WO2012036730A1

WO2012036730A1 - Internally mixed front head

Info

Publication number: WO2012036730A1
Application number: PCT/US2011/001575
Authority: WO
Inventors: Richard D. Anderson; Steven R. Sinders; Jonathan R. Mc Michael
Original assignee: Graco Minnesota Inc.
Priority date: 2010-09-13
Filing date: 2011-09-13
Publication date: 2012-03-22
Also published as: WO2012036730A4; TW201221227A; WO2012036730A9

Abstract

A front head assembly for a plural component dispensing gun includes a front head body, a static mixer, and an integrator pin. The front head body has a plurality of ports at a rear end and a head cavity extending into a front end of the front head body. The static mixer is positioned in the head cavity between the plurality of ports and the front end of the front head body. The integrator pin is positioned in the interior of the front head body between the plurality of ports and the static mixer.

Description

I NTERNALLY MIXED FRONT H EAD

BACKGROUND

The present invention relates to plural component dispensing devices and, more particularly, to an integrator pin in an internal m ix front head assembly of a plural component dispensing gun.

I n an internal mi x plural component d ispensing gun, a resin and a catalyst are independently routed to a front head assembly. I n the front head assembly, the resin and the catalyst are mixed in a static mixer prior to ex iti ng the dispensing gun. Because the resin and the catalyst are substantially di fferent l iquids (e.g. they have sign i ficantly dissimi lar viscosities), the static mixer must have many stages in order to make the materia ls mix. This makes the length o f the front head assembly quite long and ungainly. In addition, after the user ceases dispensing from the gun, the resin/catalyst mixture in the front head assembly has residual pressure that will continue to force materia l out of the front head assembly against the wishes of the user. Furthermore, because the resin and catalyst begin reacting a nd hardening as soon as they are mixed, the front head assembly needs to be flushed and/or cleaned regularly after being used.

SUMMA RY

I n one embodiment to the present invention, a front head assembly for a plural component dispensing gun includes a front head body, a static mixer, and an integra tor pin. The front head body has a plura lity o f ports at a rear end and a head cavity extending into a front end of the front head body. The static mixer is positioned in the head cavi ty between the plurality of ports and the front end of the front head body. The integrator pin is positioned in the i nterior of the front head body between the plura lity of ports and the static m i xer.

I n another embodiment, a front head for a plura l component dispensing gun includes a front head body, a m ixi ng cavity, a resin port, a catalyst port, a resin tunnel , a cata lyst tunnel, and an integrator pin. The front head body has a rear end and a front end. The mixing cavity extends into the front end o f the front head body and has a mixing basin at a rear end of the mixing cavity and a mix ing tunnel extending to the front end of the front head body from the mixing basin. The resin port and catalyst port extend into the rear end of the front head body. The resin tunnel fluidly connects the resin port to the mixing cavity, and the catalyst tunnel fluidly connects the catalyst port to the mixing cavity. The integrator pin is attached to the front head body at the rear end of the mixing cavity. The integrator pin has a wall that extends into the mixing basin, wherein the integrator pin is positioned between the catalyst tunnel and the mixing runnel.

In another embodiment, an integrator pin for a plural component dispensing gun includes a cylindrical base that has a circular face and a cylindrical face. In addition, the integrator pin has a wall extending from the circular face with a projection of the wall extending substantially across an entire diameter of the circular face.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side perspective view of a dispensing gun with a front head assembly removed.

FIG.2 is a rear perspective view of the front head assembly showing a catalyst port, a resin port, and a retainer.

FIG.3 is a cross-section perspective view of the front head assembly showing an integrator pin and a check valve.

FIG.4 is a side perspective view of the integrator pin showing a cylindrical base and a wall.

DETAILED DESCRIPTION

In FIG. 1, a side perspective of dispensing gun 10 is shown with front head assembly 12 removed. Shown in FIG. 1 are dispensing gun 10, front head assembly 12, catalyst inlet 14A, resin inlet 14B, solvent inlet 14C, air inlet 14D, handle 16, trigger 18, valve controller 20, catalyst outlet 22, resin outlet 24, solvent outlet 26, air outlet 28, retainer 30, tip 32, air cap 34, cap ring 35, solvent valve 36, and external thread 37.

