section of the conveying screw which sweeps over the cutting openings.

7. The cutting and separating device according to claim 5, wherein the cylindrical portion of the screw flight has a width (bs) which is at least the diameter (Ø.sub.O) of the cutting openings on the inner wall.

8. The cutting and separating device according to claim 5, wherein the cutting openings are oriented with hole axes inclined at an angle (α.sub.O1, α.sub.O2) in relation to the inner wall.

9. The cutting and separating device according to claim 8, wherein the angle (α.sub.O1, α.sub.O2) comprises a first angle (α.sub.O1) which is arranged on the side of the cutting opening facing away from the inlet opening of the pressure housing between its hole axis and the inner wall.

10. The cutting and separating device according to claim 9, wherein the first angle (α.sub.O1) is between 60° and 88°.

11. The cutting and separating device according to claim 5, wherein each cutting opening on the inner wall has a cutting opening edge facing the outlet opening and a drawing-in edge facing the inlet opening.

12. The cutting and separating device according to claim 8, wherein the angle (α.sub.O1, α.sub.O2) comprises a second angle (α.sub.O2) which is located in the circumferential direction of the pressure housing portion between the hole axis and the radius (R) of the pressure housing portion.

13. The cutting and separating device according to claim 12, wherein the second angle (α.sub.O2) is between 2° and 30°.

14. The cutting and separating device according to claim 12, wherein the second angle (α.sub.O2) is aligned counter to a direction of rotation (M) of the conveying screw.

15. The conveying screw according to claim 2, wherein between the front flank and the cylindrical portion there is a wedge angle (δ) of 40° to 80°, and wherein a radius or a bevel is arranged between the cylindrical portion and the rear flank.

16. A cutting and separating device with the conveying screw according to claim 15, wherein the conveying screw is rotatably mounted in a pressure housing of a shredding drum, which is formed with an inlet opening at a first end portion and with an outlet opening at a second end portion, wherein that a plurality of cutting openings are arranged in a pressure housing portion of the pressure housing and pass right through the pressure housing portion from an inner wall to an outer wall.

17. The cutting and separating device according to claim 16, wherein the sharpened cutting edge is formed on a sweeping section of the conveying screw which sweeps over the cutting openings, and wherein the cylindrical portion of the screw flight has a width (bs) which is at least the diameter (Ø.sub.O) of the cutting openings on the inner wall.

18. The cutting and separating device according to claim 17, wherein the cutting openings are oriented with hole axes inclined at an angle (α.sub.O1, α.sub.O2) in relation to the inner wall, and wherein the angle (α.sub.O1, α.sub.O2) comprises a first angle (α.sub.O1) which is arranged on the side of the cutting opening facing away from the inlet opening of the pressure housing between its hole axis and the inner wall.

19. The cutting and separating device according to claim 9, wherein the first angle (α.sub.O1) is between 60° and 88°, and wherein each cutting opening on the inner wall has a cutting opening edge facing the outlet opening and a drawing-in edge facing the inlet opening.

20. The cutting and separating device according to claim 19, wherein the angle (α.sub.O1, α.sub.O2) comprises a second angle (α.sub.O2) which is located in the circumferential direction of the pressure housing portion between the hole axis and the radius (R) of the pressure housing portion, wherein the second angle (α.sub.O2) is between 2° and 30°, and wherein the second angle (α.sub.O2) is aligned counter to a direction of rotation (M) of the conveying screw.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For better understanding, the invention is explained in more detail below with reference to six figures showing in:

(2) FIG. 1 a longitudinal section through a cutting and separating device with a shredding drum according to a first embodiment and a conveying screw arranged therein;

(3) FIG. 2: a longitudinal section through the shredding drum according to FIG. 1;

(4) FIG. 3: an enlarged longitudinal section through the detail of FIG. 2;

(5) FIG. 4: a cross section through the cutting and separating device according to FIG. 1 in the area of the pressure housing portion;

(6) FIG. 5: a longitudinal section through the conveying screw according to FIG. 1 and

(7) FIG. 6: a cross section through the cutting and separating device with a shredding drum according to a second embodiment in the area of the pressure housing portion.

DETAILED DESCRIPTION OF THE INVENTION

(8) FIG. 1 shows a longitudinal section through a cutting and separating device 100 with a shredding drum 110 and a conveying screw 130 arranged coaxially therein. The shredding drum 110 comprises a pressure housing 111, on the first end portion 112 of which an inlet opening 113 is formed, through which the foodstuff to be comminuted is fed to the shredding drum 110. At the opposite end of the pressure housing 111 there is a second end portion 114 on which an outlet opening 115 is formed, through which sinewy material and unusable solids are conveyed out of the pressure housing 111. The inlet opening 113 and the outlet opening 115 each form opposite, axial openings of the pressure housing 111.

