GB2048748A - Rubber Tapping Instrument - Google Patents

Abstract

An instrument for tapping rubber trees comprising a hollow handle 40 within which is mounted a leadscrew 27 having a helical thread 42 which engages a pin 43 on the housing to cause the leadscrew to rotate as it is moved longitudinally. A puncturing needle 1 is attached at the outer end of the leadscrew 27 and a spring 28 biasses the leadscrew in outwards direction. <IMAGE>

Description

SPECIFICATION Rubber Tapping Instrument The present invention relates to an instrument for extracting latex from Hevea brasiliensis and other rubber latex bearing species.

The conventional method of tapping rubber trees is by the excision method whereby a thin layer of bark is pared away from a previously cut surface at each tapping. Two basic types of knife are used in the conventional method of tapping, and these are the pulling type (Jebong) and the pushing type (Gouge). Tapping is done either by pulling or by pushing the respective knives over a previously cut surface made in the bark of the tree. To obtain maximum latex yield, the tapping cut must be made as close as from about 0.5 to about 1.0 mm from the cambium layer of the bark. Any accidentai wounding cf the cambium results in undesirable, uneven renewal of bark, thereby rendering subsequent tapping more difficult. Such a conventional tapping operation is time consuming and demands a high degree of skill.Consequently, a skilled tapper can tap only 550 to 600 trees in a normal tapping day.

Recently, an incision technique known as micro or puncture tapping has been experimented with and has been shown, with chemical stimulation, to give yields comparable with conventional excision tapping (see Revue Gen Caoutel Plastig 50 (7-8): Tupy J. "Possibilite d'exploitation de l'Hevea par microsaignes"). Puncture tapping entails puncturing a series of holes, typically using a ca. 1.0 mm diameter needle, along a vertical strip or groove of scraped bark 80-100 cm long. To maintain the required level of latex yield, a latex stimulant is usually applied to the scraped bark. This puncture method of tapping can be performed very rapidly and requires little skill. The instrument used to effect tapping comprises a bradawl-like tool having a short needle removably attached to a handle.This tool, although convenient, has numerous shortcomings. In order to use the tool, the needle is pushed into the tree and thence retracted, this operation being repeated many times.over during tapping of a large number of trees. The double operation requires considerable effort and thus muscle fatigue sets in, typically after about one thousand punctures have been made. The present invention seeks to improve on the existing tools used for rubber tapping, particularly incision tapping.

In accordance with the invention there is provided a rubber tapping instrument comprising an elongate housing, a threaded leadscrew mounted for longitudinal and rotational motion within said housing, spring means acting on one end of the leadscrew for biassing the leadscrew in a longitudinal direction away from one end of the housing, a needle mounted on the other end of the leadscrew and extending longitudinally outside the housing, and means attached to said housing for engaging said leadscrew so that longitudinal pressure on the leadscrew via the needle results in the leadscrew being rotated as it moves longitudinally.

In order to use the known tool, the handle is gripped and the needle pushed into the bark. Since the needle must of necessity be fairly fine, frequent bending or breakage occurs in use, and it is therefore desirable to make the needle readily replaceable when it becomes damaged. Replacement of the needle in existing tools is slow and cumbersome. In one typical type a fastening nut has to be unscrewed with a screwdriver to remove the damaged needle. Sometimes the needle splinters inside the handle or becomes trapped in a coagulated pad of latex. A major further limitation is the diffusion of latex into the tool body causing corrosion and jamming of the needle.

In a preferred embodiment of the invention it is sought to overcome or reduce these problems by providing that the needle has a protruding portion extending away from the axis of the needle, said protruding portion being trapped by means of a collar fixed to said other end of the leadscrew, thereby mounting said needle on the end of the leadscrew. Preferably the protruding portion is positioned at or near one end of the needle, although it is conceivable that, for example, a central position could be chosen, thus providing a "double-ended" needle. The needle may be readily removed by releasing the collar and withdrawing the needle. In its simplest form, said protruding portion may be formed by enlarging the end of the needle, for example by flattening it, or by bending the end of the needle over to approximately a right angle.Alternatively, a disc or bar could be welded across the end of the needle to form said protruding portion. In a still further alternative, the end of the needle may be flattened to form a wedge.

