CA1187399A

CA1187399A - Rotary cutter assembly

Info

Publication number: CA1187399A
Application number: CA000416831A
Authority: CA
Inventors: Manfred A.A. Lupke; Gerd P.H. Lupke
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-12-28
Filing date: 1982-12-02
Publication date: 1985-05-21
Also published as: EP0083164A1; EP0083164B1; DE3269027D1

Abstract

ABSTRACT OF THE DISCLOSURE

ROTARY CUTTER ASSEMBLY
The application discloses a method and an apparatus for perforating thermoplastic tube, especially corrugated tube.
The cutter includes spindles that carry punch-type cutters and are revolved around the tube so that the punches follow epicycloids with cusps at the surface of the tube.
the punches thus penetrate the tube without tangential movement. The spindles are equipped with ribs to engage the corrugations of the tube to advance the tube through the apparatus.

Description

'3~ , ROTARY CUTTER ASSEMBLY
The present invention relates to an apparatus for perforating a tllbe with a punch, and particularly for perforating thermoplastic tubes at spaced points. The perforated tubes may be used in underground drainage applications and they may be formed with annular or helical corrugations.
Punching apparatus of the type in question permits the production of perforations of various controlled shapes and sizes. However, the known punching apparatus, for example those disclosed in DE-A 1778094 and DE-A 1779579 cannot work at high production speeds. This contrasts with apparatus for cutting circumferential slots in the tube, as with rotary cutters. Reference may be made, for example to US-A 3824886, US-A 3957386 and US-A 4180357 for apparatus of this type. Slot cutting methods can be carried out at high speed, but cannot produce holes of~ varying shapes or small sizes. Hole size control can also be a problem when pipe dimensions are not p~rfectly uniform.
According to the present invention, there is provided, in an apparatus for perforating a tube, a punch and means for revolving the punch about the tube in an epicycloidal path such that the punch perforates the tube at cusps ~f the epicycloidal path.
The operation of this punch is completely rotary and continuous, so that it can be used at very high speeds.

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In the accompanying drawings, which i11ustrate an exemplary embodiment of the present invention.
Figure 1 is a schematic illustration showing the position of a punch on a tool holder and a portion of the 5 path of the punch with respect to a tube to be perforated, Figure 2 is a sectional side elevation, taken on line 2-2 in Figure 3 of an apparatus for perforating corrugated tubing;
Figure 3 is a section on line 3-3 in Figure 2j Figures 4 and 5, located on the same sheet on Figure 1, are of front and side views, partly in section, of a punch for use in the apparatus of Figures 1 and 2;
Figure 6, located on the same sheet as Figure 3, is a partly sectional schematic showing the punch as it per-forates the wall of a tube; and Figure 7, located on the same sheet as Figure 2,illustrates a length of corrugated tube after being per-forated.
Referring to the drawings, Figure 1 illustrates a cross section of a tube 10 with a central axis 0. The tube 10 is corrugated, having a wall thickness T in the troughs between the peaks 11. The external radius of the tube at the troughs is A.
A cutter for perforating the tube includes a tool holder in the form of a cylindrical spindle 12 with a portion 34 of radius B tangential to the tube 10 at the base of the illustrated trough. A punch 14 is mountecl on the portion 34 and projects radially a distance slightly greater than the tube wall thickness T. The spindle 12 rotates about its axis X causing the punch 14 to rotate about the axis X. The spindle is in turn caused to revolve in a circular path about the central axis 0 of the tube.
The ratio of the angular velocity of the toolholder about axis X to the angular Yelocity of axis X about axis 0 is A:B. This means that the portion 34 of the spindle 12 rolls about the tube 10 on a circle of radius A and the punch is caused to follow an epicycloidal path E having a cusp which engages the surface of the tube at point P.

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At the point P, the punch 1~ perForates the wall of the tube 10 to form an aperture without exerting a tangential force on the tube.
In the embodiment schematically illustrated in Figure l, the radii A and B are equal so that the angular velocities of the tool 14 about axis X and of axis X
about axis 0 are equal. The epicycloidal path E is a cardoid with a single cusp. In other embodiments, the radii A and B may not be equal. They are preferably in a simple whole number ratio e.g. l:2, 2:1 or 3:l. In any event, even if the radii A and B are not in a simple whole number ratio, the angular velocities are in the ratio A:B to produce the desired epicycloidal path.
_ In Figure 1, a single cutter is shown for simplicity of illustration. In the apparatus illustrated in Figures