In the illustrated embodiment, dispensing gun 10 has catalyst inlet 14A, resin inlet 14B, solvent inlet 14C, and air inlet 14D at a rear end of dispensing gun 10. Projecting from the bottom of dispensing gun 10 is handle 16. Trigger 18 is positioned forward of handle 16, and is connected to valve controller 20. Catalyst outlet 22, resin outlet 24. solvent outlet 26, and air outlet 28 are positioned at a front end of dispensing gun 10 and are connected to front head assembly 12 when front head assembly 12 is attached to dispensing gun 10 (as is required for operation of dispensing gun 10). Outlets 22-28 allow flow out of the front of dispensing gun 10. Also at the front end of dispensing gun 10 is external thread 37. Front head assembly 12 has retainer 30 rotatably attached at the rear of front head assembly 12, and tip 32 and air cap 34 are attached at the front of front head assembly 12 by cap ring 35. Retainer 30 is configured to engage with external thread 37 in order to attach front head assembly 12 to dispensing gun 10.

When a user pulls trigger 18, valve controller 20 opens needle valves (not shown) inside dispensing gun 10. Because, the resin, the catalyst, and the air are pressurized, this allows for the components to travel through dispensing gun 10 and out of front head assembly 12. More specifically, the resin, the catalyst, and air travel from catalyst inlet 14/\. resin inlet 14B, and air inlet I4D, through catalyst outlet 22. resin outlet 24, and air outlet 28 respectively, and into front head assembly 12. The resin and the catalyst are mixed in front head assembly 12 and dispensed out of tip 32 as a mixture. The air is expelled out ol air cap 34 in order to shape the mixture being dispensed out of tip 32.

When the user releases trigger 18, valve controller 20 closes the needle valves (not shown), and the resin, the catalyst, and air cease (lowing through dispensing gun 10 and out of front head assembly 12. If necessary, the user can open solvent valve 36, which is attached to dispensing gun 10 immediately forward of and fluidly connected to solvent inlet 14C. This allows for pressurized solvent to flow through dispensing gun 10 and solvent outlet 26, into front head assembly 12. The solvent forces the mixture out of tip 32, flushing front head assembly 12.

The components and configuration of dispensing gun 10 as shown in FIG. 1 allow for the resin and the catalyst to be mixed and dispensed in a controlled manner. In addition, retainer 30 and external thread 37 allow for front head assembly 12 to be detached from dispensing gun 10 in order to clean and/or replace front head assembly 12.

In FIG. 2, a rear perspective of front head assembly 12 is shown, including catalyst port 40, resin port 42, and retainer 30. Shown in FIG.2 are front head assembly 12. retainer 30, front head body 38, catalyst port 40, resin port 42, solvent port 44, air port 46. gripping texture 48, and internal thread 50.

As stated previously, front head assembly 12 is detached from the rear end of front head assembly 12 by retainer 30. More specifically, retainer 30 is rotatably attached to front head body 38 of front head assembly 12. Retainer 30 has internal thread 50 around the interior of retainer 30. In the illustrated embodiment, internal thread 50 is an Acme thread form having a twenty-nine degree thread angle, wherein the thread height is approximately half the height of the pitch and the apex and the valley are flat. Because internal thread 50 is internal to retainer 30, internal thread 50 interfaces with external thread 37 (shown in FIG. 1) when front head assembly is attached to dispensing gun 10. In addition, retainer 30 has gripping texture 48 around the exterior of retainer 30. In the illustrated embodiment, retainer 30 has knurling as gripping texture 48. Gripping texture 48 allows for the user to get a sufficient hold around retainer 30 in order to rotate retainer 30 when attaching or detaching front head assembly 12 to or from dispensing gun 10 (shown in FIG. 1).

Also at the rear of front head body 38 arc catalyst port 40, resin port 42, solvent port 44, and air port 46. Catalyst port 40, resin port 42. solvent port 44. and air port 46 all extend into the rear of front head body 38. When front head assembly 12 is attached to dispensing gun 10 (shown in FIG. I), catalyst port 40 is tluidly connected to catalyst outlet 22. resin port 42 is fluidly connected to resin outlet 24. solvent port 44 is tluidly connected to solvent outlet 26, and air port 46 is (luidly connected to air outlet 28. Thereby, catalyst port 40 receives catalyst from dispensing gun 10, resin port 42 receives resin from dispensing gun 10, solvent port 44 receives solvent from dispensing gun 10, and air port 46 receives air from dispensing gun 10.