(9) An upstream connection means 119a is attached to the first end portion 112 of the pressure housing 111 on the shredding drum 110, via which a detachable connection to a feed channel or a feed hopper (not shown here) can be established. The shredding drum 110 also has, on the second end portion 114 of the pressure housing 111, a downstream connection means 119b, to which, for example, a throttle valve (also not shown) for controlling the food pressure within the pressure housing 111 can be attached.

(10) The pressure housing 111 of the shredding drum 110 has a pressure housing portion 116 with a multiplicity of cutting openings 120 which run continuously from an inner wall 117 of the pressure housing portion 116 to an outer wall 118. The food component desired for further processing escapes through the cutting openings 120.

(11) The conveying screw 130 includes a rotatably driven screw shaft 131 whose axis of rotation is aligned with a housing longitudinal axis X of the pressure housing 111. At least one screw flight 132 is formed on the screw shaft 131 and surrounds the screw shaft 131 in a spiral shape in the axial direction. When the screw shaft 131 rotates, due to its pitch, the food in the pressure housing 111 is pushed forward from the inlet opening 113 in the direction of the outlet opening 115. During this process, a pressure builds up inside the food to be processed, which pushes the food to be processed into the cutting openings 120 so that a food stud is formed within the cutting opening 120. Due to the continuous feed movement of the food to be processed applied by the conveying screw 130, the food stud tears off the food remaining in the pressure housing portion 116 and penetrates the pressure housing 111 through the cutting opening 120 to the outside.

(12) However, only in the area of the pressure housing portion 116, i.e. in a sweeping section 134 of the conveying screw 130 sweeping over the cutting openings 120, at its outer end, the screw flight 132 has a sharpened cutting edge 133, the shape and function of which will be explained below in connection with FIG. 4 to FIG. 6.

(13) As can be seen particularly well in FIG. 2, the cutting openings 120 do not run through the pressure housing portion 116 in the radial direction, but are inclined with their hole axis 121. The inclination of the hole axis 121 is selected in such a way that it faces the inlet opening 113 on the inner wall 117.

(14) An enlargement of the detail relating to the cutting openings 120, among other things, is shown in FIG. 3. The cutting openings 120 are designed as stepped bores with an outer, larger-diameter cross-section and an inner, smaller-diameter cross-section, whereby the food component required for further processing is heated relatively little and the gem load is reduced, since the food stud already severed in the cutting openings 120 can expand into the larger diameter cross-section.

(15) However, only the diameter Ø.sub.O of the cutting openings 120 arranged in the area of the inner wall 117 is involved in the comminution work of the food to be processed. The hole axis 121 is inclined at a first angle α.sub.O1. The angle α.sub.O1 is located on the side of the outlet opening 115 between the hole axis 121 and the inner wall 117 or the longitudinal axis X of the pressure housing 111.

(16) Each cutting opening 120 has a circumferential opening edge 122 in the transition area to the inner wall 117 of the pressure housing portion 116, of which a part facing the outlet opening 115 serves as a cutting opening edge 122a and a part facing the inlet opening 113 as a drawing-in opening edge 122b for the food to be chopped. The inclination of the hole axis 121 at the first angle α.sub.O1 results in a particularly sharp cutting opening edge 122a at the same acute angle α.sub.O1. The drawing-in opening edge 122b, on the other hand, has an obtuse angle greater than 90° and thereby promotes the entry of the food to be chopped into the respective cutting opening 120.

(17) The size of the obtuse angle of the drawing-in opening edge 122b is 180° minus the first angle α.sub.O1.

(18) FIG. 4 shows a cross section through the cutting and separating device 100 with a shredding drum 110 according to a first embodiment, in which the cutting openings 120 run radially towards the longitudinal axis X of the housing in the cross-sectional plane. Cutting openings 120 arranged axially offset in the image plane are arranged in relation to the cutting openings 120 in front of them in the image plane in such a way that their hole axes 121 are aligned offset by an angle β.sub.O in the circumferential direction with respect to one another.

(19) The conveying screw 130 rotates in the direction of rotation M, clockwise in the image plane of FIG. 4. The screw flight 132 has a front flank 140, which is arranged at the front in the direction of rotation M, and a rear flank 141, which is arranged at the rear in the direction of rotation M. A cylindrical portion 143 can be seen between the front flank 140 and the rear flank 141 at each distal end 142 of the screw flight 132, which is shaped complementary to the inner wall 117 of the pressure housing portion 116.

(20) The sharpened cutting edge 133 comprises a groove 145 placed in the front flank 140, wherein the outer contour 146 (FIG. 5) of which adjoins the cylindrical portion 143 and merges into it. The groove 145 is formed equidistant to the cylindrical portion 143 over the axial course of the conveying screw 130 and extends over the entire section 134 sweeping over the cutting openings 120. The groove 145 is always formed in the radial direction only over a part of the front flank 140 of the screw flight 132.

(21) In the direction of the screw shaft 131, an inner contour 148 of the groove 145 borders on the front flank 140 of the screw flight 132, wherein the front flank 140 extends up to the screw shaft 131. The groove 145 has a width R.sub.N in the radial direction which is less than preferably 30%, particularly preferably 25%, of a load-bearing radius R.sub.S of the screw flight 132.

