CA1283278C - Thermoplastic block shape feeding mechanism and manufacturing method - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A block of solid thermoplastic material comprising alternating sections of circular and rectangular cross section, a device for melting and dispensing thermoplastic material having a thumb operated ratchet assembly for driving the block into the device, and a molding mechanism including two chain like structures that move along linear path portions with molds included in the structures in face to face relationship while molten thermoplastic is injected in an inlet end of the linear path portion to continuously mold the block.

Description

- 1 - 605~7-3107 This application relates to devices for dispensing molten thermoplastic materials into which blocks of solid thermo-plastic material are pressed by the thumb of the user's hand, shapes for blocks of solid thermoplastic material to be dispensed in such a device, and methods for making the blocks.
Many devices are known for dispensing molten thermo-plastic materials from blocks of solid thermoplastic material pressed into the device b~ the thumb of the user's hand, such as the prior art devices described in United States Patents Nos.
3,204,828 ~nd 3,298,572.
Generally, such devices comprise a barrel member having an internal melting chamber which communicates with an outlet opening through a nozzle, and a sleeve with a through opening having one end secured to the barrel member with its through opening communicating with the end of the melting chamber opposite the nozzle. The sleeve is adapted to receive an elon-gate cylindrical block of solid thermoplastic material which fits closely within the through opening in the sleeve, with one end portion of the block in the melting chamber and the other end portion projecting through the sleeve. Means are provided for heating the barrel member to melt the end portion of the block therein, and the device includes a handle positioned so that an operator can grip the handle with the fingers of A

7~

one hand while pressing the block through the sleeve and into the melting chamber with the thumb of that hand to force molten thermoplastic material out of the melting chamber through the nozzle.
While such devices function effectively and provide great versatility in regulating the amount of thermoplastic material flowing through the devices, a problem can occur after the operator places a second block of thermoplastic material end to end with the block in the 10 sleeve and presses on the outer end of the second block. The operator must hold the second block in place, thus occupying the operator's second hand which may be needed elsewhere such as to manipulate articles to which the molten thermoplastic material is being applied. If the operator 15 does not hold the second block in place and releases the pressure on the second block as must be done to stop the flow of the molten thermoplastic material, or applies pressure in some direction other than axially along the second block before its leading end enters the sleeve, the 20 second block can fall or fly away from the block already in the sleeve, which is inconvenient, distracting, and wasteful of the operator's time.
A device for dispensing molten thermoplastic material described in my U.S. Patent No. 4,552,287 provides, 25 among other things, means for holding and properly positioning a second block of solid thermoplastic material at the end of a block of that material already in a sleeve and a melting barrel of a device of the type described above, even before the second block enters the outer end of 30 the sleeve, thereby freeing the use of the operator's second hand for other activities.
That device, however, will hold a maximum of less than three blocks of thermoplastic material, and thus frequent loading of the device is required if the device is 35 used continuously.

Our Canadian Patent Application No. ~71,893, describes a magazine assembly for use with the device described in my United States Patent ~o. 4/552~287. The magazine assembly provides means for holding and properly positioning a lowermost block of thermo-plastic material in aligned end-to-end relationship with a block of thermoplastic material wi-thin the sleeve while affording use of the operator's thumb to press the lowermost block through the sleeve and into the melting chamber and holding a stack of blocks of thermoplastic material normally above the lowermost block.
The stack of blocks can be caused to drop down to position the next lowermost block in alignment with the remainder of a block of thermoplastic material that has been pressed through the sleeve by reciprocal movement of a thumb operated slide which provides both a pusher for the lowermost block and a support for the stack of blocks above the lowermost blocks. While this magaæine assem-bly can be easi~y operated and holds a relatively large amount of thermoplastic material, it is more bulky than may be desired and must be loaded with a plurality of relatively small thermoplastic blocks.
Disclosure of the Invention The present inventions provide a new novel shape for a block of solid thermoplastic material that can more easily be melted and dispensed through a dispensing device of the type described above than cylindrical blocks of thermoplastic, a feed-ing mechanism adapted for use on a dispensing device of the type described above that is operated by the thumb of a user's hand, - 4 - 60557~3107 SDB;hmb cooperates with the new block shape and, while being very compact, allows very long blocks of the new shape to be easily fed into the dispensing device to minimize loading time, and a simple and efficient manufacturin~ device and method for manufacturing the new block.
More specifically, the present invention provides a device adapted for dispensiny molten, thermoplastic material from a block of the solid thermoplastic material comprising coaxial generally cylindrical portions of uniform predetermined axial and diametrical dimensions uniformly axially spaced along the block by rectangular portions having diagonal dimensions about equal to said diametrical dimension, said device comprising a frame including a handle positioned so that an operator can grip the handle with the fingers of one hand; a barrel member mounted on said frame and having an internal melting chamber communicating with an outlet opening through a nozzle; a sleeve with a through opening having one end secured to said barrel member with said through opening communicating with the end of said melting chamber opposite said outlet opening, said sleeve being adapted to receive a said block of solid thermoplastic material with one end portion of the block in the melting chamber and the block projecting through said sleeve; means for heating said barrel member to melt the end portion of the block therein; and a feeding mechanism at the end of said sleeve opposite said melting chamber comprising wall means fixed to said frame and defining a passageway adapted to guide the solid thermoplastic material block in alignment with the through opening in said sleeve, a slide having an upper surface positioned adjacent said passageway, and being mounted on - 4a - 60557-3107 SDB:hmb said ~rame for movement along a path generally aligned with the melting chamber from a retracted position spaced from said sleeve to an advanced position more closely adjacent the sleeve and back to said retracted position, drive means carried by said slide adapted for engaging said cylindrical portions and advancing the block of thermoplastic material toward the melting chamber during movement of said slide from its retracted to its advanced position, and for moving around the cylindrical portions and along the block of thermoplastic during movement of said slide from its advanced to its retracted position/ means for aligning the block of thermoplastic in said passageway for engagement by said drive means, and means projecting from the side of said slide opposite said upper surface in a direction generally at a right angle to said upper surface including a first projecting part adjacent said sleeve and a second projecting part spaced from the side of said first projecting part opposite said sleeve for defining a recess between said first and second parts adapted to receive the end portion of the thumb of an operator gripping said handle to afford manual movement of said slide both toward said advanced position and toward said retracted position.
In a further aspect, the invention provides a combination of a block of solid thermoplastic material comprising coaxial generally cylindrical portions of uniform predetermined, axial and diametrical dimensions uniformly axially spaced along the block by rectangular portions having diagonal dimensions about equal to said diametrical dimension; with a device of the type described in the preceding paragraph.
In another aspect, the invention is directed to a 3;~78 - 5 - 60557-3107 SUB:hmb feeding mechanism of the type described above which is a~apted for use on a device for dispensing molten, thermoplastic material.
The feeding mechanism of the invention while being very compact, affords feeding the novel shaped blocks of thermoplastic having the novel shape described above that can have a significantly greater length than commercially available cylindrical blocks (e.g. from two inches to over twelve feet long) so that time lost , c ",r 7~