The components and configuration of front head assembly 12 as shown in FIG.2 allow for front head assembly 12 to be attached to dispensing gun 10 (shown in FIG. 1). More specifically, gripping texture 48 and internal thread 50 allow the user to quickly attach or detach front head assembly 12 without requiring the use of a tool. In addition, the plurality of ports 40-46 allows front head assembly 12 to receive catalyst, resin, solvent, and air.

Depicted in FIG.2 is one embodiment of the present invention, to which there are alternative embodiments. For example, gripping texture 48 can be raised portions (as are present on cap ring 35, shown in FIG. 1), knurling, stippling, checkering, or some other grip-enhancing shape and/or finish. For another example, internal thread 50 can be a square thread.

In FIG.3, a cross-section perspective view of front head assembly 12 is shown, including integrator pin 70 and check valve 80. Shown in FIG. 3 are front head assembly 12, retainer 30. tip 32. air cap 34. cap ring 35. front head body 38, catalyst port 40, resin port 42, head cavity 52, mixer housing 54, mixing cavity 56, mixing tunnel 58. mixing basin 60, static mixer 62, mixer elements 64. catalyst tunnel 66, resin tunnel 68, integrator pin 70, cylindrical base 72. wall 74, check valve 80, valve seat 82, valve poppet 84, valve spring 86, valve body 88, air vent 90, and solvent tunnel 92.

In general, front head body 38 comprises a solid cylinder into or onto which various features are formed. For example, there is shoulder 38S near the rear end of front head body 38. Retainer 30 is a ring with its own shoulder 30S a rear end of retainer 30 that corresponds with shoulder 38S on front head body 38. More specifically, a bore size in retainer 30 is larger than a width of front head body 38, except that the bore is not larger than shoulder 38S on front head body 38. This provides bearing surface upon which retainer 30 can act to secure front head body 38 when front head assembly 12 is attached to dispensing gun 10 (shown in FIG. 1). Furthermore, when cap ring 35 is installed onto a threaded portion near a front end of front head body 38, retainer 30 is captured on front head body 38.

For further examples, catalyst port 40 and resin port 42 are blind holes that are cut out of the rear of front head body 38. Mixing cavity 56 is formed in front head body 38. starling at the front of front head body 38 and extending almost, but not all the way, to catalyst port 40 and resin port 42. Catalyst port 40 and resin port 42 are fluidly connected to mixing cavity 56 by catalyst tunnel 66 and resin tunnel 68, respectively. Tunnels 66 and 68 are angled forward and toward the center of front head body 38. Specifically, tunnels 66 and 68 terminate at a portion of mixing cavity 56 that is mixing basin 60. Mixing basin 60 is a shallow, disk shaped cavity from the center of which the remaining portion of mixing cavity 56 (known as mixing tunnel 58) extends forward. Positioned in front head body 38, on the opposite side of mixing basin 60 from mixing tunnel 58, is integrator pin 70. As will be described later in greater detail, integrator pin 70 is configured such that it impedes the flow of resin from resin tunnel 68 into mixing tunnel 58, but impedes the flow of catalyst from catalyst tunnel 66 into mixing tunnel 58 to a lesser degree, if at all.

More specifically, in the illustrated embodiment, extending rearward from the front end of front head body 38 is head cavity 52. Positioned in head cavity 52 is mixer housing 54. Extending through mixer housing 54 is mixing cavity 56. Mixing cavity 56 includes mixing tunnel 58, which is a front portion of mixing cavity 56, and mixing basin 60. which is a rear portion of mixing cavity 56. Positioned in mixing tunnel 58 is static mixer 62. In the illustrated embodiment, static mixer 62 is comprised of a plurality of mixer elements 64. Each mixer element 64 has a shape of a thin rectangle that has been twisted ninety degrees along its longitudinal axis. Each mixer element 64 is oriented ninety degrees from the adjacent mixer elements 64. This means that a leading edge of each mixer element 64 is substantially perpendicular to a trailing edge of the preceding mixing element 64 (if there is one), and the trailing edge of each mixer element 64 is substantially perpendicular to a leading of the subsequent mixing element 64 (if there is one).

As stated previously, catalyst port 40 and resin port 42 extend into the rear end of front head body 38. Catalyst tunnel 66 extends forward from catalyst port 40, to a rear end of head cavity 52, fluidly connecting catalyst port 40 with mixing basin 60. Resin tunnel 68 extends forward from resin port 42, to the rear end of head cavity 52. fluidly connecting resin port 42 with mixing basin 60.