The needle may take the form of a thin rod crudely cut off at its working tip. Such a tip, when rotated, will bite into the tree and considerably ease the effort required. Even if the needle has a straight cut-off tip, it is found that the pressure necessary is considerably lessened. In an embodiment of the invention, the needle takes the form of a conventional twist drill bit which, when rotated will readily puncture the bark with no tendency to jam upon its own waste material.

The instrument of this invention is operated by gripping the housing which can form a handle, then placing the top of the needle against the tree, and pushing the handle towards the tree to rotate the leadscrew and hence the needle. The spring means operates to return the leadscrew to its original position in the housing for subsequent puncturing operations.

As a matter of practice, it is found that the needles are subject to damage in the form of bending or breaking whilst they are being handled, but not actually in use. Accordingly, in an embodiment of the invention the needle is protected by a cap or nozzle which normally covers the needle, but which may be retracted or removed before or when the needle is pushed into the tree. Preferably the nozzle is spring loaded, the needle emerging (in use) through a small aperture provided in the end of the nozzle.

In an embodiment of the invention, the nozzle comprises a cylindrical member having a stepped bore defining a shoulder against which a spring abuts to bias the nozzle into a position in which it normally covers the needle. The needle itself is positioned coaxially within the cylindrical member and is such that its tip normally lies just behind the open end of the narrower portion of said stepped bore.

In a preferred embodiment, the end of the nozzle which, in use, is pushed against the tree to effect puncturing is shaped to conform with the shape of the tree itself. This ensures that the needle is inserted into the tree at the correct position and correct angle relative to the bark, which is an important factor in certain types of tapping. For example, this feature enables the instrument to be used not only for incision tapping but also for micro-excision tapping by the method described in our copending application 7,914,834.

In order that the invention may be better understood, several embodiments thereof will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is an exploded sectional side view of a first embodiment of a rubber tapping instrument according to the present invention Figures 2A and 2B are side views of a second embodiment of the invention showing, respectively, the tool with the needle exposed and the tool with the needle retracted; Figures 3A and 3B are views similar to Figures 2A and 2B respectively showing a third embodiment of the invention; Figures 4A and 4B are views similar to Figures 2A and 2B respectively showing a twin injector tool in accordance with the invention;; Figures 5A and 5B are respectively an exploded partial side view and a side view of a fourth embodiment of the invention; and Figures 6A, B and C show diagrammatically three forms of instrument nozzle useable in different situations.

Referring first to Figure 1 there is shown a rubber tapping instrument in which a needle 1 typically of 1 mm or thicker diameter steel wire, is rotated by means of a pump action mechanism operated by pushing a handle 7 towards the needle with the needle pushed against a tree. In this embodiment the handle 7 takes the form of a shaped wooden or plastics sheath which fits over one end of a hollow cylindrical body 24. The body is actually in the form of a stepped cylinder, with an upstanding flange 25 at the junction of the narrow and wide portions. The handle 7 is fitted over the right hand (narrower) end of the body and, when fitted, abuts the flange 25. A sleeve 26 fits over the left hand (wider) end of the body and protects certain of the moving parts of the mechanism.

The body contains an elongate leadscrew 27 which is rotatably and longitudinally movably mounted therein. A compression spring 28 biases the leadscrew in a leftwards direction, the spring 28 acting between a slotted end nut 29 and a plunger bearing 30. Leftwards movement is limited by the abutment of a circlip 31 against a bush 32. The bush 32 is non-rotatable, and is engageable with the leadscrew in such a way that the leadscrew, if caused to move longitudinally in relation to the body 24, will also rotate.