- ~c~ - 60557-3107 loading the device is minimized.
Thermoplastic blocks of the shape described above are quite flexible compared to cylindrical blocks so that they can be coiled for storage ~e.g., in 50 centimeter diameter coils).
Also, it requires less force to feed thermoplastic blocks of the new shape into the device than it does to feed cylindrical blocks of thermoplastic into the device for the same output of melted thermoplastic material; apparently because the cavities around the periphery of the block between its cylindrical portions pro-vide receptacles for melted thermoplastic material and allow the solid thermoplastic material to be pressed more directly into contact with the heated barrel member.
Thermoplastic blocks of the new shape may be easily formed in a mechanism comprising two chain like structures each comprising a plurality of pivotably interconnected block like moulds, which when face to face define a cavity having the shape of the block therebetween, means for moving each of the chain like structures around a separate path with some blocks along the chain like structures moving in face to face contact along a lin-ear path portion, and means for injecting molten thermoplastic material into one end of the cavity defined between the '7~

molds along the linear path portion. Also a mechanism can be provided for cutting the block into predetermined lengths as it emerges from the molds.

_ ef Description of the Drawing The present invention will be further described with reference to the accompanying drawing wherein like reference numerals refer to like parts in the several views, and wherein:
Figure 1 is a side view of a first embodiment of a dispensing device described in my U.S. Patent No.
4,552,287;
Figure 2 is a side view of the dispensing device of Figure 1 having parts broken away to show details;
Figure 3 is an enlarged fragmentary sectional view of a barrel member, a sleeve, and a barrier ring therebetween in the dispensing device of Figure l;
Figure 4 is an enlarged sectional view taken approximately along lines 4-4 of Figure 2; and Figure 5 is an end view of the dispensing device of Figure l;
Figure 6 is a perspective view of a block of solid thermoplastic material hàving a shape according to the present invention;
Figure 7 is a side view of a dispensing device which is similar to the device of Figure 1 except that it includes a different manually operable feeding mechanism according to the present invention for feeding blocks of solid thermoplastic material of the type shown in Figure 6;
Figure 8 is an enlarged sectional view taken approximately along line 8-8 of Figure 7;
Figure 9 is an enlarged fragmentary view of a slide and drive means in the dispensing device of Figure 7 being used to press a block of solid thermoplastic material into the device;
Figure lO is an enlarged fragmentary view of the slide and drive means shown in Figure 9 being retracted 3;~

along a block of solid thermoplastic material in the device;
Figure 11 is a fragmentary plan view of a mechanism according to the present invention for making 5 blocks of thermoplastic material having the shape of the block shown in Figure 6;
Figures 12 and 13 are enlarged fragmentary views of inlet and outlet ends respectively of the mechanism shown in Figure 11, which mechanism has parts broken away and 10 removed to show details;
Figure 14 is an enlarged fragmentary sectional view taken approximately along line 14-14 of Figure 12;
Figure 15 is an enlarged fragmentary sectional view taken approximately along line 15-15 of Figure 13; and Figure 16 is an end detail view of one of a plurality of molds included in the mechanism shown in Figures 11 through 16;
Figure 17 is a plan view of a mechanism according to the present invention for cutting blocks of thermoplastic 20 material made by the mechanism shown in Figures 11 through 16;
Figure 18 is an enlarged fragmentary sectional view of the mechanism shown in Figure 17; and Figure 19 is a fragmentary sectional view taken 25 approximately along line 19-19 of Figure 18.

The Description of the Preferred Embodiment Referring now to the drawing there is shown in Figures 1 through 5 a dispensing device for molten 30 thermoplastic material generally designated by the reference numeral 10, which device 10 is described, using the same reference numerals from column 2, line 55 to column 8, line 4 of my U.S. Patent No. 4,552,2887.
Like known prior art dispensing devices for 35 thermoplastic material, the dispensing device 10 comprises a two part frame 12, a barrel member 14 mounted between the t;i~

parts of the frame 12 and having an internal melting chamber 16 communicating via a discharge passageway 17 through a valve assembly 18 with an outlet opening 19 through a nozzle 21, and a sleeve 20 with a cylindrical through opening 22 having one end secured to the barrel member 14 with its through opening 22 communicating with the end of the melting chamber 16 opposite the discharge passageway 17. ~he sleeve 20 is adapted to receive a cylindrical block 24 of solid thermoplastic material within the cylindrical through opening 22 with a slight clearance fit even when the diameter of the block 24 is at the large end of its tolerance range, with one end portion of the block 24 in the melting chamber 16 and the block 24 projecting through the opening 22 in the sleeve 20. Means are provided in the device 10 for heating the barrel member 14 to melt the end portion of the block 24 therein. The frame 12 includes a handle 26 positioned so that an operator can grip the handle 26 with the fingers of one hand while applying pressure with the thumb of that hand to press the block 24 through the sleeve 20 and into the melting chamber 16 and force molten thermoplastic material out of the melting chamber 16 through the valve assembly 18 and nozzle 21.
Unlike known prior art devices, the device 10 further includes a bracket assembly 28 at the end of the sleeve 20 opposite the barrel member 14, which bracket assembly 28 includes means adapted for receiving and for holding a second block 24 of solid thermoplastic material in aligned end-to-end relationship with the block 24 of thermoplastic material in the sleeve 20 while affording the application of force by the thumb of an operator on the end of the block 24 opposite the sleeve 20 to press the second block 24 through the sleeve 20 and into the melting chamber 16.
As illustrated, the bracket assembly 28 comprises spaced opposed gripping parts 30 of the frame 12 (Figure 5) that project toward the handle 26 in a position spaced from 7~

the outer en~ of the sleeve 20 and on opposite sides of an extension of the axis for the sleeve 20. The gripping parts 30 are biased toward each other by spring means comprising a channel-like member 29 of spring steel engaged around the top surfaces of the two parts of the frame 12 to help hold the two parts cf the frame 12 together, and having opposed arcuate projecting portions 27 that are biased against the outer surfaces on the gripping parts 30 of the frame 12.
The gripping parts 30 have distal ends spaced at a distance that i3 less than the diameter of the cylindrical block 24 of thermoplastic material, but which distance is sufficient so that the block 24 can be transversely pressed there-between to resiliently move the gripping parts 30 away from each other in opposition to the biasing of the projecting lS portions 27 and afford movement of the block 24 there-between. Also, the gripping parts 30 have concave opposed inner surfaces adapted to conform to and engage the cylindrical.side surfaces of a block 24 of thermoplastic material therebetween to hold the block 24 in alignment with a block 24 in the sleeve 20, while affording axial sliding movement of the block 24 and movement of the thumb of the operator between the gripping parts 30 to move the second block 24 into the sleeve 20.
The device also comprises a pressure plate 32 adapted to abut the end of the outermost block 24 of thermoplastic material opposite the melting chamber 16 and to be positioned between the block 24 and the user's thumb to transfer force therebetveen. The plate 32 includes an elongate slide portion 33 (Figure 2) at one edge slideably mounted in a track 34 defined between the parts of the frame 12 to afford movement of the plate 32 with the block 24 and is shaped to pasq between the gripping parts 30 so that the plate 32 can be used to push the block 24 fully into the sleeve 20 while directing forces applied to the plate 32 in the longitudinal direction of the block 24, and protects an operator's thumb from contact with the thermoplastic block 24 and from contact with any molten 7~