Attached lo front head body 38 at the rear end of mixing cavity 56 (which is also the rear end of head cavity 52) is integrator pin 70. In the illustrated embodiment. integrator pin 70 comprises cylindrical base 72, which is set into front head body 38. and wall 74. which extends through mixing basin 60 and into mixing tunnel 58. Integrator pin 70 is positioned between catalyst tunnel 66 and resin tunnel 68, such that catalyst tunnel 66 is directed towards inner side 76 (shown in FIG.4) of wall 74 and resin tunnel 68 is directed towards outer side 78 (shown in FIG.4) of wall 74. In addition, wall 74 is positioned between resin tunnel 68 and mixing tunnel 58.

Attached to the front end of front head body 38 is air cap 34. Air cap 34 retains tip 32. check valve 80, and mixer housing 54 in front head assembly 12. Air cap 34 has air vent 90, which is a hole that is directed toward an area in front of tip 32 where the mixture is sprayed out of front head assembly 12.. Air vent 90 is fluidly connected to air port 46 (shown in FIG.2) by an air tunnel (not shown), which is fluidly connected to the space within head cavity 52 but outside of mixer housing 54. Mixer housing 54 is relieved at various locations in the front of mixer housing 54 to allow the passage of air from head cavity 52 to air cap 34.

At the front end of mixing cavity 56 (and head cavity 52) and at the rear end of tip 32 is check valve 80. More specifically, check valve 80 is positioned within a widened end of mixer housing 54 in front of static mixer 62. Check valve 80 includes valve seat <S2, valve poppet 84. valve spring 86. and valve body 88. Normally, valve spring 86 exerts acts on valve body 88 and valve poppet 84, forcing valve poppet 84 against valve seat 82.

Also shown in FIG. 3 is solvent tunnel 92. Solvent tunnel 92 fluidly connects solvent port 44 (shown in FIG.2) with resin tunnel 68.

When the user pulls trigger 18 (shown in FIG. 1), catalyst and resin flow forward through catalyst port 40, catalyst tunnel 66, resin port 42, resin tunnel 68, respectively, into mixing basin 60. Because wall 74 is substantially blocking the resin from entering mixing tunnel 58, the resin must travel around outer side 78 (shown in FIG.4) of wall 74 to reach the opposite side of mixing basin 60 from where resin tunnel 68 intersects mixing basin 60. In the illustrated embodiment, the resin and the catalyst are pressurized up to approximately 13.8 MPa (2000 psi), although the normal working pressure is approximately 6.89 MPa (1000 psi). When the resin is diverted around integrator pin 70, its How is substantially turbulent. Because catalyst tunnel 66 is directed towards mixing tunnel 58. the catalyst has a much more direct pathway to mixing tunnel 58. But as the turbulent How of resin makes its way around mixing basin 60 on its way to mixmg tunnel 58. it partially mixes with the catalyst forming a mixture. Moreover, the turbulent How ol resin around mixing basin 60 combined with the orientation of catalyst tunnel 66 results in the catalyst entering mixing tunnel 58 encased or surrounded by resin. In the illustrated embodiment, the mixture comprises 1% to 3% catalyst and 99% to 97% resin by volume, respectively.

Having the catalyst surrounded by resin means that the catalyst is substantially near the center of the mixture when the mixture initially enters mixing tunnel 58. The column of mixture is split in two and folded over by the first mixing element 64. When the mixture reaches the second mixing element 64, the mixture is split perpendicularly to the initial split and is folded again. The process of splitting and folding is repeated at each mixing element 64 until the mixture reaches the end of static mixer 62. In the illustrated embodiment, there are eight mixing elements 64 in static mixer 62. After the mixture has flowed past static mixer 62, the mixture is sufficiently homogeneous.

After static mixer 62, the mixture enters check valve 80. The mixture exerts force against valve poppet 84, forcing valve poppet 84 off of valve seat 82. Valve poppet 84 is relieved at various locations around its outside edge, allowing the mixture to flow around valve poppet 84 and through valve body 88. After check valve 80, the mixture enters tip 32. Tip 32 shapes the How of the mixture as it exits front head assembly 12. In addition, air from air vent 90 shapes the How of the mixture after it has left front head assembly 12.

When the user releases trigger 18 (shown in FIG. 1). How of catalyst and resin into front head assembly ceases. Catalyst and resin retain some residual pressure, which urges the mixture in front head assembly 12 out of tip 32. But valve spring 86 is of sufficient strength to close check valve 80 against this residual pressure. This prevents the mixture in mixing cavity 56 from leaking out of tip 32 after trigger 18 has been released. Thereby, the only mixture allowed to exit front head assembly 12 after trigger 18 (shown in FIG. 1) is released is the small amount contained in valve body 88 and tip 32.

