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An inexpensive hand-operated device for cutting core liners
Marine Geology, 70 (1986) 3 0 7 - - 3 1 1
307
Elsevier Science Publishers B.V., A m s t e r d a m - - Printed in The Netherlands
Letter Section An inexpensive hand-operated device for cutting core liners TAPAS KUMAR MALLIK
Marine Science Division, Centre for Earth Science Studies, Sasthamangalam, Trivandrum 695 010, KeraUa (India) (Received S e p t e m b e r 27, 1985; revised and accepted D e c e m b e r 3, 1985)
ABSTRACT Mallik, T.K., 1986. An inexpensive hand-operated device for cutting core liners. Mar. Geol., 70: 307--311. A simple h a n d - o p e r a t e d device for cutting longitudinal sections o f core liners has been developed at a very low cost. The liner is placed on a stand and secured properly by circular plates and tightening levers. T w o high-speed steel blades situated in diametrically opposite direction are pressed tightly o n the liner. By rotating a handle these blades m o v e to cut b o t h sides of the liner simultaneously. For cross-sectioning the core liner another simple hand-operated i n s t r u m e n t has been illustrated. The liner is fixed in a stationary ring by tightening screws. An adjustable lever with a high-speed steel blade is fixed on a t o o l holder and welded to an o u t e r ring which is r o t a t e d 180 ° by a handle to cut the liner. The cut p o r t i o n s are s m o o t h , perfect and straight and the o p e r a t i o n is very simple and safe.
INTRODUCTION
As a part of geological investigations of the Marine Science Division of the Centre for Earth Science Studies, Trivandrum, a number of short gravity cores were collected from the shallow portion of the inner-shelf areas off Kerala coast, India. High-impact PVC tubes were directly used in place of a core barrel by threading both ends as shown at A in Fig. 1. The cores obtained are retained inside the PVC tubes, after detaching those from the main corer unit. For working in shallow areas and in estuaries the corer operated rather successfully. It was very convenient to preserve the core in the tube which could be removed easily. Loss of the cutting edge, usually resulting from accidental breaking of the tube, was avoided by tieing a nylon thread from the central joint of the corer to the cutting edge as shown at B in Fig. 1. However, different problems were faced while cutting the PVC tubes with a hacksaw on board ship as well as in the laboratory. This problem was solved by developing a simple, inexpensive, hand-operated, core-cutting machine. Details are presented in later sections. For cross-sectioning of the core liners a separate instrument is used, which is also described in the later part.
0025-3227/86/$3.50
© 1986 Elsevier Science Publishers B.V.
308
Fig. 1. Gravity corer w i t h t h e core barrel replaced by h i g h - i m p a c t PVC t u b e (A). Loss o f t h e c u t t i n g edge is avoided by tieing a t h i n n y l o n r o p e (B) f r o m the cutting edge t o the central joint. Fig. 2. A view o f t h e m a c h i n e for longitudinal c u t t i n g o f core liner. A = pipe rest stand; B = core t u b e ; C = circular plate; D = fixed h o l l o w t u b e ; E = t i g h t e n i n g lever and c l a m p sliding o n the rack.
309
PREVIOUS WORK
Core liners are cut by a number of methods. Rusnak and L u f t {1963, quoted in Bouma, 1969) used a hand-operated saw to cut the core liner. The liner can be cut with a hacksaw, by an electrically operated rotating blade, or by moving a saw by a m o t o r along a straight line as used on board the "Glomar Challenger". Rock-cutting machines have also been used to cut the liners. The soft core can be cut by a piano wire, spatula, normal knife, razor blade or by Chemlik's (1967) electroosmotic knife. Some details have been reviewed in Bouma (1969). PRESENT DESIGN
The present design for longitudinal cutting and cross-sectioning of the core liners are very simple. The units are inexpensive costing only Rs. 2800,(US $233) and safe to handle. Different views of the machines and cutting procedures are shown in Figs. 2--7.