thermopla~stic material that (under unusual conditions) might extrude to the outer end of the sleeve 20. The pressure plate 32 includes two wing portions 35, one projecting from each side, which wing portions 35 are 5 positioned tc pass under the gripping parts 30 as the pressure plate 32 is used to presR the block 24 into the sleeve 20, and either of which wing portions 35 can be manually engaged to move the pressure plate 32 away from the sleeve 20 to facilitate placing a new block 24 of lO thermoplastic material between the gripping parts 30 after a previous block 24 has been pushed into the sleeve 20~
The two parts of the frame 12 are molded of a suitable high temperature resistant polymeric material (e.g., the materi-al commercially designated Dupon, Zytel 15 FR50-NC10 available from E. I. DuPont deNemours, Wilmington, Delaware). Both parts of the frame 12 are formed with spaced posts 36 projecting generally radially outwardly of the barrel member 14, which posts 36 can provide means for spacing the major side surface of the 20 frame 12 and the nozzle 21 of the device lO from a horizontal surface on which the device lO is laid, and which posts 36 have sockets 37 adapted to receive end portions of a generally ~-shaped wire 31 (Figure 5) to further space the device lO away from such a surface should 25 that be desired.
The sleeve 20 is made of a stiff heat-resistive polymeric material (e.g., Teflon~) made by an extrusion process to provide a polished inner surface with micro-scopic longitudinally extending scratches that facilitates 30 movement of the thermoplastic material through the sleeve 20, particularly after molten thermoplastic has cooled in the sleeve 20 and is again heated by the device lO.
The sleeve 20 is coupled to the barrel member 14 by a metal barrier ring 38 (Figures 2 and 3) that is heated 35 by the means for heating the barrel member 14, which barrier ring 38 provides means for restricting the extrusion of molten thermoplastic material between the 7~

block 2~ and the inner surface of the sleeve 20. The inlet barrier ring 38 is a generally cylindrical member having axially spaced radically outwardly projecting ribs 39 at one end positioned in a cylindrical socket in the end of the barrel member 14, between which ribs 39 is a sealing strip 40 pressed between the barrier ring 38 and barrel member 14 to provide a seal therebetween. An end portion 41 of the barrier ring 38 opposite the barrel member 14 is press fit into an internally relieved area of the sleeve 20. The barrier ring 38 has a cylindrical inside surface that is smaller in diameter than the inside diameter of the sleeve 20 (which sleeve 20 is adapted to always receive a block 24 with a slight clearance fit even when the diameter of the block 24 is at the upper end of its tolerance limits) so that the barrier ring 38 will receive a block 24 having a diameter at the upper end of its tolerance limits with a slight interference fit (e.g., an interference of up to 0.025 cm) or will receive a block 24 having a diameter at the lower end of its tolerance range with a clearance fit of about 0.050 cm. Surprisingly those blocks 24 with a diameter that provides such a slight interference fit with the barrier ring 38 will be melted sufficiently around their periphery by the heated barrier ring 38 that they can be easily pressed into the melting chamber 16, and blocks 24 of thermoplastic material with diameters that provide either such slight interference fits or clearance fits fit sufficiently close in the barrier ring 38 90 that no signifiant amount of molten polymeric material will extrude out of the melting chamber 16 between the block 24 and the barrier ring 38 and toward the outer end of the sleeve 20 between the block 24 and the sleeve 20.
The device 10 also includes three metal (preferably brass) cooling flangeq around the outer peri-phery of the sleeve 20 that provide means for developing predetermined temperature zones in the sleeve 20, including two closely spaced regulating flanges 45 at the end of the sleeve 20 adjacent the barrier ring 38 which cool and '7 regulate the temperature of the molten thermoplastic Material in the area between the barrier ring 38 and the sleeve 20, and a cooling flange 48 about centered along the length of the sleeve 20 that cools the sleeve 20 to restrict the thermoplastic material from becoming molten past that area along the sleeve 20, even if the heating means is activated for a long period of time during which molten thermoplastic material is not being dispensed from the device 10.
The barrel member 14 is of a suitable metal (e.g., aluminum). The melting chamber 16 in the barrel 14 is defined by a generally frustroconical inner surface tapered toward the valve assembly 18 to direct the molten polymeric material to the discharge passageway 17 through the valve assembly 18, and four equally spaced radially inwardly projecting ribs 42 which provide heated contact surfaces in addition to the frustroconical inner surface for engaging and melting the blocks 24 of thermoplastic material as they are pressed into the chamber 16. An electric heating element 43 which heats both the barrel member 14 and the barrier ring 38 is positioned in a socket 44 in the barrel member 14 beneath the chamber 16, and a thermostat 46 is fixed in a channel below the heating element 43 to disconnect electrical power normally supplied the heating element 43 via a power cord 47 and the thermostat 46 when the temperature of the barrel member 14 at the thermostat 46 exceeds a predetermined maximum (e.g.
200C).
The valve assembly 18 between the barrel member 14 and the nozzle 21 provides valve means for restricting molten thermoplastic material from running out of the nozzle 21 until a predetermined amount of force (e.g., about 0.9 to 1.8 kilograms) is manually applied to the block 24 of thermostatic material to cause pressure in the molten thermoplastic material in the melting chamber 16.
The valve assembly 18 is of the poppet valve type and includes a valve body 49 secured between the barrel member 14 and nozzle 21, which val~e body 49 defines the discharge passagewa~ 17 communicating between the Melting chamber 16 and the opening 19 through the nozzle 21. The discharge passageway 17 through the valve body 49 is normally closed by a head 50 on a valve normally biased against a valve seat on the end of the valve body 49 adjacent the nozzle 21 by a spring 52 compressed between a flange on the valve body 49 and a perforated retaining disk 54 fixed on a stem 53 of the valve, which disk 54 is axially slidably mounted in the valve body 49. Pressure from molten thermoplastic material in the melting chamber 16 and discharge passageway 17 caused by pressure manually applied to the block 24 of thermoplastic material can move the valve head 50 away from its seat against the bias of the spring 52 and allow molten thermoplastic material to pass the valve head 50 and be discharged through the nozzle 21. When the operator releases such pressure, however, the valve head 50 will aqain move to its seat under the influence of the spring 52 to prevent any more mol~en thermoplastic material within 23 the melting chamber 16 and discharge passageway 17 from escaping through the nozzle 21.
To use the dispensing device 10, an operator first connects the power cord 47 to a source of electrical power so that 'he barrel member 14 and barrier ring 38 are heated by the heating element 43. The operator then places the block 24 of thermoplastic material in the opening 22 through the sleeve 20, grabs the handles 26 with one hand, and uses the thumb of that hand to press against the pressure plate 32 to slide it along the track 34 into engagement with the block 24 and thereby press the block 24 through the sleeve 20 and barrier ring 38 and into the melting chamber 16 in the barrel member 14 where the end portion of the block 24 will be made molten by contact with the inner surface of the barrel member 14, including the inwardly projecting ribs 42. While the inner surface of the sleeve 20 will provide a clearance fit with the periphery of the block 24, even if the diameter of the block 24 is at 7~
-14~