The outer end 33 of leadscrew 27 is threaded so as to be engageable in an internally threaded blind bore in an adaptor member 34. The adaptor member 34 has a further blind bore of larger diameter which is equipped with an internal BSW thread. A cylindrical collar 35 is externally threaded with a corresponding BSW thread so as to be threadedly engageable in the adaptor member.

The interior of the collar 35 carries a plunger 36 and nozzle 37. The needle 1 extends through the plunger 36 and has a bent-over end 6 whereby it may be trapped between the end of the plunger and the bottom of the larger blind bore in the adaptor member 34. A coil spring 38 positioned around the plunger 36 biasses the nozzle 37 in an outwards direction . so that, in its normal position, it covers and protects the needle 1. The needle may be readily replaced by unscrewing the collar 35 from the adaptor member 34 whereupon the needle may be removed and renewed or repaired.

In order to use the instrument shown in Figure 4, the tip of nozzle 37 is held at an angle to the vertical groove of the tapping cut whilst holding the handle 7, and the handle is pushed downwards to cause relative movement between the leadscrew 27 and the body 24. This causes the leadscrew, and hence the needle 1 to rotate, thus aiding the passage of the needle 1 into the tree. The needle is retracted from the tree by pulling in the usual way, aided by the action of spring 38.

It will be seen that the system provides a mechanical advantage and thus results in economy of effort. The automatic retraction of the instrument allows for puncture tapping to be reduced to one operation. Both these features speed up the process of tapping considerably and make tapping relatively simple with less fatigue. Field trials have shown that over 700 trees can be tapped in five hours. This is a substantial increase over the conventional number over the same period of 500 trees.

Referring now to Figure 2, there is shown a further embodiment of a rubber tapping tool. The tool comprises an elongate tubular body 40 in which is housed a leadscrew 27 which is rotatably and longitudinally movably mounted. The body 40 also contains compression spring 28 which acts between an end screw 41 and the left hand end of the leadscrew. The leadscrew has a thread in the form of a helical groove 42 which coacts with a pin 43 fixed to the body 40 in order to cause rotative motion of the leadscrew as it is moved longitudinally relative to the body. The outer end 44 of the leadscrew is threaded and carries an internally threaded collar 45. The collar has a narrow aperture extending therethrough in the longitudinal direction, which aperture carries the needle 1.The inner end of the needle 1 is bent over and is trapped between the threaded end of the leadscrew and the collar 45 in order to retain the needle. In an alternative embodiment (not shown) the outer end 44 of the leadscrew is formed with an axially extending blind bore which is internally threaded to receive the head of a threaded plastic map pin. Such a pin, which is readily available, may be readily removed if damaged and replaced by a new pin. A cap member 46 is used to cover the needle to protect same when the tool is not in use. In order to use the tool, the cap member may be removed, and fitted over the rear end of body 40 to act as a handle, as shown in Figure 2(A).

To prevent latex from diffusing into the tool body, the needle aperture in the collar 45 may be covered with a disc of rubber. Alternately, the rubber disc can be placed inside the collar. A further alternative is to use a teflon or nylon collar. An advantage of this is that the collar can be fitted direct to the leadscrew without a holder. To fit, the collar is screwed on to the leadscrew body. These alternative forms of collar shown in Figures 2C and 2D where reference 50 is the rubber disc.

Figure 3 illustrates a rubber tapping tool similar to that of Figure 2 but in which the outer cylindrical surface of the collar 45 is threaded so the cap member 46 can be threaded onto it. For this purpose, the cap member is internally threaded and has a small through-aperture at its pointed end 47 through which the needle 1 may protrude during use of the tool.

It will be seen in Figure 3 that only the outer part of the cap member is threaded, the inner part being smooth to act as a bearing surface with the outer surface of body 40 during use of the tool when the two surfaces slide with respect to one another. In order to use the tool, the cap member is screwed from the position shown in Figure 3(B), where it covers and protects needle 1 , to the position shown in Figure 3(A) in which the needle protrudes through the aperture in the end of the cap member.