Longitudinal cutting o f core liners A V-shaped pipe-rest stand (A in Fig. 2) on four legs, made from mild steel, forms the main frame of the machine on which the core liner (B) is placed for cutting. A fixed circular plate (C), containing two diametrically opposite small horizontal slits just little more than the wall thickness of the tubes in length, is m o u n t e d at one end of the stand. The diameter of this plate is equal to the outer diameter of the core tube and is fixed to a hollow pipe (D). One end of the core liner rests against this circular plate. Another circular plate exactly similar to plate (C) is connected to a tightening lever (E) that slides on the rack which can be screwed by a clamp to fix the other end of the core liner tightly. Depending on the core length the position of Fig. 3. Enlarged view o f t h e u p p e r left p o r t i o n s h o w i n g p o s i t i o n o f circular plate (C), h o l l o w t u b e (D), a d j u s t a b l e lever (F), high-speed steel b l a d e (G), a n d fly n u t (J). Fig. 4. C u t t i n g o f core liner in progress. Moving r a c k (H) a n d driving h a n d l e (I) are clear. T h e a r r o w at K o n t h e l e f t - h a n d side i n d i c a t e s p o s i t i o n o f t h e h o r i z o n t a l slit f r o m w h e r e c u t t i n g has s t a r t e d . Fig. 5. L o n g i t u d i n a l c u t t i n g o f core liner in progress. A r r o w a t K a n d L i n d i c a t e p o s i t i o n o f h o r i z o n t a l slits. T h e core will b e c u t along t h e line K--L. Fig. 6. D i f f e r e n t p o r t i o n s o f t h e core liner cross-sectioning device w i t h a liner. A = stat i o n a r y r i n g ; B = t i g h t e n i n g screw; D = o u t e r guide ring; E = fixed screws f o r r o t a t i o n ; G = high-speed steel b l a d e ; H = t o o l h o l d e r . Fig. 7. Full view o f t h e cross-sectioning m a c h i n e . C = fixed s t a n d , F = t o o l a d j u s t a b l e handle.
310 the tightening lever and circular plate will be adjusted. After fixing in this way the liner tube will not move and is ready for cutting. An enlarged view of the left half of the instrument is shown in Fig. 3. There is an adjustable lever i F) with high speed steel blades (G); the position of the steel blades is to be initially guided by the small slits cut on either side into the fixed circular plate (C). The position of the slit is shown by arrows in Fig. 4 at K and in Fig. 5 at K and L. The adjustable lever with the steel blades moves over a rack (H in Fig. 4) with the help of three gear wheels that are operated by a driving handle (I) similar to the ones used in a lathe. The positions of the blades are adjusted before operating the driving handle. The blades are moved inward by turning the fly nuts (J, Figs. 3 and 4) so that they press tightly to the tube to allow a gradual cut when the handle is rotated (shown in Fig. 5). The blade on either side is to be placed at slit K prior to the cutting operation. The handle is rotated in clockwise direction till the blades reach the end of the tube. A cutting mark will be left on the tube. After that the blades are again brought to the initial position by rotating the handle in anticlockwise direction. This operation, and adjustment of the blades, is repeated three or four times till both blades just cut the liner simultaneously. After the liner is cut, the usual procedure can be followed for cutting the sediments inside. The present machine was designed for cutting core liner lengths of 1 m, but such can be increased easily. The performance of the equipment has been very fine. After long use only the blades should be replaced. PRECAUTIONS Before cutting the tube one have to be sure that the slits in the circular plates for tightening the liner are properly aligned. This prevents damage to the blade at the end. Instead of cutting the entire thickness by one run, it is recommended that the cutting operation is performed by repeating the operation a few times. The blades have to be cleaned properly after the use. Cross-sectioning of the core liner For making a cross-cut, the liner can be placed in the core cross-sectioning device (Figs. 6 and 7). This is a sophisticated modification of a can cutter. The machine consist of a circular stationary inner ring CA, Fig. 6) which holds the core-liner tube tightly by means of three tightening screws (B). This ring is welded to a fixed stand (C, Fig. 7) which can be used for securing the ring to any fixed object. The diameter of the inner ring is slightly larger than the diameter of the liner. There is an outer guide ring (D) which moves freely about the inner ring. The movement is achieved via a small circular groove on the outer side of the stationary ring into which three screws {E) just enter loosely. An adjustable lever, housing high speed steel blades, (G)
311
is fixed in a tool holder (H). An adjustable handle {F); {Fig. 7) gives the cutting depth of the blades. By rotating the handle the adjustable lever moves and tightly presses the liner. The handle in this position can be easily rotated 180 ° with the outer ring to achieve the cutting. The blade can be adjusted each time by pushing inside and turning the handle to preserve tight contact with the tube. By repeating the operation two or three times the liner can be cut very smoothly. ADVANTAGES
(1) The above described instruments are very simple, inexpensive, and are safe to handle. (2) The longitudinal cuts are smooth, perfect and both ends of the core liner are cut simultaneously. (3) The cross-cut sections of the core liners are smooth and straight. ACKNOWLEDGEMENT
The author is grateful to Dr. Harsh K. Gupta, Director, Centre for Earth Science Studies, Trivandrum, for encouragement and for the various facilities. Mr. Sebastian Cross, Managing Partner, M/s. J & B Engineering Lathe Works, Kochu Velu, Trivandrum, and his staff fabricated the equipment.
REFERENCES Bouma, A.H., 1969. Methods for the Study of Sedimentary Structures. Wiley, New York, N.Y., 458 pp. Chemlik, F.B., 1967. Electro-osmotic core cutting. Mar. Geol., 5 : 321--325.