the upper limit of its tolerance range, the barrier ring 38 has a cylindrical inner surface with a slightly smaller inner diameter than the inner diameter of the sleeve 20 and will provide a slight interference fit or a very close clearance fit with the block 24, depending on whether the diameter of the block 24 is at the upper or lower limit of its tolerance range~ If there is an interference fit, the barrier ring 38 will melt the periphery of the thermo-plastic block 24 sufficiently to allow it to easily pass;
and in either event the barrier ring 38 will greatly restrict extrusion of thermoplastic material from the melting chamber 16 back between the block 24 and the barrier ring 38 and thus between the block 24 and the inner surface of the sleeve 20. Sufficient pressure in the molten thermoplastic within the melting chamber 16 caused by manual pressure on the pressure plate 32 and block 24 will cause the head 50 of the valve to move away from its valve seat against the bias of the spring 52 so that the molten thermoplastic can flow around the head 50 and out the outlet opening 19 of the nozzle 21. When manual pressure is released on the pressure plate 32, the head 50 will again move to its seat under the influence of the spring 52 which stops the flow of molten material through the nozzle 21 and restricts air from reaching the molten thermoplastic material in the melting chamber 16, thereby restricting oxidation of the molten thermoplastic in the valve assembly 18. If the heating element 43 remains activated for a long time while no molten thermoplastic material is dispensed through the nozzle 21, heat buildup can cause the block 24 to melt (at least around its periphery), to about the midpoint of the sleeve 20 where such melting will be restricted by the cooling effect of the cooling flange 48. If the power is then discGnnected so that this molten thermoplastic material cools and solidifies, and the power is then again connected to heat the heating element 43, the thermoplastic material in the valve assembly 18 will be some of the first thermoplastic '7~

material melted and the valve assembly 18 can act as a relief valve for pressure developed in the barrel member 14 as the rest of the thermoplastic material in the barrel member 14 melts. Also, the smooth longitudinally 5 microgrooved inner surface of the sleeve 20 will facilitate breaking loose of the block 24 from the sleeve 20 to press i~ through the barrier ring 38 and into the melting chamber 16 to again cause the molten thermoplastic material to flow out of the nozzle 21.
When the outer end of the block 24 of thermo-plastic material reaches the outer end of the sleeve 20, the operator can manually retract the pressure plate 32 along its track 34 via one of the wing portions 35 and press a new block 24 of thermoplastic material transversely 15 between the gripping parts 30 of the holding bracket 28, whereupon the new block 24 will be held in proper alignment with the sleeve 20, and the operator can again use the pressure plate 32 to press the new block 24 into the melting chamber 16.
Referring now to Figures 7 through 10 of the drawing there is shown a dispensing device 60 for molten thermoplastic material according to the present invention, which device 60 has the same structure as the device lQ
except that the channel 29 and pressure plate 32 of the 25 device 10 have been replaced by a manually operated feeding assembly 62, which assembly 62 is adapted a feed a block 64 of solid thermoplastic material having the shape best illustrated in Figure 6. Parts of the device 60 that have the same structures as parts-of the device 10 have been 30 given the same reference numerals to which have been added the suffix "a".
The block 64 of solid thermoplastic material (Figure 6) comprises a plurality of coaxial generally cylindrical portions 66 with uniform predetermined axial 35 and diametrical dimensions (e.g., about 0.38 centimeter and 1.5 centimeter respectively), which generally cylindrical portions 66 are uniformly axially spaced along the block 64 by similarly sized and oriented portions 68 having rectan-gular cross sections (preferably square as illustrated) having uniform diagonal dimensions about equal to the diametrical dimensions of the cylindrical portions 66, having corners aligned with ~he peripheries of the cylindrical portion 66 and having axial dimensions that are substantially less than those of the cylindrical portion 66 (e.g., about 0.25 centimeter). These alternating cylindrical and rectangular portions 66 and 68 result in a block 64 with evenly spaced projecting arcuate parts of the cylindrical portions 66 projecting from each of four sides of the block 64 defined by the aligned peripheral surfaces of the rectangular portions 68. These projecting arcuate parts provide uniformly spaced opposed arcuate teeth along opposite sides of the block 64 with planar slug surface portion between roots of adjacent teeth, and these teeth or projecting parts of the cylindrical portion 66 are like teeth on a rack and allow the block 64 to be aligned and driven by the feeding assembly 62, as will be further explained below. The spaces between these projecting parts of the cylindrical portions 66 also provide receptacles for molten material to facilitate melting the block 64 within the device 60 as has previously been described.
Like the dispensing device 10, the device 60 comprises a tw~ part frame 12a, a barrel member 14a mounted between the parts of the frame 12a and having an internal melting chamber communicating via a discharge passageway through a valve assembly 18a with an outlet opening through a nozzle 21a, and a sleeve 20a with a cylindrical through opening having one end secured to the barrel member 14a with its through opening communicating with the end of the melting chamber opposite the discharge passageway. The sleeve 20a is adapted to receive the block 64 of solid thermoplastic material within the cylindrical through opening with a slight clearance fit even when the diameter of the block 64 is at the large end of its tolerance range, with one end portion of the block 64 in the melting chamber 7~