If dispensing gun 10 (shown in FIG. 1) will not be used before the gel time of the mixture (in the illustrated embodiment, ten minutes), the user is advised to flush front head assembly 12 with solvent. Solvent enters solvent port 44 (shown in FIG. 2) and travels through solvent tunnel 92, into resin tunnel 68. The solvent Hows forward, displacing any resin, catalyst, or mixture in its path. After sufficient flushing, none of the mixture remains in front head assembly 12. This is important because otherwise the mixture would harden and foul front head assembly 12 if left undisturbed (bra sufficient amount of time. In addition to or in place of the flushing process, front head assembly 12 can be removed by the user and placed in a solvent bath for cleaning and/or storage. If front head assembly 12 is removed, another one can be attached in its place while the original one is being cleaned and/or stored.

The components and configuration of front head assembly 12 as shown in FIG.3 allow for the resin and the catalyst to be mixed and dispensed out of front head assembly 12. More specifically, the catalyst is encased or surrounded by the resin and pre-mixed prior to being sufficiently homogenized by static mixer 62. Having the catalyst initially substantially centered in the mixture substantially prevents the catalyst from flowing alongside the resin (and not truly mixing) as they flow by static mixer 62. In addition. when the user desires to cease dispensing of the mixture, check valve 80 prevents the residual pressure in the mixture from propelling most of the mixture left in front head assembly 12 out through tip 32.

Depicted in FIG.3 is one embodiment of the present invention, to which there are alternative embodiments. For example, solvent tunnel 92 can be connected to resin port 42. For another example, there can be more or less mixing elements 64 than eight. For a further example, wall 74 can extend across mixing basin 60 substantially to mixing tunnel 58. In such an embodiment, integrator pin 70 does not extend into mixing tunnel 58.

In FIG. 4. a side perspective view of integrator pin 70 is shown, including cylindrical base 72 and wall 74. Shown in FIG.4 are integrator pin 70, cylindrical base 72, wall 74, inner side 76, outer side 78, cylindrical face 94, circular face 96, diameter 98, and cut 100.

As stated previously, integrator pin 70 comprises cylindrical base 72 and wall 74. Cylindrical base 72 has cylindrical face 94 around the circumference of cylindrical base 72 and circular face 96 at an end of cylindrical base 72. Circular face 96 has diameter 98 extending across circular face 96. On an end of cylindrical base 72 that is opposite of circular face 96, cylindrical base 72 has a chamfer that eliminates what would otherwise be a sharp edge.

In the illustrated embodiment, wall 74 extends from circular face 96. Wall 74 includes outer side 78 that extends from circular face 96 substantially along cylindrical face 94. Wall 74 also includes inner side 76. w hich extends from circular face 96 and is substantially uniformly offset from outer side 78. In the illustrated embodiment, integrator pin 70 is generally formed by cutting a hole into the center of a solid cylinder. and wall 74 is formed by cutting across the side of the cylinder, breaking through into the hole. More specifically, wall edge 100 is the line along which the cutting is done. This means that wall 74 is substantially a circular arc that subtends more than a hemisphere (one hundred eighty degrees) having a substantially uniform radial thickness. Wall 74 subtends approximately 60% of a circle (two hundred sixteen degrees) because wall edge 100 is offset from diameter 98. In addition, wall 74 extends substantially across an entire length of diameter 98, although wall 74 is not positioned along diameter 98. An outer end of wall 74 is chamfered towards outer side 78, which eliminates what would otherwise be a sharp edge.

The configuration of integrator pin 70 as shown in FIG.4 allows for interruption of the flow of resin from resin tunnel 68 (shown in FIG.3) to mixing basin 60 (shown in FIG. 3). In addition, the How of resin around integrator pin 70 is turbulent. Furthermore, integrator pin 70 allows for the catalyst to be interjected towards the center of the resin flow, which helps ensure that the mixture is sufficiently homogeneous prior to being dispensed. In addition, the chamfered ends of integrator pin 70 allow for easier manufacturing and assembly of front head assembly 12 (shown in FIG. 1) as the chamfers eliminate potential burred edges.