Figure 4 is a view of a twin tapping tool which enables two punctures to be made simultaneously.

The tool effectively comprises two separate tools of the type shown with reference to Figure 2 mounted together within a common cylindrical housing 48. A common end cap 49 is used to protect the needles 2 when the tool is not in use (Figure 4B), but may be removed and fitted over the housing 48 to act as a handle during use of the tool (Figure 4A). The operation of the tool will be clear from the drawings and with reference to the description of Figure 2.

A still further embodiment of the invention is shown in Figure 5 to which reference will now be made. Figure 5 shows a compact ratchet instrument comprising two tubular bodies 51, 52 slidable telescopically within one another. The leadscrew 27 lies within the hollow interior of the two bodies and is biassed against a first 51 of these, acting as a handle, by means of the coil spring 28. It will be noticed that the spring 28 actually surrounds the leadscrew, resulting in a compact construction. The left-hand end 53 of the leadscrew is enlarged, and the spring acts between this enlarged end and the left-hand end of the other body 52, which takes the place of the collar 37/45 of earlier embodiments.

The needle 1 may be attached in any desired manner to the right-hand end of the leadscrew. A ballbearing 54 is positioned between the left-hand end of the leadscrew and the left-hand (closed) end of the body 51 and is retained in a central position by virtue of the provision of a circular seating in the enlarged end 53 of the leadscrew and by virtue of the bias of the spring 27, which keeps the leadscrew biassed in a leftwards direction. As with previous embodiments, the leadscrew is rotated as the two body parts 51, 52 are moved relative to one another in an axial direction by means of a- pin 43 which engages in the helical thread 42 of the leadscrew.

The two body parts 51, 52 are prevented from rotating relative to each other by virtue of the engagement of a pin 55 attached to the part 51 in an axially extending slot 56 cut in the part 52. The extent of slot 56 also defines the limits of movement of part 52 relative to part 51. The right hand end of slot 56 is cranked to define a locked position of the two parts when not in use. The slot also enables removal of part 52 in order to replace the needle.

The various instruments described herein can be used for any form of incision tapping of rubber.

They can also be used to make punctures for sampling yields or measuring the thickness of bark. The instruments can also be used for test tapping of nursery rubber. Finally the instruments described herein can be used to carry out the special method of micro-excision tapping described in our aforementioned application of even date.

Two examples ofthe trial use of the instrument of this invention will now be described.

Example 1 Half task size blocks of three cuitivars were selected for this experiment. The plots were tapped on conventional tapping and with the manual and automatic injectors. The trees were stimulated in November 1 978 and yields recorded for three months. The comparative yields are presented in grams per tree per tapping (g/t/t) in Table 1.

Table 1 Comparative Yields (g/t/t) Between Manual and Plunger-Type Injectors RRIM 600 RRlM7o3 RRlM6O5 RRIM 600 Treatment PanelA Panel B Panel C High Panel Conventional tapping 36.1 42.2 58.7 28.2 h6S/2D/2 (100) (100) (100) (100) 4P D/2 plus ethephon 42.7 52.1 64.2 42.7 stimulation with (118) (123) (109) (151) Manual injector 4P D/2 plus ethephon 42.7 54.2 67.1 42.4 stimulation with (118) (128) (115) (150) plunger-type injector (Figure 4) (Note: zS/2 D/2 refers to the half-spiral, alternate day tapping system; 4P D/2 refers to the 4puncture alternate day tapping system).