and the block 64 projecting through the opening in the sleeve 20a. Means are provided in the device 60 for heating the barrel member to melt the end portion of the block 64 therein. The frame 12a includes a handle 26a positioned so S that an operator can grip the handle 26a with the fingers of one hand while applying pressure with the thumb of that hand to press the block 64 through the sleeve 20a and into the melting chamber to force molten thermoplastic material out of the melting chamber through the valve assembly 18a and nozzle 21a.
Unlike the device 10, the device 60 includes the feeding assembly 62 at the end of the sleeve 20a opposite the barrel member 14a, which feeding assembly 62 includes means adapted for receiving and for holding the block 64 of solid thermoplastic material in the sleeve 20a, while affording the application of force by the thumb of an operator on the block 64 to press it into the sleeve 20a toward the melting chamber.
As illustrated, the feeding assembly 62 comprises ~1) wall means or walls 74 removably fixed to the frame 12a, that define a passageway 76 adapted to guide the solid thermoplastic material block 64 in alignlDent with the through opening in the sleeve 20a: (2) a slide 78 having a cylindrically concave upper surface 80 adapted to support the block 64, having projecting parts defining a recess 82 opening through its side opposite its upper surface 80 adapted to receive the end portion of an operator's thumb 83, and being mounted on the walls 74 for movement along a path generally aligned with the melting chamber from a retracted position spaced from the sleeve 20a to an advanced position more closely adjacent the sleeve 20a and back to its retracted position, the recess 82 being accessible by the thumb 83 of an operator gripping the handle 26a to afford manual reciprocation of the slide 78 between its retracted and advanced positions by the operator; (3) drive means comprising a drive member 84 pivotably mounted on the slide 78 adapted for engaging the cylindrical portions 66 of the block 64 of thermoplastic material and advancing the block 64 toward the melting chamber durin~ movement of the slide 78 from its retracted to its advanced position, and for moving around the cylindrical portions 66 and along the block 64 of thermoplastic during movement of the slide 78 from its advanced to its retracted position; and (4) means comprising a sprocket wheel 86 rotatably mounted on the walls 74 for aligning the block 64 of thermoplastic in the passageway 76 for engagement by the drive member 84 and for providing friction to help retain the block 64 in the passageway 76 before it is engaged by the drive means.
The walls 74 that define the passageway 76 for receiving the block 64 in a position aligned with the through opening in the sleeve 20a each have generally arcuate opposed portions 88 (Figure 8) relieved along their inner surfaces to receive the gripping parts 30a and the surrounding supporting structure of the frame 12a, and having through slots 90 (Figure 7) at their ends adjacent the sleeve 20a that receive normally horizontal reinforcing webs on the frame 12a. The walls also include transverse end wall portions 92 (Figure 7) at their ends opposite the sleeve 20a that interlock at their bottom edge, and longitudinally extending opposed contacting top wall portions 94 that are held together by a U-shaped spring metal channel 96 that fits around the top wall 94 portions to hold the walls 74 in place around the gripping parts 30a and adjacent portions of the frame 12a. The arcuate portions 88 of the walls 74 have inner surfaces that, with the inner surfaces of the gripping parts 30a, define the passageway 76 that has an inlet through the end wall portions 92.
The walls 74 also include opposed longitudinally extending spaced ledges 98 along their edges opposite the top wall portions 94, and the slide 78 has opposite longitudinally extending grooves to receive the ledges 98 to afford reciprocation of the slide 78 along the ledges 98 between its retracted and advanced positions.
The drive member 84 is elongate, has a pluralit~
of or three teeth 102 adapted to engage between the cylindrical portions 66 of the block G4 projecting from one side adjacent a first end and is positioned in a groove in the slide 78 extending axially of the passageway 76 with its longitudinal direction generally parallel to the passageway 76 and the teeth 102 adjacent the sleeve 20a.
The drive member 84 has its second end opposite its first end mounted on the slide 78 by a pivot pin 100 extending transverse to the passageway 76 for pivotal movement between (1) an engage position (Figure 9) with the teeth 102 in engagement between the cylindrical portions 66 of a block 64 positioned in the passageway 76 ~to which engage position the drive member 84 is biased by a coil spring 104 between projections 106 and 107 projecting respectively from the sides of the drive member 84 and slide 78 opposite the passageway 76): and (2) a release position (Figure 10) with the teeth 102 spaced from the block 64 in the passageway 76 (toward which release position the drive member 84 can be pivoted by camming movement of the inclined rear surface of the teeth 102 over the cylindrical portions 66 of the block 64 and/or engagement of an operator's thumb with the projection 106 to move the slide 78 toward its retracted position~.
Additionally means are provided for restricting pivotal movement of the drive member 84 from its engage to its release position when an operator applies force to the slide 78 to move it towards its advanced position. The opening through the drive member 84 in which the pivot pin 100 is received is elongate in a direction parallel to the passageway 76 so that, in its engage position, the drive member 84 can move axially of the passageway 76 and longitudinally with respect to the slide 78 on which it is mounted between (1) a normal position to which it is biased by the spring 104 and from which it can be pivoted to its release position due to separation between a lock pin 108 through the drive member 84 and the slide 78 (Figure 10), -20~

and (2) a locked position (Figure 9) with the lock pin 108 engaged in a transverse groove along a forward facing surface on the slide 78, to which locked position the drive member 84 will be moved ayainst the bias of the spring 10 by a ~orce transfe~red from the slide 78 to ~he drive member 84 to press the block 64 into the sleeve 20a.
The sprocket wheel 86, which provides means for aligning the block 64 of thermoplastic in the passageway 76 for engagement by the teeth of the drive member 84 and for providing sufficient friction to retain the block 64 in the passageway 76 before it is engaged by the drive member 84, is rotatably mounted on a pin 110 extending transverse of the passageway 76 on the side o~ the passageway opposite the drive member 84 and adjacent the inlet of the passageway 76. The sprocket has a plurality of teeth with axially extending parallel tips spaced to engage betwen the projecting parts of the cylindrical portions 66 and engage the corresponding planar surfaces of the rectangular - portions 68 therebetween to orient those contacted planar surfaces parallel to the teeth and axis of the sprocket 86, and to thereby orient the opposite corresponding planar surfaces of the rectangular portions 68 parallel to the - teeth 102 on the drive member 84.
To use the dispensing device 60, an operator first connects its power cord 47a to a source of electrical power so that its barrel member 14a and barrier ring are heated by its heating element. After insuring the slide 78 is in its retracted position, the operator inserts one end of the block 64 of thermoplastic material into the open inlet end of the feeding assembly 62 which orients the block 64 in the passageway 76 by engagement of the teeth on the sprocket wheel 86 along corresponding sides of its rectangular portions 68. He then grabs the handle 26a with one hand, engages the thumb of that hand in the recess 82 in the slide 78 and uses his thumb to move the slide 78 so that the teeth 102 on the drive assembly engage between the cylindrical portions 66 on the block 64 to press the block '7t~