(22) With the help of the sharpened cutting edge 133, in particular, adhesions of the food to be processed on the inner wall 117 of the pressure housing portion 116 can be peeled off, so that they do not permanently lie over the cutting openings 120 and thereby prevent the food to be processed from entering the cutting openings 120. Such adhesions usually consist of collagenous material, which has up to twenty times the strength of lean meat and hardly penetrates into the cutting openings 120 due to its high strength. Buildup peeled off by the sharpened cutting edge 133 is transported in the direction of the outlet opening 115 and removed there from the shredding drum 110.

(23) In a longitudinal section through the conveying screw 130, FIG. 5 shows that the sharpened cutting edge 133 is formed from the outer contour 146 of the groove 145 and the cylindrical portion 143. The sharpened cutting edge 133 has a rake angle γ that is spanned between a processing plane 144 that is perpendicular to the axial extension of the conveying screw 130 and the outer contour 146 of the groove 145. A wedge angle δ is arranged between the outer contour 146 of the groove 145 and the cylindrical portion 143 of the screw flight 132. Since the clearance angle is always 0° due to the cylindrical portion 143 of the screw flight 132, the sum of the rake angle γ and the wedge angle δ is always 90°.

(24) The sharpened cutting edge 133 is only present in the sweeping section 134 traversing the cutting openings 120. In a feeding section 135 of the conveying screw 130, which protrudes beyond the pressure housing 111 of the shredding drum 110 between the pressure housing portion 116 with the cutting openings 120 and the inlet opening 113, the conveying screw 130 only has a conventional screw flight 132, which has a cutting edge being designed for example with a rake angle γ of 90°. Since there are no cutting openings 120 in the pressure housing 111 in this area, they are not clogged by adhesions of the food to be processed and consequently do not have to be removed from the sharpened cutting edge 133 of the conveying screw 130.

(25) For a high cutting performance of the cutting and separating device 100, the screw flight 132 in the area of the section 134 sweeping over the cutting openings 120 has a width b.sub.S that corresponds at least to the diameter Ø.sub.O of the cutting openings 120 on the inner wall 117 of the pressure housing portion 116. The width b.sub.S forms the perpendicularly distance between the front flank 140 and the rear flank 141 of the screw flight 132.

(26) A bevel 147 is formed in the transition area between the cylindrical portion 143 of the screw flight 132 and the associated rear flank 141, which also contributes to reducing the heating of the food to be processed. Instead of a bevel 147, a radius or another geometric shape can also be provided in the transition area between the cylindrical portion 143 and the rear flank 141; it is always essential that there is a reduction in the material of the screw flight 132 in this area. The bevel 147 runs in accordance with the groove 145 exclusively in the sweeping section 134 of the conveying screw 130 that sweeps over the cutting openings 120.

(27) FIG. 6 shows a cross section through the cutting and separating device 100 with a shredding drum 110 according to a second embodiment in the area of the pressure housing portion 116. The cutting openings 120 introduced therein have hole axes 121 which, in addition to the first angle α.sub.O1, are also inclined with a second angle α.sub.O2.

(28) The angle α.sub.O2 is applied laterally to the radius R of the pressure housing portion 116 and is thus spanned in the circumferential direction of the pressure housing portion 116. The hole axis 121, which is additionally inclined at the second angle α.sub.O2 according to the second embodiment, runs in the direction of the inner wall 117 counter to the direction of rotation M of the conveying screw 130, so that the cutting openings 120 have a cutting opening edge 122a on their side facing away from the front flank 140 of the screw flight 132. The inclination of the hole axis 121 at the second angle α.sub.O2 results in an equally sharp cutting opening edge 122a between the inner wall 117 of the pressure housing portion 116 and the cutting opening 120 at the same acute angle α.sub.O2.

LIST OF REFERENCE NUMBERS

(29) 100 cutting and separating device 110 shredding drum 111 pressure housing 112 first end portion pressure housing 113 inlet opening 114 second end portion pressure housing 115 outlet opening 116 pressure housing portion 117 inner wall pressure housing portion 118 outer wall pressure housing portion 119a upstream connection means 119b downstream connection means 120 cutting openings 121 axis cutting openings 122 opening edge 122a cutting edge 122b drawing-in edge 130 conveying screw 131 screw shaft 132 screw flight 133 sharpened cutting edge 134 cutting openings sweeping section 135 feeding section 140 front flank 141 rear flank 142 distal end 143 cylindrical portion 144 processing plane 145 groove 146 outer contour groove 147 bevel 148 inner contour groove b.sub.S width of screw flight M direction of rotation conveying screw R.sub.N width groove R.sub.S radius screw flight R radius pressure housing portion X housing longitudinal axis α.sub.O1 first angle axis cutting openings α.sub.O2 second angle axis cutting openings β.sub.O offset angle cutting openings Ø.sub.O diameter cutting openings γ rake angle cutting edge δ wedge angle cutting edge