307
Elsevier Science Publishers B.V., A m s t e r d a m - - Printed in The Netherlands
Letter Section An inexpensive hand-operated device for cutting core liners TAPAS KUMAR MALLIK
Marine Science Division, Centre for Earth Science Studies, Sasthamangalam, Trivandrum 695 010, KeraUa (India) (Received S e p t e m b e r 27, 1985; revised and accepted D e c e m b e r 3, 1985)
ABSTRACT Mallik, T.K., 1986. An inexpensive hand-operated device for cutting core liners. Mar. Geol., 70: 307--311. A simple h a n d - o p e r a t e d device for cutting longitudinal sections o f core liners has been developed at a very low cost. The liner is placed on a stand and secured properly by circular plates and tightening levers. T w o high-speed steel blades situated in diametrically opposite direction are pressed tightly o n the liner. By rotating a handle these blades m o v e to cut b o t h sides of the liner simultaneously. For cross-sectioning the core liner another simple hand-operated i n s t r u m e n t has been illustrated. The liner is fixed in a stationary ring by tightening screws. An adjustable lever with a high-speed steel blade is fixed on a t o o l holder and welded to an o u t e r ring which is r o t a t e d 180 ° by a handle to cut the liner. The cut p o r t i o n s are s m o o t h , perfect and straight and the o p e r a t i o n is very simple and safe.
INTRODUCTION
As a part of geological investigations of the Marine Science Division of the Centre for Earth Science Studies, Trivandrum, a number of short gravity cores were collected from the shallow portion of the inner-shelf areas off Kerala coast, India. High-impact PVC tubes were directly used in place of a core barrel by threading both ends as shown at A in Fig. 1. The cores obtained are retained inside the PVC tubes, after detaching those from the main corer unit. For working in shallow areas and in estuaries the corer operated rather successfully. It was very convenient to preserve the core in the tube which could be removed easily. Loss of the cutting edge, usually resulting from accidental breaking of the tube, was avoided by tieing a nylon thread from the central joint of the corer to the cutting edge as shown at B in Fig. 1. However, different problems were faced while cutting the PVC tubes with a hacksaw on board ship as well as in the laboratory. This problem was solved by developing a simple, inexpensive, hand-operated, core-cutting machine. Details are presented in later sections. For cross-sectioning of the core liners a separate instrument is used, which is also described in the later part.
0025-3227/86/$3.50
© 1986 Elsevier Science Publishers B.V.
308
Fig. 1. Gravity corer w i t h t h e core barrel replaced by h i g h - i m p a c t PVC t u b e (A). Loss o f t h e c u t t i n g edge is avoided by tieing a t h i n n y l o n r o p e (B) f r o m the cutting edge t o the central joint. Fig. 2. A view o f t h e m a c h i n e for longitudinal c u t t i n g o f core liner. A = pipe rest stand; B = core t u b e ; C = circular plate; D = fixed h o l l o w t u b e ; E = t i g h t e n i n g lever and c l a m p sliding o n the rack.
309
PREVIOUS WORK
Core liners are cut by a number of methods. Rusnak and L u f t {1963, quoted in Bouma, 1969) used a hand-operated saw to cut the core liner. The liner can be cut with a hacksaw, by an electrically operated rotating blade, or by moving a saw by a m o t o r along a straight line as used on board the "Glomar Challenger". Rock-cutting machines have also been used to cut the liners. The soft core can be cut by a piano wire, spatula, normal knife, razor blade or by Chemlik's (1967) electroosmotic knife. Some details have been reviewed in Bouma (1969). PRESENT DESIGN
The present design for longitudinal cutting and cross-sectioning of the core liners are very simple. The units are inexpensive costing only Rs. 2800,(US $233) and safe to handle. Different views of the machines and cutting procedures are shown in Figs. 2--7.