64 toward the sleeve 20a and into the melting chamber in the barrel member 14a where the end portion of the block 64 will be made molten by contact with the inner surface cf the barrel ~ember 14a. As the slide 78 is thus moved from its retracted position toward its advanced position, the force applied through the drive member 84 will allow the drive member 84 to slide longitudinally against the bias of the spring 104, causing the lock pin 108 to engage the transverse slot in the leading surface of the slide 78 and 1 thereby preventing the drive member 84 from moving toward its release position.
After the slide 78 is thus moved fully to its advance position, the operator can manually retract the slide 78 along the periphery of the block 64 by engagement of his thumb against the projection 106 on the drive member 84 which projects into the recess 82 in the slide 78, which engagement will cause the drive member 84 to move relative to the slide 78, the lock pin 108 to move out of the groove in the slide 78, and the drive member 84 to pivot so that the teeth 102 move out of engagement with and along the periphery of the block 64 in the passageway 76: whereupon the operator can again manipulate the slide 78 with his thumb to engage the teeth 102 with a new portion of the block 64 and continue pressing it into the sleeve 20a and the melting chamber. Preferably the teeth 102 have leading edges that are disposed at about 89 degrees with respect to the longitudinal direction of the drive member 84 to help the teeth 102 release from the block 64.
Referring now to Figures 11 through 16 there is illustrated a method and device 120 according to the present invention for making the block 64 of thermoplastic material shown in Figure 6.
As illustrated, the device 120 comprises first and second chain-like structures 122 and 123, each comprising a plurality of block shaped molds 124. Each of the molds 124 ~Figures 15 and 16) has parallel end surfaces 125, a side surface or face 126 disposed at a right angle with respect to its end surfaces 125, and an elongate centrally located cavity 128 opening through its face 126 and end surfaces 125. The cavity 128 has the shape of one half of the block 64 divided along a plane through its axis and two opposite corners of each of its rectangular portions 68. The molds 124 in the first chain like structure 122 are attached together close to their end surfaces 125 by flanking circular pivot plates 130 pivotably connected to the molds 124 by shoulder bolts 131;
and the molds 124 in the second chain like structure 123 are attached together close to their end surfaces 125 by flanking semicircular pivot plates 132 pivotably connected to the molds 124 by shoulder bolts 133. The pivot plates 132 have semicircular recesses 134 in their sides adjacent the faces 126 of the molds 124 which vill receive portions of the circular pivot plates 130 and allow adjacent molds 124 between the chain like structures 122 and 123 to be longitudinally registered in face 126 to face 126 contact with the mold cavities 128 aligned between the faces 126 of : 20 the molds 124 and with the end surfaces 125 of adjacent molds 124 along each of the chain like structures 122 and 123 in contact with the ends of the cavities 125 opening through the end surfaces 125 aligned between adjacent molds 124.
The two chain like structures 122 and 123 are disposed around and extend between pairs of sprockets 135, 136 and 137, 138 respectively each rotatable about a vertical axis, with each pair of sprockets 135, 136 and 137, 138 spaced and posi~ioned to allow adjacent lengths of 30 the chain like structures 122 and 123 to move along a linear path portion 139 vith the molds 124 in face 126 to face 126 contact and slideably supported along their lower surface by a support 148 (Figure 14). Along that linear path portion 139 the molds 124 will be maintained in face 35 126 to face 126 contact by two rows of rollers 140 that are spaced to engage the surfaces of the molds 124 opposite their faces 126. The sprockets 135, 136, 137, and 138 have semicircular notches 141 shaped to closely receive circular portions of the pivot plates 130 or 132 to ~oth help keep the chain like structures 122 and 123 in synchronism, and to drive the chain like structures 122 and 123 via a roller chain 142, sprockets 143, 144, 145 and 146 and a gear reduced variable speed drive unit 147 as is shown in Figure 11. The sprockets 135 and 137 are spaced apart and spaced from the inlet end of the linear path portion 139 defined by the rollers 140 (Figure 1~) so that the faces 126 of the molds 124 are spaced apart at the nip of the sprockets 135 and 137 (e.g., about 2.5 centimeter) and the molds 124 move along generally parallel but converging path portions for a short distance (e.g., about 18 centimeters) between the peripheries of the sprockets 135 and 137 and the linear path portion 139; and the sprockets 136 and 138 are spaced apart and spaced from the outlet end of the linear path portion 139 so that the molds 124 move along a generally parallel but diverging path portion for a short distance (e.g., about 30 centimeters) from that outlet to the peripheries of the sprockets 136 and 138 (Figure 13) where the faces 126 of the molds 124 are spaced apart (e.g., 3.8 centimeter). This allows the pivot plates 130 and 132 to move in proper alignment for engagement or disengagement of the circular plates 130 with the recesses 134 in the plates 132 in directions generally normal to the faces 126 of the molds 124 before or after the plates 130 and 132 engage along the linear path portion 139 as a result of contact by the rollers 140, which engagement or disengagement could not so easily occur if the blocks moved into and out of face 126 to face 126 contact at the peripheries of the sprockets 135, 137; 136, 138; and allows the molds 124 to separate sufficiently in a direction generally normal to the faces 126 to disengage the projecting parts of the cylindrical portions 66 of the newly formed block 64 of adhesive from the cavities 128 in the molds 124 before the molds 124 start to move away from each other around the sprockets 136 and 138.

Molten polymeric material is delivered through an elongate tu~e 150 from a so~rce such as an extruder (not shown) into the cavity between the face 126 to face 126 molds 124 alony the linear path portion 139, which tube 150 has a square periphery sized and oriented to just fit inside the cavity between the parts of the molds 124 that form the portions 68 with square cross square cross sections for the block 64 of thermoplastic material 64 (Figure 14). The molten material cools and solidifies as the molds 124 move along the linear path portion 139, and the continuously molded block 64 of thermoplastic material is expelled from between the ~olds 124 as they separate and can be propelled through a guide tube 153 into a device 160 shown in Figures 17, 18 and 19 for cutting the continuously molded block 64 of adhesive into predetermined lengths.
Referring now to Figures 17 through 19 there is illustrated a method and the device 160 according to the present invention for cutting the cont'inuously molded block 64 of thermoplastic materials made by the device 120 into predetermined lengths.
As illustrated, the device 160 comprises first and second chain-like structures 162 and 163, each comprising a plurality of block shaped support members 164. Each of the support members 164 has end surfaces 165, a side surface or face 166 between its end surfaces 165, and an elongate centrally located semicylindrical recess 167 opening through its face 166 and end surfaces 165 adapted to receive one half of the block 64. The support members 164 in the first chain like structure 162 are attached together adjacent their end surfaces 165 by flanking circular pivot plates 170 pivotably connected to the support members 164 by shoulder bolts 171, and the support members 164 in the second chain like structure 163, are attached together adjacent their end surfaces 165 by flanking semicircular pivot plates 172 pivotably connected to the support members 164 by shoulder bolts 173. The pivot plates 172 have semicircular recesses 174 in their sides adjacent the faces '7~