Depicted in FIG.4 is one embodiment of the present invention, to which there are alternative embodiments. For example, wall 74 can subtend more than 60°/<> of a circle. For another example, wall 74 can subtend less than 60% of a circle. In such an embodiment, diameter 98 and wall edge 100 can be colinear. For a further example, there can be two non-colinear wall edges 100. In such an embodiment, wall edges 100 can be parallel and perpendicular to diameter 98. For yet another example, wall 74 can extend substantially across an entire length of diameter 98 by being positioned across diameter 98. It should be recognized that the present invention provides numerous benefits and advantages. For example, there can be fewer mixer elements 64 in static mixer 62 because the resin and the catalyst are pre-mixed, and the catalyst is initially substantially near the center of the mixture. For another example, front head assembly 12 can be removed from dispensing gun 10 quickly, easily, and without tools. For a further example, front head assembly 12 does not leak a substantial amount of the mixture after the user has released the trigger.

While the invention has been described with reference to an exemplary cmbodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

CLAIMS:

1. A front head assembly for a plural component dispensing gun, the front head assembly comprising:

a front head body having a plurality of ports at a rear end of the front head body and a head cavity extending into a front end of the front head body;

a static mixer positioned in the front head cavity between the plurality of ports and the front end of the front head body; and

an integrator pin positioned in the interior of the front head body between the plurality of ports and the static mixer.

2. The front head assembly of claim I. and further comprising:

a check valve positioned at the front end of the front head body, in front of the static mixer.

3. The front head assembly of claim 2, and further comprising:

an air cap attached to the front end of the front head body; and a tip positioned between the air cap and the check valve.

4. The front head assembly of claim 1 , and further comprising:

a retainer connected to the front head at the rear end of the front head body for securing the front head body to the dispensing gun.

5. The front head assembly of claim 4, wherein the retainer is threaded with an Acme thread form.

6. The front head assembly of claim 4, wherein the retainer is a threaded retaining ring having a gripping texture.

7. The front head assembly of claim I, wherein the plurality of ports com prises:

a catalyst port for receiving catalyst from a dispensing gun body;

a resin port for receiving resin from the dispensing gun body; a solvent port for receiving solvent from the dispensing gun body; and an air port for receiving air from the dispensing gun body.

8. A front head for a plural component dispensing gun, the front head comprising:

a front head body having a rear end and a front end;

a mixing cavity extending into the front end of the front head body, the mixing cavity having a mixing basin at a rear end of the mixing cavity and a mixing tunnel extending to the front end of the front head body from the mixing basin;

a resin port extending into the rear end of the front head body;

a catalyst port extending into the rear end of the front head body;

a resin tunnel lluidly connecting the resin port to the mixing cavity;

a catalyst tunnel fluidly connecting the resin port to the mixing cavity; and

an integrator pin attached to the front head body at the rear end of the mixing cavity, the integrator pin having a wall that extends into the mixing basin, wherein the integrator pin is positioned betw een the catalyst tunnel and the mixing tunnel.

9. The front head assembly of claim 8. w herein the integrator pin extends through the mixing basin to the mixing tunnel.

10. The front head assembly of claim 8, w herein the integrator pin comprises:

a cylindrical base having a circular face and a cylindrical face;

a wall extending from the circular face, a projection of the wall extending substantially across an entire diameter of the circular face, wherein the wall extends through the mixing basin to the mixing tunnel.

11. The front head assembly of claim 10. w herein the catalyst tunnel is oriented toward an inner side of the wall and the resin tunnel is oriented toward an outer side of the wall.

12. The front head assembly of claim 8, and further comprising:

13. The front head assembly of claim 12. w herein the retainer is threaded with an Acme thread form.

14. The front head assembly of claim 12. w herein the retainer is a threaded retaining ring having a gripping texture.

I 5. The front head assembly of claim 8. and further comprising:

a check valve attached to the front head body at a front end of the mixing cavity.

16. The front head of claim 8, and further comprising:

a solvent port extending into the rear end of the front head body; and a solvent runnel fluidly connecting the solvent port with the resin tunnel.

17. An integrator pin for a plural component dispensing gun, the integrator pin comprising:

a cylindrical base having a circular face and a cylindrical face;

a wall extending from the circular face, the wall extending substantially across an entire diameter of the circular face.

I8. The integrator of claim 17, wherein the wall is substantially a circular arc.

19. The integrator of claim 18, wherein the wall includes an outer side and an inner side, the outer side extending from the circular lace substantially along the cylindrical face, and the inner side extending from the circular face substantially uniformly offset from the outer side.

20. The integrator of claim IS, wherein the wall subtends at least a hemisphere.