Table 2 Comparative Yields in KG/HA Task (No. of trees tapped) Treatment RRIM 703 RRIM 600 Kgltapper/3 months Conventional tapping 520 - 26.2 ',,S/2D/2 (100) (100) 4P D/2+E, with 600 602 32.9 - Manual injector (115) (100) (126) 4P D/2+E, with 70Q 698 36.2 21.2 Plunger-type (135) (116) (138) (100) injector Higher yields than conventional tapping without stimulation were obtained in all cases with puncture tapping methods. Good yields on high panels were obtained when puncture tapping. Yields were comparable as between the manual and plunger-type injector took 25% less time to complete as will be illustrated in the next example.

Example 2 For this experiment, a large block of RRIM 703 and RRIM 600 were selected and subdivided into various task sizes. The trees were stimulated and yields recorded for three months. The comparative yields and task size are given in Table 2.

The higher yields obtained are entirely consistent with the fact that the number of trees tapped can be increased substantially with the plunger-type injectors described herein.

It has already been mentioned that the end of the nozzle is preferably shaped in accordance with the tree itself. The shape can take several forms depending upon the quality of the bark being tapped and which of the various different tapping systems is to be used. Three of the shapes which have been found particularly favourable are shown in Figure 6, which is self-explanatory.

Claims (13)

Claims

1. A rubber tapping instrument comprising an elongate housing, a threaded leadscrew mounted for longitudinal and rotational motion within said housing, spring means acting on one end of the leadscrew for biassing the leadscrew in a longitudinal direction away from one end of the housing, a needle mounted on the other end of the leadscrew and extending longitudinally outside the housing, and means attached to said housing for engaging said leadscrew so that longitudinal pressure on the leadscrew via the needle results in the leadscrew being rotated as it moves longitudinally.

2. A rubber tapping instrument as claimed in claim 1, wherein the needle has a protruding portion extending away from the axis of the needle, said protruding portion being trapped by means of a collar fixed to said other end of the leadscrew, thereby mounting said needle on the end of the leadscrew.

3. A rubber tapping instrument as claimed in claim 2, wherein the collar is screw threaded onto the end of the leadscrew and wherein said bent-over end of the needle is trapped between the collar and the end of the leadscrew to be retained thereby.

4. A rubber tapping instrument as claimed in claim 2, wherein the collar is hollow and houses a plunger which carries the needle and a spring which biases the plunger against the interior of the collar in such a way that the bent-over end of the needle is trapped and retained between the plunger and the interior of the collar.

5. A rubber tapping instrument as claimed in any one of the preceding claims, wherein the needle takes the form of a length of wire.

6. A rubber tapping instrument as claimed in any one of claims 1 to 4 wherein the needle takes the form of a twist drill bit.

7. A rubber tapping instrument as claimed in any one of the preceding claims further including a cap which is positioned to protect the needle when the instrument is not in use.

8. A rubber tapping instrument as claimed in claim 7, wherein said cap takes the form of a nozzle through which said needle may protrude, said nozzle being longitudinally movable and spring biassed so as to normally cover and protect said needle, the arrangement being such that, when pressure is applied to said nozzle, during use of the instrument, the nozzle retracts against said spring bias and uncovers the needle.

9. A rubber tapping instrument as claimed in claim 7, wherein said cap is a push fit over the housing and may thence be pushed over said one end of the housing to act as a handle while the instrument is in use, and may be pushed over the opposite end of the housing to protect the needle when the instrument is not in use.

10. A rubber tapping instrument as claimed in claim 7, wherein said cap is fixedly attached to the leadscrew in such a way that it can be moved relative thereto in order to cover the needle when the instrument is not in use or to allow the needle to protrude therefrom when in use.

1 i. A rubber tapping instrument as claimed in claim 10, wherein the cap is fixed to the leadscrew by screwthreading, the arrangement being such that rotation of the cap relative to the leadscrew will uncover the needle for use.

12. A rubber tapping instrument substantially as hereinbefore described with reference to the accompanying drawings.

13. A rubber tapping instrument for simultaneously making two adjacent tappings, said instrument comprising two rubber tapping instruments of the type claimed in any one of the preceding claims mounted in a common housing.