166 of the support members 164 which will receive portions of the circular pivot plates 170 and allow adjacent support members 164 between the chain like structures 162 and 163 to be longitudinally registered in faces 166 to face 166 contact with the recesses 167 aligned between the support members 164.
The two chain like structures 162 and 163 are disposed around and extend between pairs of sprockets 175, 176 and 177, 178 respectively, with each pair of sprockets 10 175, 176, and 177, 178 spaced and positioned to allow adjacent lengths of the chain like structures 162 and 163 between the pairs of sprockets 175, 176 and 177, 178 to move in face 166 to face 166 contact. The sprockets 175, 176, 177, and 178 have semicircular notches 180 shaped to closely receive circular portions of the pivot plates 170 or 172 to both help keep the chain like structures 162 and 163 in synchronism, and to drive the chain like structures 162 and 163 90 that rotation of two of the sprockets 175, 177 or 176, 178 by a drive connection (not shown) powered by the drive unit 147 can drive the chain like structures 162 and 163 in synchronism with the chain like structures 122 and 123 of the device 120. Thus the pair of sprockets 175, 176 and 177, 178 provide means for moving each of the chain like structures 162 and 163 around a separate path with portions of the chain like structures 162 and 163 moving in face 166 to face 166 relationship along a linear cut off path portion from a beginning of the cut off path portion between the sprockets 175 and 177 positioned to receive the block 64 from the device 120 to an end of the linear cut off path portion between the sprockets 176 and 178 where severed pieces of the block 64 are expelled.
A plurality of knives 182 are mounted on the support members 164 of the first chain like member 162 between edge guides 183 fixed to those support members for movement in a direction transverse to the recess 174 . between a retracted position spaced from the recess 174 and 7~

a severed portion extending across the recess 174 in support members 164 along the cut off path portion.
Means are provided for moving the knives 182 from their retracted positions to their engaged positions along the cut off path portion to cut the block 64 into predetermined lengths, and for returning the knives 182 to their retracted positions along a portion of the path spaced from said cut off path portion. The support members 164 on the second chain like structure 163 are supported on their sides opposite their recess 174 by a plurality o~
rollers 185 rotatably mounted on a frame members 186. A
circular cam 188 is mounted for rotation about an axis parallel to and spacéd from its axis and is driven by means (not shown) in an eccentric path so that it will engage and press each knife 182 from its retracted to its engaged position as the knife 182 moves past the cam 188 along the cut off portion of the path. Such movement will sever the block 64 which will be expelled from between the chain like structures 162 and 163 as they separate around the 20 sprockets 176 and 178, and movement of the support members 164 carrying the knives 182 around the sprocket 176 will cause the knives 182 to return to their retracted positions under the influence of gravity as those support mem~ers 164 move along the portion of the path for the first chain like structure 162 spaced from the cut off path portion. Knives 182 may be removed from certain of the support members 164 as desired to provide blocks 64 of different predetermined lengths.
The present inventions have now been described with reference to single embodiments thereof. It will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the scope of the present inventions. Thus the scope of the present invention should not be limited to the structures described in this application, but only by structures described by the language of the claim and their equivalents. For example, with some loss of flexibility a '7~

thermoplastic block useable in the device could have uniformly spaced opposed arcuate rock like teeth along only two opposite sides, with parallel planar slug surfaces between the roots of adjacent teeth.

Claims (13)

1. In combination, a block of solid thermoplastic material comprising coaxial generally cylindrical portions of uniform predetermined, axial and diametrical dimensions uniformly axially spaced along the block by rectangular portions having diagonal dimensions about equal to said diametrical dimension; and a device for dispensing molten thermoplastic material from said block comprising a frame including a handle positioned so that an operator can grip the handle with the fingers of one hand, a barrel member mounted on said frame and having an internal melting chamber communicating with an outlet opening through a nozzle, a sleeve with a through opening having one end secured to said barrel member with said through opening communicating with the end of said melting chamber opposite said outlet opening, said sleeve being adapted to received said block of solid thermoplastic material with one end portion of the block in the melting chamber and the block projecting through said sleeve, means for heating said barrel member to melt the end portion of the block therein, and a feeding mechanism at the end of said sleeve opposite said melting chamber comprising wall means fixed to said frame and defining a passageway adapted to guide the solid thermoplastic material block in alignment with the through opening in said sleeve, a slide having an upper surface positioned adjacent one side of the block, and being mounted on said frame for movement along a path generally aligned with the melting chamber from a retracted position spaced from said sleeve to an advanced position more closely adjacent the sleeve and back to said retracted position, drive means carried by said slide adapted for engaging said cylindrical portions and advancing the block of thermoplastic material toward the melting chamber during movement of said slide from its retracted to its advanced position, and for moving around the cylindrical portions and along the block of thermoplastic during movement of said slide from its advanced to its retracted position, means for aligning the block of thermoplastic in said passageway for engagement by said drive means, and means projecting from the side of said slide opposite said upper surface in a direction generally at a right angle to said upper surface including a first projecting part adjacent said sleeve and a second projecting part spaced from the side of said first projecting part opposite said sleeve for defining a recess between said first and second parts adapted to receive the end portion of the thumb of an operator gripping said handle to afford manual movement of said slide body toward said advanced position and toward said retracted position.

2. A combination according to claim 1 wherein said rectangular portions are square in cross section.

3. A combination according to claim 1 wherein said means for aligning comprises a sprocket having teeth spaced to engage between said cylindrical portions along corresponding sides of said rectangular portions, said sprocket being mounted on sand wall means on the side of said passageway opposite said drive means for rotation about an axis disposed transverse of said passageway.

4. A combination according to claim 1 wherein said drive means comprises an elongate drive member having a plurality of teeth adapted to engage between the cylindrical portions of the block, said teeth projecting from one side of said drive member adjacent a first end of said drive member, said drive member being oriented on said slide with its longitudinal direction generally parallel to said passageway and said teeth adjacent said sleeve and having a second end opposite said first end mounted on said slide both for pivotal movement of said drive member relative to said slide between an engage position with said teeth in engagement between cylindrical portions of said block in said passageway and a release position with the teeth spaced from the block in the passageway, and for longitudinal movement relative to said slide between a normal position and a locked position with said teeth farther from said sleeve with respect to the same position of said slide when said drive member is in said normal position; means adapted for engagement between said slide and said drive member to prevent pivotal movement of said drive member away from said engage position when said drive member is in said locked position and to afford movement of said drive member from said engage position to said release position when said drive member is in said normal position, and a spring between said slide and said drive member for biasing said drive member to said normal and engage positions, said drive member is in said normal position, and a spring between said slide and said drive member for biasing said drive member to said normal and engage positions, said drive member having a projection projecting into said recess and manually engageable to pivot said drive member to said release position when said slide is manually moved toward said retracted position.

5. A combination according to claim 4 wherein said teeth have cam surfaces on their sides opposite said sleeve adapted to cam said teeth around said cylindrical portions of said block by pivoting said drive member toward said release position when said slide is manually moved from said advanced position toward said retracted position.