Longitudinal cutting o f core liners A V-shaped pipe-rest stand (A in Fig. 2) on four legs, made from mild steel, forms the main frame of the machine on which the core liner (B) is placed for cutting. A fixed circular plate (C), containing two diametrically opposite small horizontal slits just little more than the wall thickness of the tubes in length, is m o u n t e d at one end of the stand. The diameter of this plate is equal to the outer diameter of the core tube and is fixed to a hollow pipe (D). One end of the core liner rests against this circular plate. Another circular plate exactly similar to plate (C) is connected to a tightening lever (E) that slides on the rack which can be screwed by a clamp to fix the other end of the core liner tightly. Depending on the core length the position of Fig. 3. Enlarged view o f t h e u p p e r left p o r t i o n s h o w i n g p o s i t i o n o f circular plate (C), h o l l o w t u b e (D), a d j u s t a b l e lever (F), high-speed steel b l a d e (G), a n d fly n u t (J). Fig. 4. C u t t i n g o f core liner in progress. Moving r a c k (H) a n d driving h a n d l e (I) are clear. T h e a r r o w at K o n t h e l e f t - h a n d side i n d i c a t e s p o s i t i o n o f t h e h o r i z o n t a l slit f r o m w h e r e c u t t i n g has s t a r t e d . Fig. 5. L o n g i t u d i n a l c u t t i n g o f core liner in progress. A r r o w a t K a n d L i n d i c a t e p o s i t i o n o f h o r i z o n t a l slits. T h e core will b e c u t along t h e line K--L. Fig. 6. D i f f e r e n t p o r t i o n s o f t h e core liner cross-sectioning device w i t h a liner. A = stat i o n a r y r i n g ; B = t i g h t e n i n g screw; D = o u t e r guide ring; E = fixed screws f o r r o t a t i o n ; G = high-speed steel b l a d e ; H = t o o l h o l d e r . Fig. 7. Full view o f t h e cross-sectioning m a c h i n e . C = fixed s t a n d , F = t o o l a d j u s t a b l e handle.
310 the tightening lever and circular plate will be adjusted. After fixing in this way the liner tube will not move and is ready for cutting. An enlarged view of the left half of the instrument is shown in Fig. 3. There is an adjustable lever i F) with high speed steel blades (G); the position of the steel blades is to be initially guided by the small slits cut on either side into the fixed circular plate (C). The position of the slit is shown by arrows in Fig. 4 at K and in Fig. 5 at K and L. The adjustable lever with the steel blades moves over a rack (H in Fig. 4) with the help of three gear wheels that are operated by a driving handle (I) similar to the ones used in a lathe. The positions of the blades are adjusted before operating the driving handle. The blades are moved inward by turning the fly nuts (J, Figs. 3 and 4) so that they press tightly to the tube to allow a gradual cut when the handle is rotated (shown in Fig. 5). The blade on either side is to be placed at slit K prior to the cutting operation. The handle is rotated in clockwise direction till the blades reach the end of the tube. A cutting mark will be left on the tube. After that the blades are again brought to the initial position by rotating the handle in anticlockwise direction. This operation, and adjustment of the blades, is repeated three or four times till both blades just cut the liner simultaneously. After the liner is cut, the usual procedure can be followed for cutting the sediments inside. The present machine was designed for cutting core liner lengths of 1 m, but such can be increased easily. The performance of the equipment has been very fine. After long use only the blades should be replaced. PRECAUTIONS Before cutting the tube one have to be sure that the slits in the circular plates for tightening the liner are properly aligned. This prevents damage to the blade at the end. Instead of cutting the entire thickness by one run, it is recommended that the cutting operation is performed by repeating the operation a few times. The blades have to be cleaned properly after the use. Cross-sectioning of the core liner For making a cross-cut, the liner can be placed in the core cross-sectioning device (Figs. 6 and 7). This is a sophisticated modification of a can cutter. The machine consist of a circular stationary inner ring CA, Fig. 6) which holds the core-liner tube tightly by means of three tightening screws (B). This ring is welded to a fixed stand (C, Fig. 7) which can be used for securing the ring to any fixed object. The diameter of the inner ring is slightly larger than the diameter of the liner. There is an outer guide ring (D) which moves freely about the inner ring. The movement is achieved via a small circular groove on the outer side of the stationary ring into which three screws {E) just enter loosely. An adjustable lever, housing high speed steel blades, (G)
311
is fixed in a tool holder (H). An adjustable handle {F); {Fig. 7) gives the cutting depth of the blades. By rotating the handle the adjustable lever moves and tightly presses the liner. The handle in this position can be easily rotated 180 ° with the outer ring to achieve the cutting. The blade can be adjusted each time by pushing inside and turning the handle to preserve tight contact with the tube. By repeating the operation two or three times the liner can be cut very smoothly. ADVANTAGES
(1) The above described instruments are very simple, inexpensive, and are safe to handle. (2) The longitudinal cuts are smooth, perfect and both ends of the core liner are cut simultaneously. (3) The cross-cut sections of the core liners are smooth and straight. ACKNOWLEDGEMENT
The author is grateful to Dr. Harsh K. Gupta, Director, Centre for Earth Science Studies, Trivandrum, for encouragement and for the various facilities. Mr. Sebastian Cross, Managing Partner, M/s. J & B Engineering Lathe Works, Kochu Velu, Trivandrum, and his staff fabricated the equipment.
REFERENCES Bouma, A.H., 1969. Methods for the Study of Sedimentary Structures. Wiley, New York, N.Y., 458 pp. Chemlik, F.B., 1967. Electro-osmotic core cutting. Mar. Geol., 5 : 321--325.