2 and 3, three cutters are disposed symetrically about the tube. In alternative embodiments, other numbers of cutters may be employed.
Referring more specifically to Figures 2 and 3, the apparatus illustrated includes a housing 15 with end walls l6 and 17. End wall 17 has a central circular opening l9 for receiving a pipe to be perforated. The end wall l6 has a larger circular opening that is aligned with the opening 19 and has a counterbore on the outside. A ball bearing 22 is fitted into the counterbore and is retained in position by an end cover 22a. The bearing 22 carries the cylindrical sleeve of an adaptor 20. The adaptor 20 also has a circular flange fastened to the side face of a sheave 2g by cap screws 29a. The adaptor 20 and sheave 29 have a through bore 18 that is the same size as the opening l9 in end wall 17 and aligns with that opening so that a tube 10 may pass into and out of the apparatus through the openings 18 and 19.
A stationary ring gear 21 is secured to the inside face of wall 17 by bolts 21a. The gear is aligned with the opening 19 so that the tube 10 can pass through the gear. The hub of che gear 21 carries a ball bearing 23, 7~9~

which in turn supports a gear housing 25. The housing is sealed to the gear 21 by seals 25a and 25b.
The gear housing 25 carries three shafts 26a parallel to the gear 21. A pinion 26 is keyed to each of the shafts 26a and meshes with the teeth 24 of the ring gear 21. Each shaft 26a also carries a gear 26b.Three idler gears 28 carried by the housing 25 rnesh with the gears 26b.
Three drive bars 30 (one shown) extend between the gear housing 25 and the sheave 29. The bars are secured to both the housing and the sheave so that these parts rotate as a unit.
Also extending between the gear housing 25 and the sheave 29 are three spindles 33. At one end each spindle shaft ex~ends into the gear housing 25 and is keyed to a gear 27 meshing with a respective one of the idlers at 28. The other end of the spindle shaft is mounted on the sheave 29 by ball bearing 33A.

Between the gear housing 25 and sheave 29 each of the spindles 33 has an enlarged cylindrical section 34 that serves as a tool holder. This section 34 carries a helical rib 35 on its outer surface and a punch at the location indicated by the circle Y. The punch will be described in more detail in connection with Figures 4 and 5.
A drive shaft 32 extends through the housing 15, parallel to the tube 10. It is mounted in bearings 32a and 32b in the end walls 16 and 17 respectively. The shaft 32 carries sheave 40 aligned with sheave 29. Sheave 40 drives sheave 29 through a series of V belts 31.
As mentioned above, the punch is more clearly illustrated in Figures 4 and 5. As illustrated in those figures, the body 34 of the spindle 33 has a stepped bore 37a aligned with the rib 35. A cylindrical body 37 of t~e punch fits into the bore 37a and is held in place by a cap screw 38 extending into th~ bore 37a from the opposite side and threaded into a bore in the inner end of body 37. The ~73~39 punch has a cutting head 36 with V shaped cutting edge for cutting rectangular slots in the tube. The punch is shown in Figure 6 engaged with the wall of the tube I0 and piercing the tube in the desired manner. Figure 7 illustrates an helically corrugated tube I0 with slots 40 produced by the punch.
In operation of the apparatus, the drive shaft 32 is driven from an external power source of any appropriate sort. This drives the sheave 40, the belts 31 and sheave lO 29. Rotation of sheave 29 acts through drive bar 30 to rotate the gear housing 25. As the sheave 29 and gear housing 25 rotate, the spindles 33 are revolved about the tube 10 extending through the housing. The gear train consisting of stationary gear 21, pinions 26 and 26b, idlers 15 28 and gears 27 rotate the spindles 33 about their respect-ive~axes. Appropriate selection of the gear ratio~ insures that the ribs 35 of the spindles 33 will roll on the surface of the tube I0 without slipping, so that the cutter will progress aroun~ the tube in an epicycloidal path.
The helical ribs 35 on the spindles 33 will engage with the corrugations of the corrugated tube to advance the tube through the cutter. With a tube having helical corrugations such as that shown in Figure 7, the ribs 35 may be annular rather than helical. Helical ribs are required 25 for a pipe with annular corrugations.

Claims

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1. An apparatus for perforating a tube,including at least one punch mounted on and projected radially from at least one spindle spaced from and substantially parallel to said tube, the spindle being provided with a drive for rotating the spindle about its axis of rotation and simultaneously revolving the spindle about the tube in an epicycloidal path, to perforate the tube with said punch substantially without its tangential movement in relation to the tube.

2. The apparatus of Claim 1 characterized in that said spindle is provided with a helical rib for meshing engagement with the corrugations of the perforated tube to advance the latter axially.