6. A device adapted for dispensing molten, thermoplastic material from a block of the solid thermoplastic material comprising coaxial generally cylindrical portions of uniform predetermined axial and diametrical dimensions uniformly axially spaced along the block by rectangular portions having diagonal dimensions about equal to said diametrical dimension, said device comprising a frame including a handle positioned so that an operator can grip the handle with the fingers of one hand;
a barrel member mounted on said frame and having an internal melting chamber communicating with an outlet opening through a nozzle; a sleeve with a through opening having one end secured to said barrel member with said through opening communicating with the end of said melting chamber opposite said outlet opening, said sleeve being adapted to receive a said block of solid thermoplastic material with one end portion of the block in the melting chamber and the block projecting through said sleeve; means for heating said barrel member to melt the end portion of the block therein; and a feeding mechanism at the end of said sleeve opposite said melting chamber comprising wall means fixed to said frame and defining a passageway adapted to guide the solid thermoplastic material block in alignment with the through opening in said sleeve, a slide having an upper surface positioned adjacent said passageway, and being mounted on said frame for movement along a path generally aligned with the melting chamber from a retracted position spaced from said sleeve to an advanced position more closely adjacent the sleeve and back to said retracted position, drive means carried by said slide adapted for engaging said cylindrical portions and advancing the block of thermoplastic material toward the melting chamber during movement of said slide from its retracted to its advanced position, and for moving around the cylindrical portions and along the block of thermoplastic during movement of said slide from its advanced to its retracted position, means for aligning the block of thermoplastic in said passageway for engagement by said drive means, and means projecting from the side of said slide opposite said upper surface in a direction generally at a right angle to said upper surface including a first projecting part adjacent said sleeve and a second projecting part spaced from the side of said first projecting part opposite said sleeve for defining a recess between said first and second parts adapted to receive the end portion of the thumb of an operator gripping said handle to afford manual movement of said slide both toward said advanced position and toward said retracted position.

7. A device according to claim 6 wherein said means for aligning comprises a sprocket having teeth spaced to engage between said cylindrical portions along corresponding sides of said rectangular portions, said sprocket being mounted on said wall means on the side of said passageway opposite said drive means for rotation about an axis disposed transverse of said passageway.

8. A device according to claim 6 wherein said drive means comprises an elongate drive member having a plurality of teeth adapted to engage between the cylindrical portions of the block, said teeth projecting from one side of said drive member adjacent a first end of said drive member, said drive member being oriented on said slide with its longitudinal direction generally parallel to said passageway and said teeth adjacent said sleeve and having a second end opposite said first end mounted on said slide both for pivotal movement of said drive member relative to said slide between an engage position with said teeth in engagement between cylindrical portions of a said block in said passageway and a release position with the teeth spaced from the block in the passageway, and for longitudinal movement relative to said slide between a normal position and a locked position with said teeth farther from said sleeve with respect to the same position ox said slide when said drive member is in said normal position, means adapted for engagement between said slide and said drive member to prevent pivotal movement of said drive member away from said engage position when said drive member is in said locked position and to afford movement of said drive member from said engage position to said release position when said drive member is in said normal position, and a spring between said slide and said drive member for biasing said drive member to said normal and engage positions, said drive member having a projection projecting into said recess and manually engageable to pivot said drive member to said release position when said slide is manually moved toward said retracted position.

9. A device according to claim 8 wherein said teeth have cam surfaces on their sides opposite said sleeve adapted to cam said teeth around the cylindrical portions of a said block by pivoting said drive member toward said release position when said slide is manually moved from said advanced position toward said retracted position.

10. A feeding mechanism adapted for use on a device for dispensing molten, thermoplastic material from a block of the solid thermoplastic material comprising coaxial generally cylindrical portions of uniform predetermined axial and diametrical dimensions uniformly axially spaced along the block by rectangular portions having diagonal dimensions about equal to said diametrical dimension, said device comprising a frame including a handle positioned so that an operator can grip the handle with the fingers of one hand; a barrel member mounted on said frame and having an internal melting chamber communicating with an outlet opening through a nozzle, a sleeve with a through opening having one end secured to said barrel member with said through opening communicating with the end of said melting chamber opposite said outlet opening, said sleeve being adapted to receive the block of solid thermoplastic material with one end portion of the block in the melting chamber and the block projecting through said sleeve; and means for heating said barrel member to melt the end portion of the block therein; said feeding mechanism comprising wall means adapted to be attached to said frame at the end of said sleeve opposite said melting chamber and defining a passageway adapted to guide the solid thermoplastic material block in alignment with the through opening in said sleeve; a slide having an upper surface adapted to support the block and being mounted on said frame for movement along a path generally aligned with the melting chamber from a retracted position spaced from said sleeve to an advanced position more closely adjacent the sleeve and back to said retracted position; drive means carried by said slide adapted for engaging said cylindrical portions and advancing the block of thermoplastic material toward the melting chamber during movement of said slide from its retracted to its advanced position, and for moving around the cylindrical portion and along the block of thermoplastic during movement of said slide from its advanced to its retracted position; means for aligning the block of thermoplastic in said passageway for engagement by said drive means; and means projecting from the side of said slide opposite said upper surface in a direction generally at a right angle to said upper surface including a first projecting part adjacent said sleeve and a second projecting part spaced from the side of said first projecting part opposite said sleeve for defining a recess between said first and second parts adapted to receive the end portion of the thumb of an operator gripping said handle to afford manual movement of said slide both toward said advance position and toward said retracted position.

11. A feeding mechanism according to claim 10 wherein said means for aligning comprises a sprocket having teeth spaced to engage between said cylindrical portions along corresponding sides of said rectangular portions, said sprocket being mounted on said wall means on the side of said passageway opposite said drive means for rotation about an axis disposed transverse of said passageway.

12. A feed mechanism according to claim 10 wherein said drive means comprises an elongate drive member having a plurality of teeth adapted to engage between the cylindrical portions of the block, said teeth projecting from one side of said drive member adjacent a first end of said drive member, said drive member being oriented on said slide with its longitudinal direction generally parallel to said passageway and said teeth adjacent a said sleeve and having a second end opposite said first end mounted on said slide both for pivotal movement of said drive member relative to said slide between an engage position with said teeth in engagement between cylindrical portions of a said block in said passageway and a release position with the teeth spaced from the block in the passageway, and for longitudinal movement relative to said slide between a normal position and a locked position with said teeth farther from the sleeve with respect to the same position of said slide when said drive member is in said normal position; means adapted for engagement between said slide and said drive member to prevent pivotal movement of said drive member away from said engage position when said drive member is in said locked position and to afford movement of said drive member from said engage position to said release position when said drive member is in said normal position, and a spring between said slide and said drive member for biasing said drive member to said engage and normal positions, said drive member having a projection projecting into said recess and manually engageable to pivot said drive member to said release position when said slide is manually moved toward said retracted position.

13. A feed mechanism according to claim 12 wherein said teeth have cam surfaces on their sides opposite the sleeve adapted to cam said teeth around the cylindrical portions of a said block by pivoting said drive member toward said release position when said slide is manually moved from said advanced position toward said retracted position.